EPA Center on Airborne Organics
1997 Summer Symposium Report
 
 
"Fine Particles in the Atmosphere"
Table of Contents
 
 
Session I - Moderator: Glen Cass  Opening Remarks and EPA Criteria Document   
Opening remarks, Glen Cass, California Institute of Technology 

The PM Criteria Document, Lester Grant, Environmental Protection Agency (EPA) 
 

Atmospheric Characterization   
Measurement Methods, Susanne Hering, Aerosol Dynamics, Inc. 

Ambient Concentrations, Richard Scheffe, US EPA 
 

Health Effects   
Epidemiological Findings, Frank Speizer, Harvard Medical Schoo
 
Emission Sources   
Sources of Airborne Particles, Lynn Hildemann, Stanford University
Session II - Moderator: Praveen Amar  Connecting Emission Sources to Atmospheric Concentrations   
Modeling Atmospheric Transport and Transformation, Pradeep Saxena, Electric Power Research Institute (EPRI) 

Source Attribution, Glen Cass, California Institute of Technology 

Mobile Sources, Pat Flynn, Cummins Engine Co. 

Stationary Sources, Michael Wax, Institute of Clean Air Companies 

Control of Atmospheric Particulate Matter- A Congressional Perspective, William Tyndall, US House of Representatives Committee on Energy and Commerce 
 

Regulation and Control   
Fine Particle Concentration and Chemical Composition in the Northeast, Glen Cass, California Institute of Technology 

Alternative Control Strategies and Methods for Monitoring Progress -or- A View on Implementation of EPA's Fine Particle Standard, Robert Slott, Consultant 
 

Panel Discussion: Issues Confronting States in Meeting Standards   
John Bachmann, US EPA (via speaker phone) 

John Elston, New Jersey Dept. of Environmental Protection 

Jim Price, Texas Natural Resources Conservation Commission 

Jason Grumet, NESCAUM 

Richard Scheffe, US EPA

Session III - Frontiers of Health Effects Research, Moderator: Jane Warren  What new data are likely to become available to inform future decisions?   
Studies Using Concentrated Ambient Particles, John Godleski, Harvard School of Public Health 

Cytokines and Oxidative Stress as Factors in the Lung's Response to Particles, Kevin Driscoll, Procter and Gamble 

Role of Metals in the Biological Effects Associated with Air Particulate Matter Exposure, Kevin Dreher, U.S. Environmental Protection Agency

Session IV - Moderator: Jane Warren  Panel Discussion: Effectiveness of Standards in Addressing Health Issues   
Joe Mauderly, Lovelace Respiratory Research Institute 

Frank Speizer, Harvard Medical School 

Ron White, America Lung Association 

Fred Miller, Chemical Industry Institute of Toxicology 
 

Closing Remarks, Glen Cass, California Institute of Technology



SESSION 1

Moderator: Glen Cass

Opening Remarks and EPA Criteria Document

Opening remarks

Glen Cass, California Institute of Technology

Professor Cass introduced his co-chairs Praveen Amar and Jane Warren and encouraged open discussion throughout the symposium. He listed and thanked the sponsoring companies. He summarized the expected PM 2.5 standards, which will be announced on July 19th. The standards are as follows: a 24 hour average limit of 65 mg/m3 and an annual average limit of 15 mg/m3. He showed pictures of the air around the campus of California Institute of Technology in order to contrast the air quality on days with low and high particle concentrations. The particles on the high concentration day were almost entirely fine. Visibility was markedly reduced on the high particle concentration day.


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The PM Criteria Document

Lester Grant, Environmental Protection Agency (EPA)

Dr. Grant summarized the duties of the EPA as laid out in the Clean Air Act, specifically how the EPA goes about defining the National Ambient Air Quality Standards (NAAQS) for the criteria pollutants. He said that primary standards are defined in order to protect public health, while secondary standards are defined to protect public welfare. Standards are set with the health and environmental effects, not costs, in mind, while in achieving the standards one deals with costs and time requirements. Every 5 years, the EPA must perform a review of the standards. The review and assessment of the NAAQS consists of a review of scientific studies and leads to the EPA criteria documents.

The review process for the standards is as follows: Scientific studies on health and environmental effects of the pollutants as well as a peer review of these studies are used to create the criteria document, which is reviewed by CASAC and the public. The EPA then creates the staff paper, which interprets the scientific data and proposes new standards. This paper is also reviewed by CASAC and the public. The EPA decides on a proposal for the standards, and after public hearings and comments, makes a final decision.

Grant listed the dates for these events, the upcoming event being the notice of final action on July 19, 1997. Because of a new law from Congress, the legislature has 60 working days to evaluate the changes proposed by the EPA.

Q: NESCAUM Representative Congress has not yet acted under that statute. Can Congress wholly overturn the EPA standard with this new "unprecedented" law?

A: Yes, it is within their power to do so.

Grant summarized the scientific basis of new PM standards. Eighty key studies, which found a link between PM10 and premature death or serious illness, were used. Differences between fine and coarse PM as found in epidemiological studies and differences in composition and exposure are as follows:

Fine PM

Coarse PM After showing a size distribution for usual airborne PM, he posed the questions: Should the standard be PM2.5 or PM10 since 1.0 mm is the measured separation between fine and coarse modes? Should there be an ultrafine PM standard because of the large number and high surface area per unit mass of these particles, as compared to PM2.5?

He listed the manifestations of PM adverse health effects as premature deaths, illnesses, decreased lung function, increased work loss days and school absences, and changes in lung structure and natural defense systems. He went on to comment that the health effects of PM are independent of co-pollutants. There is a consistency across studies. When separating effects of PM2.5 and PM10, the concentration of PM2.5 is proportional to relative risk. Some members of the audience questioned the validity of that conclusion due to one outlying datum, the Topeka point. Studies have found that there is no threshold for health effects.

Because of questions about the statistical validation of these data points regarding relative risk for the Harvard Six-City study, Grant tried to back up the choice of 15 mg/m3 standard with data of the 95% confidence intervals for RR. The audience commented that the points at the 10 and 30 mg/ m3 seemed to show the same effect, but he showed epidemiological data in order to suggest the contrary. He added that coarse particles are still a concern.


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Atmospheric Characterization

Measurement Methods

Susanne Hering, Aerosol Dynamics, Inc.

Dr. Hering summarized atmospheric concentrations of PM: 1,000 to 100,000 per cm3, or 2-200 mg/m3. She showed how the particles can assume a wide range of shapes and compositions. She suggested that because the morphologies or shapes, chemical composition, and phases vary so much, it is difficult to lump all particles under one heading like PM2.5 or PM10. She further suggested that in measuring particles, one must either use some kind of average in order to simplify the data -- average over the chemical compositions, over the particle sizes, over single particle compositions in a narrow size fraction, or over size and composition -- or measure real-time concentrations of a single particle size, composition, and morphology. She showed representative size distributions for PM with various chemical compositions at different times. She showed the effect of PM transport using size distributions, particularly the number distribution. The effect of transport is less obvious in the mass distribution, and number distribution picks up ultrafines, which come from combustion sources.

