National Emission Standards for Hazardous Air Pollutants in the United States
National Emission Standards for Hazardous Air Pollutants (NESHAPs) in Environmental Law
Regulations that set standards for hazardous air pollutants, also called air toxics. They are mandated by the Clean Air Act, which was enacted in 1970. However, hazardous air pollutant regulations changed fundamentally with the passage of the Clean Air Act Amendments of 1990.
Pre1990 Law
In 1970 the Environmental Protection Agency (EPA) was charged by the Clean Air Act to list air pollutants that “may reasonably be anticipated to result in an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness.” After the pollutants were listed, the EPA was required to develop standards that were stringent enough to protect human health with “an ample margin of safety.”
By 1990, the EPA had listed only eight substances as hazardous air pollutants: asbestos, benzene, radionuclides, inorganic arsenic, coke oven emissions, vinyl chloride, and beryllium. Standards had been established for all but coke oven emissions, but the standards were not applicable to all of the sources that discharged them.
An article in the Environmental Law Reporter lucidly explains some of the reasons for the EPA’s failure to do more. First, most people assumed that emissions of hazardous air pollutants affected workers, not the public, and regulation of the workplace is the job of the Occupational Safety and Health Administration. Second, the EPA seemed uncertain what level of control was necessary under the Clean Air Act. Many substances could be said to be hazardous enough to require a zero exposure limit, but if the standards were set at zero, they could eliminate many businesses and products. The law was ambiguous concerning whether the EPA could consider the cost of meeting the standards when it made its determination. Finally, modeling done by the EPA when determining health effects is extremely conservative. It assumes a person is exposed to a constant level of the pollutant twenty-four hours per day in the same location for seventy years. The model does not yield a realistic estimate of minimim controls necessary.
Awareness of the need for more regulation of hazardous air pollutants coincided with the release of the Toxic Release Inventory in 1989. The EPA compiled the inventory using numbers reported by industry concerning emissions of hazardous substances. Industries had not been required to monitor and report those emissions until the Emergency Planning and Community RightToKnow Act was passed in 1986. But once the inventory had been compiled, the public (and Congress) knew at last that hazardous air pollutants pose health problems outside of the workplace.
Changes in the Program
The Clean Air Act Amendments of 1990 immediately changed the focus of the air toxics regulations from attempting to establish what air toxics were to regulating them, since it included its own list of 189 hazardous substances or classes of substances. (The EPA may add to the list or delete from it by going through a regulatory review.) Congress also determined that the EPA may consider cost of technology when setting the limits.
The amendments also require the EPA to list the types of industries that may be considered major sources or area sources of hazardous air pollutants. Major source for the purpose of regulating air toxics is any stationary facility capable of emitting ten tons or more per year of one hazardous air pollutant or twenty-five tons or more per year of any combination of hazardous air pollutants. Approximately 7,000 sources are regulated as major sources of air toxics.
Area sources are smaller stationary sources. However, their combined emissions may create a problem within an air quality control region. Examples of area sources include wood stoves, dry cleaners, service stations, water treatment facilities, and solid waste disposal facilities. Individually they may not emit enough hazardous air pollutants to place them into the major source category, but together they may contribute significant amounts of air toxics.
Standards under the amended Clean Air Act are technology based rather than health based, and most are expressed in terms of emission limits. However, the EPA may promulgate standards based on work practices, design standards, or equipment if emission standards cannot be developed.
The EPA must require major sources to use the maximum achievable control technology (MACT) to achieve compliance with the limits. Contrary to what the term implies, MACT does not usually mean that a specific type of technology is required. Instead, the EPA establishes emission standards after considering what that technology can accomplish. The new emission standards are to be phased in by 2000.
Area sources have a lesser burden. They must comply with emission levels set with reference to generally available control technology or GACT. However, the EPA’s first priority is to establish MACT It is required by the statute to develop an area source program by November 1995. The appropriate control measures will follow the publication of the area source program.
After the appropriate technology has been applied, some risk from the emissions may remain. The EPA is directed to calculate the risk, determine the health significance, consider methods of further control and costs, and examine the actual health effects. Recommendations must be made to Congress based on the EPA’s conclusions. If Congress does nothing, the EPA must set emission standards to deal with residual risks by 1998.
Based on “Environment and the Law. A Dictionary”.