Testimony of
Dr. Phillip J. Wakelyn

On Implementation of the New Clean Air Regulations and Their Impact on the Agriculture Industry

Before the Senate Agriculture, Nutrition and Forestry Committee
Washington, D.C.

July 22, 1997

 The agriculture production and processing industries continue to have many unresolved concerns about the new standards for particulate matter (PM) and ozone finalized by the Environmental Protection Agency (EPA) on Friday, July 18, 1997. These new standards could result in unnecessary and costly control measures and many costly indirect economic impacts on farmers and agriculture processing. Energy and fuel costs are fifty percent of the cost of producing an agricultural commodity.

First it is important that everyone understands what particulate matter (PM)/PM 2.5 is and what the sampler approved by EPA measures. Most people do not appreciate the complexity and variability of particulate matter. It is generally understood when one measures a specific chemical like ozone that ozone is three oxygen atoms bonded together and that at different places and times we measure a different concentration. PM 2.5 also varies in concentration. Additionally, however, the chemical composition and the size and size distribution of those particles change and we do not obtain this information from the newly approved EPA sampling method published on July 18, 1997 (62 FR 38714). Another way of saying this is that you can not write a chemical formula for PM 2.5 as you do for ozone (O3) or sulfur dioxide (SO2).

PM varies in chemical composition and particle size distribution in every area of the country. PM 2.5, or fine particulate, can be sulfates, nitrates, organic matter (organic carbon compounds), elemental carbon (soot), and soil dust (crustal materials). The relative fractions of these components vary from place to place and over time (with seasons). In addition to characterizations by size and chemical composition, particles can be described by their formation origin, physical properties and by sampling/measurement technique. EPA indicates that about half to two-thirds of the fine particulate is secondary particulate which is formed in the atmosphere and transported sometimes long distances. For example, according to EPA diesel fuel exhausts from Los Angeles can result in particulate causing haze over the Grand Canyon and there are publications which show that fine particulate from the Sahara Desert can be measured in various parts of the U.S. The atmospheric chemistry for the formulation of secondary particulate is very complex. The amount formed and transport are postulated from theoritical models, not actually known or measured.

On Friday, July 18 (62 FR 38714) EPA also finalized the sampler and reference method for determining fine PM as PM 2.5 in the atmosphere (40 CFR 50, Appendix L). The new reference method for PM 2.5 contains a combination of design and performance specifications to define the sampler. In other words it is a PM 2.5 sampler "by design". It does not measure only particulate 2.5 microns and below. The "cut point" or "particle discrimination technique" used for this sampler is only about 50% efficient at collecting particles 2.5 microns and below. Because the samplers have a collection efficiency that varies around the 50% cut point, particles greater than 2.5 microns will be collected. In fact some researchers have found particles as large as 60 to 70 microns (PM 60 and 70) on filters using prototypes of the newly approved sampler.

Further on the sample, on July 18, 1997 (62 FR 38762) EPA announced the availability of "certain laboratory and field test data and related reports associated with the reference sampler" and are having a supplemental comment period for the purpose of taking comments on these data. These tests did identify areas needed for modification of the sampler and EPA is giving the public one month to comment on the new information. Therefore, it appears that EPA has promulgated a new standard for PM 2.5 for which no measurements have been made with an approved sampling instrument. EPA is still changing the sampling instrument and has not characterized what the sampler actually measures. This is the sampler that will be used to determine whether an area is non-attainment for PM 2.5 and a facility's PM 2.5 emissions.

What does this mean for agriculture? Agricultural particulate from soil is only generally about 1 to 2% PM 2.5 and below if actual particle size distribution measurements are made on samples captured on filters. However, using the approved sampler agricultural dust could be as high as 10, 15, or even 20% PM 2.5. EPA's own information suggests that agricultural dust could be about 34% of primary PM 2.5 (particles directly emitted into the air), which is about one-third to one-half of the total PM 2.5 produced according to EPA. Also agriculture can produce some of the secondary PM 2.5 (particles formed in the air from gaseous pollutants). So by EPA's own estimates agriculture can be 15% or more of the PM 2.5 problem. Because of what the EPA sampler actually collects, expensive control measures could be required unnecessarily for agriculture. In addition, according to Dr. Calvin Parnell, Texas A&M University, the current level of technology in the design of air pollution controls does not control PM 2.5.

In news releases and press conferences, EPA always refers to PM 2.5 as microscopic soot primarily from combustion. If EPA is truly interested in PM 2.5 then that is what should be accurately measured and the source of the PM 2.5 accurately determined. Otherwise the new rules could result in unnecessary and costly control measures for agriculture. In a June 5, 1997 letter to Sen. Lugar, EPA Assistant Administrator for Air and Radiation Mary Nichols stated that "since secondary PM 2.5 is formed in the atmosphere and often transported long distances, PM 2.5 air monitoring data should be chemically analyzed and broken down into individual chemical species and then used to determine emissions sources." In addition, EPA has said (62 FR 38668; July 18, 1997) that they will evaluate in the context of implementation policies "methodology that would extract coarse mass from PM 2.5 measurements where undue coarse particles intrusion results in fine standard violations". We agree that there is a need to speciate (chemically analyze) and size segregate samples. This information would be valuable in determining whether the PM 2.5 sample is innocuous or toxic, where it comes from, and what to do about it. EPA's approved reference sampler only gives a gravimetric sample, i.e., a mass on a Teflon filter. There are other samplers and methods that are helpful in obtaining speciation and size information. EPA says (62 FR 38698; July 18, 1997) that "innovations and improved samplers or measurement methods are encouraged and provided for as Class II and III equivalent methods (see 40 CFR 53)". EPA should allow other samplers and analysis techniques to be used to prevent unnecessary and costly control measures being required. This is particularly true for agriculture.

No perfect method for capturing and determining all the chemical characteristics of ambient PM aerosol is currently in use and that method may not presently exist. EPA should encourage development of new, improved ambient PM measurement techniques in light of the needs of state and local air quality planning requirements.