Q: Is the data reproducible?

A: Yes, if you are near fresh combustion sources.

Q: Why did you choose to present this particular set of data?

A: It showed a contrast.

After showing a comparison of several samplers with different cleaning schedules, she suggested that there is a need to enhance PM monitoring and a need for a defined code concerning the sampler cleaning. She described the measurement method as a filter preceded by a denuder (for gas removal), and noted that because there is less nitrate evaporation in this system it picks up more PM mass than a regular Teflon filter-based sampler. Comparison of the results of different sampling techniques showed that, while the systems were sometimes comparable, one technique had losses, possibly as high as 80% for some species. Q: Do the losses occur on the filter?

A: Yes, and at the inlet.

Dr. Hering summarized the current status of pollutant monitoring, including PM10 mass, ozone, CO, and NOx. She pointed out that the PM measurements are more limited and incomplete compared to the gaseous pollutants. In particular, the gases are measured continuously, while PM10 is measured with very limited time resolution. Q: Many of the size distributions shown have bimodal distributions with peaks at 0.2 and 0.8 mm, so are we masking the two modes by lumping all of the fine particles under the one name?

A: There is not enough data to support the two modes of fine particles.

Dr. Hering suggested that perhaps automated in-situ measurements may improve accuracy, and summarized the current state of particle sampling. She showed a variety of data, both time-resolved particle concentrations and size distributions, made via a number of measurement techniques both outdoors and indoors. Differences between indoor and outdoor concentrations is probably caused by gaseous concentrations, particularly of nitrate, which suggests the need for improved measurement techniques that handle nitrate better. The comment was made that nitrates can be formed from cooking.

She noted that the regulated parameter is what comes out on the filter, which is not necessarily the same as what is in the air, leading to possible biases.

Questions and Discussion:

Q: Bob Slott, Consultant Should we not worry about biases but rather concentrate on maintaining consistency?

A: Standards should be tied to the measurement technique, but effort should be placed upon finding the best measurement methods.

C: Glen Cass We can improve measurements, we have the scientific basis to do so, but these techniques take more money. We understand how the measurement techniques generate artifacts.


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Ambient Concentrations

Richard Scheffe, US EPA

Dr. Scheffe commented that population and VMT have gone up and total emissions have gone down, but he suggested that air quality may not be getting better. He noted that settling and transport make PM2.5 a problem on a regional scale. He showed the sites taking ambient concentration data across the country and pointed out that the data suggest that annual PM10 values have been going down for several years. He discussed seasonal changes in PM2.5 (measured via visibility) and explained the seasonal trends in terms of photochemistry.

He highlighted the differences in seasonal behavior of PM2.5 between eastern and western locations, pointing out that PM2.5 is largely sulfur-based in the East, but not in the West. Organic aerosols, however, behave similarly across the country. Nitrates are present in the East, especially during winter. Trends from season to season are explained in terms of chemistry, particularly SO2 to sulfate and NOx to nitrate conversion.

Q: This data mimics NAPAC data of the 80?s; why hasn?t it been shown?

A: I am just showing the recent data.

Dr. Scheffe commented that spatial averaging and chemical speciation are needed in the monitoring part of the PM2.5 proposal. The federal reference method measures only a tracer, as Susanne Hering said. EPA staff would like the most emphasis on mass measurements, with some emphasis on species measurement and less on size distribution.

He noted that with three year averaging on NAAQS, attainment data will not be available until calendar year 2002. Further, the annual standard will be the controlling standard, especially in the East. Finally, he noted that often there is co-episodic behavior between PM2.5 and ozone.

Questions and Discussion:

Q: Why decrease DMCO?

A: Lack of resources force us to allocate funds according to preferences.

C: Ask for more resources.

Q: How will the EPA select sites for health studies?

A: They will be placed in community areas, plus some background sites.

Q: How will you collect data on particle number concentration, which must be collected?

A: Not only number concentration, but speciation must be measured. We need to head in that direction.

Q: Will you do accurate chemistry?

A: We will use Teflon filters, Nylon filters, and Quartz filters.

C: So you will try to do it correctly?

A: "Correctly" is a moving target.


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Health Effects

Epidemiological Findings

Frank Speizer, Harvard Medical School

As an introduction to his talk, Dr. Speizer presented some historical examples of the epidemiology of particle pollution: 12thcentury observations regarding smoke and 1948 Donora, PA, and 1952 London episodes of high PM and related morbidity rates. He presented data from recent epidemiological studies. The effects of PM are increased mortality, increased morbidity, increased school absences and work loss, decreased lung function and symptoms thereof, and lung morphological changes. Relative risk of death or morbidity among the elderly is from 1.01 to 1.05 in many studies, per 50 mg/m 3increase in 24 hour PM10 levels.

Q: Why do you use the ?per 50 mg/m3 increase??

A: For similarity of mathematical scales between studies.

Q: Bob Slott, Consultant Was "increase" in health problems more important than the absolute particle loading? In other words, was the derivative of the load more important than the magnitude?

A: The relative risk seems to be more consistent than a change or increase in risk. Since different cities had different levels of particle loading, we just looked at the effect of a 50 mg/m3 increase.

Q: You assumed a linear relationship with no threshold?

A: Correct.

Dr. Speizer presented data correlating the relative risk of airborne particulate matter to that of smoking, in terms of the risk of all causes of death, death via lung cancer, and death via cardiopulmonary disease. After taking into account the effects of smoking, particulate effects were still present.

Dr. Speizer made a comparison of data from an American Cancer Society study and the Harvard Six-City Study on the relative risk of PM on smokers and non-smokers and showed that the results were consistent between the two studies. He presented data from a study on post-neonatal infant mortality versus air pollution. The study showed that some infant deaths are associated with high PM10 concentrations. That is, the relative risk for these infants was generally greater than one.

In summary, Dr. Speizer noted that in spite of environmental issues and co-pollutants, the PM effect seems consistent and that mechanistic information related to epidemiology is needed.

Questions and Discussion:

Q: The data do not show a threshold, does this cause you some anxiety?

A: We started out thinking that there would be a threshold, but now we do not suspect one.

Q: Since the data do not show a threshold, where do we draw the limit on the risk that we are willing to tolerate and the controls that we are willing to pay for?

A: It would have to be a policy decision (rather than a political one), and it must be made in the context that we are likely to leave some portion of the population at risk. The law at present is not written in this form but from a practical perspective this is what has to be done. As example of a primary criteria pollutant in which this was done is carbon monoxide where the standard that was set leave a small portion of the population at risk, those with sickle cell anemia.


