g o v e r n m e n t

EPA Issues Guidance On Ozone, Particulates Rules Linda Ross Raber C&EN Washington

Ababy born today will be heading off to college by the time the new na-1 tional ambient air quality standards

for ozone and particulate matter are fully implemented. By the time the baby's par­ents decide how to redecorate the "extra" bedroom, the standards, designed to allevi­ate asthma in children and pulmonary dis­ease in the elderly, will have likely been reviewed—and maybe changed—two more times. So far, the final target date for compliance with the new particulate stan­dard is 2017.

At least that's the scenario based on the latest guidelines from the Environ­mental Protection Agency, which in July 1997 revised the national ambient air quality standards for ground-level ozone and airborne particulate matter. These guidelines give states and other affected entities information on how and when the standards will go into effect.

Ozone at ground level is the primary constituent of smog. It is a respiratory ir­ritant and causes harm to some crops. Unlike other pollutants, it is not emitted directly into the air; rather, it is formed when volatile organic compounds (VOCs) and nitrogen oxides (NOx) react on hot days in bright sunshine.

NOx gases are produced by burning fossil fuels, mostly from highway vehi­cles and large industrial power plants like those run by the electric utilities.

Specifically, the one-hour ozone stan­dard is being phased out, and an eight-hour standard, thought to be more repre­sentative of human exposure, is replacing it. The new standard sets a maximum con­centration of 0.08 ppm ozone averaged over eight hours. This is considerably more stringent than the previous standard.

Rather than simply lumping half the U.S. into a "nonattainment" category, as might have been the case given the strin­gency of the new standard, the guidance sets up a scheme by which areas that are not meeting either the one-hour or the eight-hour or both ozone standards will be assigned to specific categories depending on where their ozone comes from.

The guidance also coordinates imple­mentation of the ozone standard with upcoming NOx reductions required of

the 22 easternmost states and the District of Columbia. When fully implemented, the rule aims to reduce emissions of NOx in the East by 1.6 million tons per year.

According to EPA, many areas will need little or no additional new local emis­sion reductions to meet the ozone stan­dards beyond the reduction achieved through controlling NOx. And the agency anticipates that these areas most likely will come into attainment earlier than other­wise required.

The new guidance spells out that EPA will divide areas that violate the eight-hour ozone standard into three catego­ries depending on whether the pollution that exists in a specific locality actually originates within that locality or even in that state. Areas that now meet the one-hour standard but are not expected to soon meet the eight-hour standard will be labeled "transitional areas." These ar­eas are expected to be pretty much the same areas that are affected by the NOx reduction requirements.

The transitional classification described in the guidance document is the primary element of EPA's flexible implementation approach for ozone. According to the guidance document, "This classification

Extended schedule for meeting new air rules aims to ease state burdens

OZONE 1999—State implementation plans

for NOx due 2000—Final compliance classifica­

tions made 2003—Attainment date for all transi­

tional areas 2005—Attainment date for areas that

fail 2003 attainment; attainment date for international transport areas

2007—State NOx budgets fully achieved 2010—Attainment date for most se­

vere ozone problem areas

PM25 1999^-Monitoring network in place 2003—Monitoring data collection

completed 2005—Nonattainment areas designated 2008—State implementation plans due 2017—Latest date for compliance

encourages cleaner air sooner, [and] re­sponds to the fact that ozone is a regional as well as a local problem." It is designed to allow states to take advantage of man­dated regional NOx reductions and likely will make it easier to comply with the new ozone standard.

The second category for areas not meeting the standard will be called "inter­national transport areas." This classifica­tion will be reserved for areas that can show that they are in violation of the stan­dard because of transported emissions that come from non-U.S. sources. These areas will still have to meet the standards but will be given more time to do so.

Areas failing to meet the standard and falling into neither the transitional nor the international transport areas would be called "traditional" nonattainment areas and would have their own schedules of compliance. Areas with particularly severe ozone problems will have much extended schedules for attainment.

For example, EPA anticipates that this approach will apply to the San Francisco Bay Area, which EPA just redesignated from attainment to nonattainment for the one-hour ozone standard. This area will have un­til November 2000 just to meet the less stringent one-hour standard. Full compli­ance with the eight-hour standard will likely be required for that area in 2010.

In addition, for the first time, the re­vised national ambient air quality stan­dards establish regulations for ultrafine air­borne particulate matter that is less than 2.5 pm in diameter—PM25. These tiny particles and droplets are thought to pene­trate lung tissue more deeply than larger particles. They may also be associated with ill health and even death in some sus­ceptible populations, although the evi­dence implicating the particles isn't clear.

The new fine particulate rule sets an annual limit on the mass of PM2 5 in the air to 65 μg per cubic meter, with a daily limit of 15 μg per eu m.

Airborne particulate matter comes from natural processes and human activ­ities. Some sources are forest fires, wind erosion, farming, fossil fuel combustion, and manufacturing. EPA has not yet col­lected enough information on PM2 5 to give a lot of detail on how compliance will be achieved. The agency is required to set up a nationwide network of PM2 5 monitors and to collect three years' worth of data before it makes attainment designations for any area.

The new guidance documents can be downloaded at http://ttnwww.rtpnc. epa.gov/implement/actions.htm. M

SEPTEMBER 7, 1998 C&EN 27