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Emission Sources

Sources of Airborne Particles

Lynn Hildemann, Stanford University

Professor Hildemann characterized the sources of particles: anthropogenic (stationary, mobile, fugitive) versus biogenic particles, and primary versus secondary particles. Anthropogenically-emitted precursors are SO2, NOx, VOCs, and NH3. Naturally-emitted precursors are H2S, NOx, and VOCs. She summarized the mechanisms for generating primary particulate emissions: mechanical generation, volatilization, and combustion. Because mechanically generated PM mainly exists in particle diameters greater than 2 um, it tends to be a less significant contributor to fine PM. Low volatility gases released during heating processes tend to condense on fine particles due to the high amount of surface area. Combustion sources generate mainly submicron particles, which can contain a variety of chemical components. She drew the conclusion that volatilized and combustion-generated particles will become more important as PM sources under the new fine PM regulations. In a comparison of the fractional breakdown of the chemical compositions of fine PM from various sources, she showed that fine elemental carbon (EC, or soot) is a significant component in combustion generated PM, while volatilized PM tends to consist primarily of organic carbon (OC). For some sources of mechanically generated PM (like road dust and vegetative detritus), re-entrainment of dry deposited PM must be considered.

Professor Hildemann summarized her dilution sampling method and compared it to the EPA Method 5, showing schematics of both methods. She described the strengths and weaknesses of each and presented data generated by using each method to sample from an industrial boiler. Because the particle volume increases as the exhaust cools, the temperature at which the samples are taken is important. An advantage of the dilution method is that it measures as PM those organics which will condense under ambient conditions; the EPA method does not.

Questions and Discussion:

Q: Regarding scales and how the identification process is done: why is the identification rate approximately 80% for all sources?

A: This is just due to the technique's identification capabilities. Some of the uncharacterized material may be water, for example.

Q: What artifacts are introduced by the dilution sampler's Reynolds Number of 10,000?

A: This causes a faster dilution than what occurs in the atmosphere, so there may be a change in the rates of chemical reactions, but losses of particles to the sampler walls are minimal.

Q: So you have an underestimation?

A: No, the chemical reactions may change, but not the fine particle mass or the equilibration of semi-volatiles.

Q: Does repeatability depend on dilution ratio?

A: Not as much as on other factors like the excess-air ratio.

Q: Does dilution ratio affect size distribution?

A: Coagulation is inhibited by the higher dilution ratio, but overall results are presumably not affected because particle sizes will remain in the fine fraction of interest, regardless.

Q: Did you look at the condensibles collected by Method 5?

A: No, but others have.

C: Characterization of secondary sources is difficult for reasons similar to those posed by Susanne Hering. There is a need for more data that can be used in modeling.

Q: In the East, natural VOC emissions can be significant. The lack of speciation data on VOCs and effect on PM beg the question, are VOCs important in the formation of PM?

A: Not that I am aware of.

C: Glen Cass, California Institute of Technology Natural VOCs are not as important in forming PM in urban areas, but they can be a relatively higher fraction in rural areas, for example the Grand Canyon, particularly because they make up a larger percentage of emissions.

Q: Explain the variations in boiler data with respect to dilution ratio.

A: Stoichiometry changed and affected the boiler output, especially with respect to EC emissions. Fuel batch and the boiler operator were other potential sources of variation in these field experiments.
 
 


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SESSION 2

Moderator: Praveen Amar

Connecting Emission Sources to Atmospheric Concentrations

Modeling Atmospheric Transport and Transformation

Pradeep Saxena, Electric Power Research Institute (EPRI)

The speaker presented data from California (CA) and the Smoky Mountains National Park (SMNP) for PM2.5. Sulfate and organics measurements were consistent from sampler to sampler. For the CA data, 18% is unidentified mass, 38% for the SMNP data. The explanation given was that the unidentified mass was likely water and/or inaccuracies in other measurements in the CA data and 11-25% water with the remaining mass being perhaps higher molecular weight compounds for the SMNP data. Dr. Saxena stressed that this unknown fraction presents a challenge to modeling efforts. Dr. Saxena then presented results for several models. The agreement of model predictions to the data was within an order of magnitude. He made the following points about the modeling studies:

1. A reductionist approach to modeling may lead to inaccuracies, and the best approach is to hold off on simplifying assumptions until necessary.

2. More data is needed to test the models.

3. The error is still large in the model predictions, but significant progress has been made.

Questions and Discussion: Q: Sulfate oxidation was once thought to be a homogeneous reaction, but is now thought to be a heterogeneous reaction. Could the same be true for organics?

A: Yes, oxidation of VOCs in aqueous phase is quite possible and to my knowledge hasn't been investigated.

Q: How good are the models for predicting annual averages?

A: Most of the models are on an hour-to-hour basis. You can make a synthetic year out of, say, 28 episodes. A synthetic year approach is a potentially attractive alternative to exercising a reduced-form model for the whole year.


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Source Attribution

Glen Cass, California Institute of Technology

Professor Cass began with asking the central question of how, after the standards have been set, does one distribute controls among various sources? The topic of this presentation was the methods available to determine source attribution. There are two basic approaches:

1. Transport and reaction models

2. Chemical tracer studies

In regard to transport and reaction models, a major consideration is characterization of emissions. The effectiveness of atmospheric modeling is dependent on the data input to the models. A complication in this task is that the largest difference in PM10 and PM2.5 levels arises from fugitive emissions. Cass presented results of modeling of the growth of particles from various sources, giving detailed chemical composition of the particles and particle size. He pointed out that the composition of particles is of central importance and that one can resolve the mass to with in 2% using gas chromatography/mass spectrometry. Analytical results suggest that there are significantly more PAH and more oxygen-containing compounds in emissions from non-catalyzed autos than from catalyzed autos.

Questions and Discussion:

Q: Why did you choose the foggy day to model?

A: It was a consequence of the available data. We did include the fog interaction in the model.

Q: How do you attribute sources?

A: The data is over-determined, so the results are "dead-on".

Q: PM2.5 standards could be met if fuel from power plants was desulfurized, so why does your data not show this?

A: This is true only for the East, not in LA, since this has already been done.

Q: Frank Speizer, Harvard Medical School How far away are we from having a pager-sized sampler to get particle data?

A: The problem is not collecting the sample, but the time required to collect enough sample (~300 micrograms) and the analysis of the sample.

Q: Has anything been done to limit char-broilers and meat cooking?

A: Work has been done on catalytic converters for commercial broilers.

Q: Will you discuss biogenic activity of PM?

A: That's another talk.

Q: How does the model treat the secondary organic formation?

A: It uses the Pandis et al. model for secondary formation and condensation.

Q: How do you get size distributions? What are the available techniques?

A: Most of the data shown are model predictions of size distributions, but the techniques are electrostatic aerosol analyzer, differential mobility particle sizer, and light scattering.


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Mobile Sources

Pat Flynn, Cummins Engine Co.

Dr. Flynn noted that the diesel engine industry has responded and reduced emissions to comply with tightening particulate standards. He pointed out that the epidemiology of very fine particles (ultra-fine or smaller) is unknown. The health effects of these very fine particles is crucial information, since small particles emissions appear to be increasing even as the total emissions levels from diesel engines are decreasing. The number of very small sulfate particles has been reduced as the sulfur content of fuels has been reduced nationwide. As seen in experimental data, increasing the sulfur content of fuel increases the number of ultra-fine particles that are formed. Modeling efforts suggest that there is a trade-off between NOx production and particle formation. Higher combustion temperatures provide burnout of fine soot particles but also promote NOx production. The modeling also suggests that lower combustion times limit agglomeration of soot particles, leading to emission of more particles with smaller diameters.

Questions and Discussion:

Q: Tony Dean, Exxon I am not as confident in the soot modeling, especially after talking to the modelers from Lawrence Livermore National Laboratory.

A: We are confident about this.

Q: Lester Grant, US EPA What happens in the tailpipe?

A: These data are from the tailpipe plus dilution tunnel.

Q: Steve Japar, Ford How does the coagulation process behave during the exhaust process?

A: This data shows that since it is after the tailpipe.

Q: Joseph Somers, US EPA Steady-state tests are easy, but the concentrations are low. Transient concentrations are higher. Do you have transient measurements?

A: We do mode-by-mode modeling as well as steady-state.

Q: Michael Redemer, Texaco Can this work be applied to smaller diesels?

A: Yes, it scales.

Q: Jack Howard, MIT I agree with Tony Dean on modeling difficulties. How can you be sure on the nature of the physical process producing the smaller particles, since the end formation of particle number is controlled by the competing processes of formation and oxidation?

A: We think the smaller particles come from shutting off the agglomeration.


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Stationary Sources

Michael Wax, Institute of Clean Air Companies

Dr. Wax opened by explaining that large stationary sources are prime targets for fine particulate emissions reductions because they are easier and less expensive to control than small stationary sources and non-traditional sources. The most common controls for primary fine particulate are electrostatic precipitators and baghouses. Well-designed precipitators have PM2.5 removal efficiencies of at least 97-98%, and a new precipitator will remove particulate from a coal-fired power plant for less than about $150 per ton. Baghouses provide 99.9% overall mass removal efficiency, and over 99% PM2.5 removal efficiency, and a new baghouse on a coal-fired power plant will cost less than $175 per ton of particulate removed. Dr. Wax pointed out that most large sources are already controlled, so future control generally will require upgrades rather than new controls systems. The incremental cost of control will be higher than the numbers noted above, but still reasonable. For secondary particulate control, fuel switching and scrubbers are cost-effective options for reducing SO2 emissions, and various post-combustion technologies are cost-effective options for deep reductions in NOx emissions. Dr. Wax noted that a byproduct of control of primary and secondary fine particulate emissions from stationary sources will be reductions in air toxics emissions, acid rain, and tropospheric ozone.
 
 

Questions and Discussion:

Q: How well do you have to clean the bags in baghouses?

A: You do not want to clean them too well because the dust cake on the bags aids filtration.

Q: Is Selective Catalytic Reduction (SCR) effective?

A: Greater than 90% NOx reductions are achievable with SCR.

Q: John Beér, MIT Is combustion process enhancement effective? For example, flue-gas recirculation.

A: Yes and no. Low NOX burners can get low emissions and adding SCR can make additional reductions.

Q: Is EPA's emission factor mistaking the relative contribution of stationary sources?

A: Yes - stationary sources contribute a larger fraction of the total than the emissions factors suggest.
 
 


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Control of Atmospheric Particulate Matter- A Congressional Perspective

William Tyndall, US House of Representatives Committee on Energy and Commerce

Mr. Tyndall began by noting that Rep. Dingle, the chairman of the U.S. House of Representatives Committee on Energy and Commerce was in opposition to the proposed PM2.5 standard. Historically, there has been consensus for passing environmental standards. However, there is no congressional consensus for the proposed standards for PM2.5 and ozone. Mr. Tyndall pointed out that CASAC offered advice to EPA Director Browner that would allow weaker, tighter, or unchanged PM regulations. Congress has several options:

1. Veto the PM standard, but since the President is in favor of the standard a two-thirds majority vote in Congress would be required.

2. Attach some limitations to the standard to an EPA appropriations bill.

3. Pass a law preventing EPA from establishing new standards and forcing them to put off the standard until some future date.

4. Pass a law on implementation without EPA standards to back them.

Mr. Tyndall made the point that both parties (EPA and Dingle-led opposition) are asking for more research and a possible tightening of standards. The PM2.5 opponents merely ask for postponement of standard setting until the further research is completed.
 
 

Questions and Discussion:

Q: Bob Slott, Consultant Could the matter be taken to courts to force implementation if the standard isn't passed?

A: It is possible, but statutory certitude is desired.

Q: Steve Japar, Ford EPA plans to announce PM and ozone standards together. What effect will one have on the other?

A: EPA wants to implement the standards simultaneously so that states can coordinate their efforts, especially since precursors are linked.

Q: Ken Colburn, NH Dept. of Environmental Services Since CAA regulates by recipients rather than sources, therefore disadvantaging the Northeast relative to other parts of the country, couldn't Dingle be acting for reasons other than health concerns?

A: A fair point, but NAAQS are not the ideal solution since the CAA has such leniency in terms of time of attainment.

Q: You can replace the scientists, but I don't think you will get more information in five years. I don't think you've thought it through completely.

A: I disagree. There was no consensus on what the standard should be. You guys are in the middle of the process.

Q: Lester Grant, US EPA Will five years change things?

A: Mechanistic ties will build a stronger consensus in Congress.

Q: Larry Gephardt, Exxon What is the likelihood of getting more funding for epidemiological studies?

A: Very likely.

Q: Rich Poirot, Vermont Dept. of Environmental Conservation If Congress takes action is it going to set a precedent where it takes over the standard setting and bases standards on the cost of implementation?

A: Unfortunately, yes.

Q: Fred Miller, CIIT Consensus is missing from the annual standards, though it is there for the 24 hour standards. Will this have the effect of allowing Congress to strike down the PM standards?

A: EPA cannot change standards in four years but must change them in the fifth.

Q: Jeff Crawford, Maine Dept. of Environmental Protection Since EPA is under court order to make a decision on PM, does possible Congressional action have to be challenged by a court if it acts against EPA?

A: EPA is only under court order to make a decision. They could be subject to further court action.

Q: Bob Slott Can environmental groups retaliate on slow action of PM and ozone standards?

A: Any solution must be fair about the implementation across the country.

Q: Bob Slott Why was Safe Drinking Water Act not followed as the model for PM and ozone standards?

A: We may be able to improve this in the future.


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Regulation and Control

Fine Particle Concentration and Chemical Composition in the Northeast

Glen Cass, California Institute of Technology

Professor Cass presented PM data from Rochester, NY; Brockport, NY; Quabbin Reservoir, MA; Woburn, MA; and Boston, MA. The samples were taken using a method similar to what will be the standard EPA method, which is not artifact free. A significant finding is that there is very little difference in rural and urban areas, and there is spatial uniformity throughout the Northeast in concentration levels. Overall, the levels are very close to the proposed standard of 15 mm/m3. The standards are only exceeded in the cities, and then only by 10-20%.

Questions and Discussion:

Q: Richard Magee, NJIT Would removing sulfates cause a shift to more nitrates?

A: Possibly. We have enough scientific knowledge to analyze this possibility.

Q: Is the sulfate being imported?

A: The sulfate was present before it hit Rochester, NY.

Q: Tony Dean, Exxon What should we cut?

A: I will not engage in the health effects debate. I will just tell people what is there.

Q: What is the effect of road dust?

A: It settles out because of its large particle size.

Q: Bob Slott, Consultant How long before the levels drop below PM2.5 without the regulations?

A: I'm not willing to speculate. However, many of the changes that drastically reduced PM cannot be repeated, such as desulfurizing fuel and adding catalytic converters to autos

Q: Michael Wax, Inst. of Clean Air Companies How does your sampler compare to FRM?

A: FRM is an impactor, ours is based on a cyclone. I expect the numbers to be similar.


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Alternative Control Strategies and Methods for Monitoring Progress -or- A View on Implementation of EPA's Fine Particle Standard

Robert Slott, Consultant

The speaker suggested that EPA should maintain existing regulatory strategies with respect to other pollutants and gather more data on PM2.5 to meet the goal of protecting public health. he suggested a plan to get the most data and resolve the most pm issues for the least cost. To accomplish this, all factions involved should participate in the planning and funding of research and monitoring to be done in the next five years. In particular, EPA should take the lead and:

  1. Bring the stakeholders together for discussion and cooperation.
  2. Encourage both joint and parallel study of the PM problem by the stakeholders.
  3. Devise "shoot-outs" to competitively compare different monitoring and control techniques.
  4. Set up legislation to keep the standards out of the courts for five years.
  5. Use the most accurate sampling methods to avoid biasing in the PM measurements.
  6. Conduct chemical speciation analyses at regional labs to ensure appropriate quality control.
  7. Encourage the administration (i.e., the President and Congress) to maintain consistency in protecting the public health by focusing on indoor, as well as outdoor, air quality issues.
Elaborating on his summary, Dr. Slott commented on the proposed PM standard, cautioning that the costs for meeting the standard are projected to be in the billions, that data show PM levels are decreasing without additional regulation, and that "good regulation" is one in which policy is based on the best, although incomplete, science that is available at the time. He further suggested that EPA's implementation plan should be carried out over a five year period consistent with EPA's planned second scientific review on fine particles. Dr. Slott's discussion of multiple stakeholder co-sponsored research focused on the need for the following: public technical debates over health effects, accurate transport modeling with a regional rather than local focus on PM, federal funding or subsidy of fine particle monitoring and chemical speciation programs, annual EPA workshops to review chemical speciation data. Finally, he briefly covered the need for regulation of indoor air quality with an emphasis on protecting children from second-hand smoke.

Questions and Discussion:

Q: John Wise, Mobil Oil (ret.) Is the government a stakeholder, and, if so, is there a mechanism for allowing government involvement?

A: State and federal government should be stakeholders. Co-sponsorship and co-funding of research programs by government and other stakeholders is required.

C: Don Pickrell, US Dept. of Transportation Managed health care providers should be included as stakeholders.

Q: Chris Salmi, New Jersey Dept. of Environmental Protection How do you propose to get the implementation plan to work faster?

A: A five year DEADLINE puts a fixed limit on EPA, limits posturing by the stakeholders, and encourages good relations.

Q: Rich Poirot, Vermont Dept. of Environmental Conservation Other multi-stakeholder processes have had clearly defined problems. What incentives are available to bring the stakeholders together in this case?

A: There is a consensus and general concern about the PM problem. The government MAY only propose the problem to the other stakeholders. The models that are available are good but are not well promulgated as yet.

C: Michael Redemer, Texaco Some people do not like the results even when they are available. For example, the Cass results on chemical speciation are interesting. Speciation helps to define who is responsible for emissions. Therefore, contributors to the emissions should want to be stakeholders to help design the experiments.


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Panel Discussion: Issues Confronting States in Meeting Standards

John Bachmann, US EPA (via speaker phone)

John Elston, New Jersey Dept. of Environmental Protection

Jim Price, Texas Natural Resources Conservation Commission

Jason Grumet, NESCAUM

Richard Scheffe, US EPA

The panel discussion started with an introduction of the participants by the moderator, Praveen Amar, followed by opening presentations by each panel member and general discussion.

John Bachmann, US EPA

Mr. Bachmann noted that the PM2.5 standard would likely appear in the Federal Register by Friday, July 18, and that all involved parties should look ahead to what should be done over the next few years. He recognized spatial averaging as a tool for dealing with the regionality of the PM problem and recommended the annual PM standard as the best method for protecting the most people against long-term exposure. The 24-hour standard is seen by EPA as supplementary protection for PM "hot spots" rather than as a tight restriction on emissions.

He further recognized the importance of source attribution and chemical speciation (i.e., sulfates, organics, and nitrates). He asked for clarification from Glen Cass on nitrate levels. Cass stated that nitrate losses in his sampling measurements are comparable to the federal reference method but that losses may decrease as new sampling techniques are used. Mr. Bachmann discussed the role of other regulations in lowering PM levels. For example, acid rain, ozone, and NOx emissions standards will help to lower the sulfates and nitrates levels in PM. In addition, he posed the question "is there a regionality in organics?" but received no specific answer from the floor.

Q: Günter Oberdörster, University of Rochester Dept. of Environmental Medicine A decrease in fine particles mass may be accompanied by an increase in the mass of ultrafine particles. Do you agree?

A: We have modeling results showing no effect on ultrafine particles when fine particles levels are reduced.

C: Oberdörster Data from Germany showed an increase in ultrafine particles in clean air, in which the total mass concentration of particles had gone done. Epidemiological evidence suggested an accompanying increase in asthmatic response.

A: EPA is concerned about this, but in the U.S. the levels of fine particles are lower than in Germany. The effect will not be as dramatic in the U.S.


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John Elston, New Jersey Dept. of Environmental Protection

Mr. Elston presented ozone measurements, and he noted that the ozone regulatory process was cooperative and that the PM process should be the same. He suggested the following regulatory hypothesis: given the current observational data, the probability is good that the Northeast will be able to reach the PM standard in the next few years based on the current Clean Air Act mandates and that the PM standard will become an upper limit. The Northeast will reach attainment of PM standards because of the Acid Rain Phase II, OTAG (ozone), and Reformulated Gasoline Phase II programs.

He gave three examples to support his hypothesis. First, the 1971-1996 Smoke Shade Study, in which atmospheric transmittance was measured at 10 sites in the Northeast and averaged annually, showed a dramatic reduction in particulates in response to a shift from coal to lighter fuel oils and natural gas in the 1970?s. This fuel changeover was the product of state programs, particularly ones to limit sulfur emissions in the Northeast. Likewise, the focus of state control programs from 1971 to 1987 was coarse particulates, but this focus has shifted to fine PM. In the 1990s, the acid rain program has helped to lower particulate levels, although at a slower rate than in the 1970s. Second, the sulfate/nitrate ratio at five sites in New Jersey dropped from 16 in 1969 to 7 in 1995. Third, ozone and fine particles measurements taken in Newark, New Jersey, during June, 1997, showed that fine particles track closely with ozone levels and that both show a dependence on temperature. Mr. Elston noted that these clues strongly suggest that the PM standards can be met in the Northeast.


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Jim Price, Texas Natural Resources Conservation Commission

Dr. Price introduced the topic of PM2.5 monitoring in Texas, noting the cooperative effort in Southeast Texas to determine what the gravimetric levels and chemical speciation data are for that region. He made the point that Texas set up sampling sites in Galveston and Mauriceville to assess PM transport and to address the issue of local versus regional transport. It was his opinion that the US EPA effort to set up monitoring sites as soon as possible was unacceptable without transport and chemical speciation measurements done in parallel. Further, he stated that daily sampling will not protect the public better. A filter-based system is appropriate for routine sampling, and automated sampling would only be desirable if it was accompanied by speciation measurements.

Dr. Price presented data showing the effects of Sahara (or Sahel) dust, transported from North Africa in the summer, on background PM levels in Southeast Texas and Louisiana. This dust incursion happens a few times per year with PM concentrations reaching levels of 20 - 40 mg/m3 and PM mass mean diameters of less than 1 mm. He noted that this event would not violate the PM standard even if it exceeded the 65 mg/m3 24-hour limit. Finally, Price showed satellites images of a haze moving from Texas into the Gulf of Mexico. He indicated that this haze was linked to fine PM and that it occurred during a period of high ozone levels (~170 ppb).

C: Ilhan Olmez, MIT Nuclear Reactor Laboratory In 1996 at Ft. Myers, Florida, we observed four episodes of Sahara dust with PM2.5 levels exceeding 100 mg/m3, of which 25 mg/m3 was aluminum. The amount of material we observed was extensive.

A: Florida typically gets more frequent episodes than the Gulf states.


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Jason Grumet, NESCAUM

Mr. Grumet suggested two topics for consideration: uncertainty and public support. The uncertainty associated with particulate matter is significant, and this notion is publicized by the press. The problem then becomes dealing with the uncertainty without letting inaction or a prolonged (i.e., ten year) study be the result. He suggested that the federal government is positioned to reduce NOx and SO2 based on acid rain regulations and that the costs of reducing SO2 are less than originally predicted. This reduction will benefit PM2.5. Also, given the uncertainty being faced, cost-benefit analysis is a good tool to use in assessing the PM standards. Overall, efforts must be made to have science move forward in an integrated and efficient way to address issues like chemical speciation.

Public support for particulate matter standards is strong based on polling results. As a result, Congress will likely support the standards, particularly since the 24-hour standard (65 mg m-3) is higher than the NESCAUM-recommended 35 mg m3 per day. In general, the American public feels that there is a diesel PM pollution problem based on their observations of buses and trucks. When the government tells the public that no pollution problem exists because no PM standards were violated, the public loses confidence. A democratization of the data is required to make the public aware of the current information. Reporting of local ozone levels by meteorologists is a step toward publicizing the monitoring data. The problem resulting from this reporting, however, is convincing the public that ozone or PM levels that exceed the 24-hour standards on a given day are still safe.


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Richard Scheffe, US EPA

Dr. Scheffe responded to the presentations of the other panel members with a few brief comments. He stated that EPA was planning to implement one to three laboratories for analysis of PM samples and many sampling sites, with the majority in affected communities and some in background locations. Continuous monitoring instruments are required, particularly since the federal reference monitor does not offer continuous measurement. Finally, he pointed out that Sahara dust is not from the Sahara Desert but rather from agricultural regions adjacent to the Sahara.

Questions and Discussion:

Q: Michael Redemer, Texaco With respect to indoor exposure, what are the typical sources? And, what can the public do to help itself? How can the public be informed about indoor exposure?

A: John Elston It is difficult to regulate indoor exposure. The Department of Health is an important player .

A: John Bachmann EPA put out a document on smoke in public places. Compared to ozone which is lower inside buildings compared to outside, PM crosses the indoor/outdoor boundary. The public may not be able to escape high PM level by going inside.

C: Jim Price The public perceives that diesel pollution is a health problem. This may not be the case. Data from studies in which mice were exposed to concentrated diesel exhaust show no respiratory problems associated with the exposure. An aesthetic problem is not necessarily related to a health hazard. PM2.5 is invisible and is not an aesthetic problem, but it may have an important impact on health.

Q: Maybe we need to include the "soft science" of public knowledge and sentiment with the hard sciences in relation to PM. Changes in public behavior may be important. What is the disadvantage to over-controlling PM? How much will this really cost?

A: Jason Grumet There are advantages to starting early. The public tends to pick up on real problems, so we can try to control both nuisance problems and health-related problems. This would be the case for diesel vehicles.

Q: Jeff MacGillivray, NH State Representative How do we get the maximum environmental benefit for our money? Some features of the Clean Air Act do not allow flexibility (e.g., substitution of technology). Is there a prospect of increasing flexibility? Is there a prospect for a market-driven process? Also, can something be done to avoid blaming states for violations when the source of the pollution is an adjacent state?

A: Jason Grumet A combination of altruism and desire for better localized control will help to eliminate the interstate problems.

C: Jim Price Given flexibility, some states may not take the rational or low-cost approach. In 1990, states had not done their jobs with respect to air pollution, so a proscriptive act (Clean Air Act) was written. Annual standards will help to improve background emissions.

A: John Bachmann Administrator Browner is committed to flexibility, and flexibility will apply from the PM standards document.

Q: Ken Colburn, NH Dept. of Environmental Services Although they are better than command and control policies, market-based solutions did not work well for New Hampshire. Is it possible to create a performance standards in industry?

C: Do we need science-based standards or not? To influence the public, we need to convince them that the regulators are acting based on science. How do we bring the public into the process?

A: Ken Colburn Science is important to the decision making process. New Hampshire is in the process of clean air strategy planning, but EPA is a problem for implementing science. New Hampshire was sanctioned for not having a vehicle inspection and maintenance program for control of VOCs, although NOX is a more important pollutant. The Clean Air Act has tied the hands of EPA.

C: Jeff MacGillivray Congress should allow EPA more flexibility in meeting and implementing Clean Air Act mandates.

C: Jason Grumet There needs to better interaction with the public on what constitutes pollution issues. Also, we need to deal directly with inspection and maintenance providers (e.g., service stations, car dealerships, etc.) on implementation strategies. The public has to get involved in understanding the science.

C: Barbara Kwetz, Massachusetts Dept. of Environmental Protection We realized that there is a need to use market research and target groups to understand the public sentiment on pollution issues, like recycling, smoking, etc.

C: Jim Price There is a need to have someone other than government address the public and a need to talk to end sources in advance. An affected community must be given the scientific tools to understand their situation.

C: Joe Mauderly, Lovelace Respiratory Research Institute To clarify the comments made by Jim Price about the effect of diesel exhaust on mice, 3500 mg m-3 had an effect on the mice but it did not affect developing lungs more than mature lungs in mice.

Q: What is EPA?s response to the five year delay, proposed by members of Congress, in implementing the PM standard?

A: John Bachmann EPA is opposed. This is a needless delay that would extend the implementation by more than two or three years. There is a significant difference between having and not having the standard. In either case, however, additional research will be done as long as funds are available.
 
 


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SESSION 3: Frontiers of Health Effects Research

Moderator: Jane Warren

What new data are likely to become available to inform future decisions?

Studies Using Concentrated Ambient Particles

John Godleski, Harvard School of Public Health

Dr. Godleski explained that it is important to study ambient particles, because it is the "right stuff", though it is complex, is subject to day to day variations, and is less reproducible than surrogates. Ambient PM can be studied in the laboratory by:

* in vitro introduction by re-suspension of filtered material. Problems with this include differences in soluble and insoluble fractions, changes in constituents upon collection with the filter, and unknowns in dosage.

* instillation of small amounts of material (solution) into animal lungs

* inhalation using ambient particle concentrators

He described Harvard's ambient particle concentrator: * a virtual impact concept

* concentrates across a spectrum of particle sizes

* concentrates to a biologically meaningful degree

* delivers aerosol to animals at appropriate flows, pressure, etc.

* collects PM2.5 and lower only to 0.1 um (removes UF particles and gases)

* achieves a 30-fold concentration (sulfate concentration is roughly same)

* collection efficiency is higher for larger particles

Dr. Godleski showed that concentrated ambient particles (CAP) have significant toxicity in vitro, and both soluble and insoluble fractions of CAP produce oxidants in hamster lung macrophages, though response is dependent on immediate exposure which changes daily. Inhalation studies have resulted in both local pulmonary and systemic effects in normal and compromised animals. CAP caused lung inflammation and altered heart function in dogs. This may be dose-related, but on 20% of the days studied, the dogs showed no response regardless of dose. In dogs with coronary occlusions, CAP exposure produced changes in the electrocardiogram which are known precursors of ventricular fibrillation. Rats with chronic bronchitis experienced 37% mortality when exposed to CAP, while no deaths were seen in normal rats exposed to CAP nor in bronchitic rats sham exposed. He summarized by stating that ambient particles have an intrinsic toxicity and cause statistically significant pulmonary and cardiac responses.


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Cytokines and Oxidative Stress as Factors in the Lung's Response to Particles

Kevin Driscoll, Proctor and Gamble

Dr. Driscoll described cytokines as protein mediators for the inflammatory response in the lung, which have local and systemic effects and contribute to the pathology of disease. Their functions include initiating inflammation, recruiting inflammatory agents, and resolution.

Rats were introduced to two types of residual oil fly ash (ROFA) in vivo, ROFA#2 having low amounts of leachables and ROFA#6 having high leachable content (mostly vanadium). The results were as follows:

* Lungs introduced to ROFA#2 became inflamed, while ROFA#6 caused greater inflammation.

* The macrophage inflammatory protein 2 (MIP2), a key mediator in lung inflammation and growth factor for epithelial cells, increased with ROFA#2 addition, but more with ROFA#6.

* In alveolar epithelial cells in vitro, only ROFA#6 led to over-expression of MIP2, suggesting that ROFA#6 may directly affect epithelial cells as well as macrophages.

* Nuclear factor kB (NFkB), which stimulates expression of inflammatory cytokines and is activated in response to oxidative stress, could be activated by ROFA#6 and ultrafine Al2O3 particles but not ROFA#2 or fine Al2O3. This effect could be attenuated by an antioxidant.

* Particle exposure stimulates H2O2 production within epithelial cells and is likely dependent on metal concentration. The oxidant may come from the mitochondrial electron transfer process, because mitochondrial inhibitors decrease H2O2 production.

Dr. Driscoll summarized that particle exposure leads to oxidative stress in lungs, which causes local inflammation and a systemic immune response, possibly resulting in cardiac effects.

Questions and Discussion:

Q: Is vanadium the metal of interest?

A: Vanadium has been shown to have an effect on tyrosine kinases. It may be a leap, but the evidence is there.

C: Vanadium is used as a catalyst, thus ending up in fly ash.
 
 


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Role of Metals in the Biological Effects Associated with Air Particulate Matter Exposure

Kevin Dreher, U.S. Environmental Protection Agency

Dr. Dreher first asked which constituents of PM are responsible for the epidemiological effects: acidity, inorganics, organics, physical characteristics, biological components, or co-pollutant interactions. He stated that metal content in fly ash increases as particle size decreases and that on small particles, 80% of metals are present on the particle surface. He divided metals into four categories: water soluble, weak acid soluble, strong acid soluble, and insoluble, the first being the most bio-available and likely to have systemic effects.

He reviewed some of the literature linking metals to toxicity, including:

* Lung tissue metal content has increased 30 fold in the last 30 years in Mexico.

* Soluble metals are responsible for the irritant effect of fly ash.

* In bacteria (in vivo and in vitro), particle size and metal content correlate with infectivity.

* Occupational high exposures show link between metals and acute respiratory distress and death.

* PM correlates with oxidant generation in vitro.

* Transition metals and metal-metal interactions mediate lung inflammation.

* Similar response is seen with particles of same mass but different metal content.

* Excess mortalities are seen with fly ash containing vanadium, nickel, or iron.

* Differences in metal content (not organics or carbon) is linked to pulmonary injury.

He then explained two studies in detail: * High hospital admissions and high PM10 levels in the Utah Valley were well correlated to times when a local steel plant was operational. PM samples were extracted with water, and the extract caused inflammation in animal cells. Inflammatory response correlated with PM10 levels and metal content was highest when PM10 levels were high.

* From PM taken in St. Louis and Washington DC, smaller particles (0.4 - 3.3 mm) had higher sulfate and metal content (mostly lead), were more acidic, and gave a greater response (rat studies, in vivo) than all particles together.

He described mechanistically that metal-containing PM leads to OH radical formation in cells and bio-available vanadium causes alteration of tyrosine kinase homeostasis. These could be caused by oxidative injury from metal redox cycling (in the case of vanadium) or directly from metal response elements (in the case of nickel). He concluded by commenting that exposure, epidemiology, toxicology, pathology, and mechanistic considerations all support consideration that PM metals are important health factors.

Judy Havalack

for Dr. G.Oberdörster

Dr. Oberdorster considered that ultrafine particles (UFP, <50 nm) may be a factor in acute lung injury, as they have a high alveolar deposition efficiency. He stated that UFP can coagulate with fine particles (FP) or with themselves in high concentrations. He pointed out problems with animal models -- with respect to dosimetry, specifically when particles are administered by intratracheal instillation -- doses are always much too high and irrelevant for ambient exposures.

He then demonstrated some experimental observations of UFP:


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SESSION 4

Moderator: Jane Warren

Panel Discussion - What research should be done to provide better information for the PM standard?

Panel Discussion: Effectiveness of Standards in Addressing Health Issues

Joe Mauderly, Lovelace Respiratory Research Institute

Frank Speizer, Harvard Medical School

Ron White, America Lung Association

Fred Miller, Chemical Industry Institute of Toxicology

The panel discussion was started with an introduction of the participants by the moderator, Jane Warren, followed by opening presentations by each panel member and general discussion.

Joe Mauderly, Lovelace Respiratory Research Institute

Dr. Mauderly began by outlining an evaluation of uncertainties in measurement and health effects, and a need for additional PM and health data. He suggested that an air/health program should invest more into a few locations (less than 6) with extensive air monitoring, including measurements of particulate fractions, CAA pollutants, and weather patterns, as well as mortality and morbidity statistics. He stated that although air quality has improved, a similar improvement in health has not been documented but that he believes it is possible. He showed data demonstrating a correlation between high concentrations of ultrafine particles near streets and vehicle counts, but also indicating that the concentrations measured at roadside can vary considerably due to wind speed and direction. He proposed that research into ultrafines should include how they penetrate, distribute, and clear from the body, as well as their cytotoxicity, inflammatory effects, and ability to deliver associated biotoxins to cells.


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Frank Speizer, Harvard Medical School

Dr. Speizer listed unanswered questions regarding mechanisms of particulate effects, including whether the particles alone are responsible for health effects, if size and weight are enough to describe a particle, what surface chemistry exists, which statistical methods should be used in analysis, and how to marry epidemiology, pathophysiology, and exposure to understand the mechanisms. He recommended that future research should coordinate toxicology, epidemiology, clinical studies, and aerometrics with a large scale multidisciplinary field study, establishing multiple centers that can conduct studies that can respond to acute episodes of exposure or opportunities to explore unique exposures.. He suggested a need for long-term, stable funding which should be handled in part by industry, and a buffer between research groups and industry and regulatory agencies.


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Ron White, America Lung Association

In response to Dr. Mauderly's comment that he and other CASAC members had been concerned about the relatively short timeframe for the PM NAAQS review as required by the court order schedule, Mr. White stated that the amount of time for the scientific review component of the PM NAAQS review was unchanged from EPA's proposed schedule, and that it was the regulatory review component of the schedule that was compressed. He posed the following questions: what are the health effects (chronic, acute, mortality, morbidity), who is at risk, what is causing the effects, and is the same thing responsible for all effects? He said there is evidence linking PM to infant mortality and there is a need for information on other subgroups (immuno-compromised, etc.). He stated a need for information on the influence of PM on co-pollutants (particularly ozone), integration of epidemiology and exposure studies, attention to health effects other than mortality (like cardiopulmonary disease), and resources from the private sector for a long-term program supporting the CASAC overview of research needs. He concluded that it is necessary to enact a standard based on the existing body of data while more information is gathered.


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Fred Miller, Chemical Industry Institute of Toxicology

Dr. Miller first gave a brief history of the establishment of the PM10 standard. A 15 µm particle size was recommended as a cut-off for inhalation into the trachea (larger particles would be caught in the nose), but a 10 µm cut was available with existing air samplers. As a result, a PM10 standard was invoked while further monitoring was done. However, he stated that there are not enough data to set an annual PM2.5 standard; only 8 truly independent data sets exist with only 4 showing significant effects. More information is needed about speciation and about what these particles do when they reach the lung. Potentially, billions of dollars could be spent on controlling all PM2.5 when only a few components need to be lowered. He suggested that the 15 µg/m3 annual standard proposed by only 2 of 21 CASAC members is not significantly different from the 17.3 µg/m3 seen in Rochester and thus would have no effect.

Dr. Miller recommended analyzing more recent epidemiological data (since only one study went beyond 1989) to see if current cleaner air still has health problems associated with it. He also suggested finding animal models of the disease process (since much of the acute mortality data is based on COPD, for which smoking is a prerequisite, and since chronic effects are unknown), though he recognized that extrapolation to humans is difficult. Also, allowing current CAA standards to drive down particulate levels is desirable as is doing more monitoring, including meteorology, size, and composition. He stated that not enough dosimetry is known for children or compromised individuals, so the PM2.5 standard may not be adequate for them and that a zero-threshold dose response model assumes that a single particle can kill. Since this is not practical, it makes a biologically plausible lower limit necessary. He acknowledged that the 24-hour standard is justified, but in rationalizing costs, older (usually COPD) individuals are currently assigned a dollar value per life that is too high.
 
 

Questions and Discussion (at the end of the session)

Q: Jeff MacGillivray, NH State Representative What is the most valuable information needed to change control strategies? If dose response is zero-threshold, is there a need for a 24-hour standard? Will we be able to trade off, say, metals for sulfate if toxicities are different?

A: Fred Miller We have exposed humans to milligrams of sulfuric acid with no effect. Dose response curves will likely not be parallel for different compounds, so there will be no trade-offs.

A: Ron White If we define the sources of the emissions, we will not necessarily define a single mechanism that is responsible for all effects, for example, aggravation of asthma. Effects will not be attributable to a "silver bullet."

C: Fred Miller Asthma is most likely exacerbated by coarse rather than fine particles.

C: Frank Speizer Fifty percent of mortalities are from cardiovascular problems, and a substantial number of them do not have COPD. There may be some direct cardiac effects.

Q: Richard Valentinetti, Vermont DEC I'm disappointed in this session. We need to know what research we need to do, not debate whether we need a standard. PM monitors will produce data, but how do we use this data?

C: Robert Slott, Consultant We need a team to outline how to use the next five years most effectively, to define the questions that will guide policy.

C: Lee Alter, NESCAUM We need to define monitoring across the board, which will be difficult. Where will the money come from?

C: Frank Speizer There needs to be measurement work on speciation of exposure in the monitoring setting for the measurements to be useful for future epidemiologic work.

C: Fred Miller Monitoring programs must include indoor sampling.

Q: Should we have a new PM10?

A: Fred Miller We need to tighten PM10 and use a 24 hour PM2.5. There are not enough data nationally on PM2.5, though regionally it may be useful based on chemical speciation.

C: Susanne Hering We need to focus on developing a measurement technique over the next five years.


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Closing Remarks

Glen Cass, California Institute of Technology

Prof. Cass ended the symposium, saying that hundreds of monitors and techniques already exist to elucidate current unknowns and that in New England rural areas are already below the standard. PM2.5 will generate an air quality management program, not a need for drastic controls. He stated that the weak link is in a lack of emissions data, which he considers to be worse than a lack of atmospheric data. He added that the 5-10 year implementation period will include 3-4 years of monitoring, 1-2 years of analysis, and more time to put controls in place.

He concluded with thanks to Emmi Snyder for her hard work in organizing and managing the symposium.


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