Air Pollution Standards

From Thermal-FluidsPedia

Figure 1 Comparison of the emissions for six criteria pollutants in the United States for the period 1970-2000.

There are no air pollution standards that are universally adopted by all countries. The World Health Organization (WHO) has provided Air Quality Guidelines for key pollutants (SO2, NO2, CO, O3, and lead) to enable countries to set their national or regional air quality standards within the context of existing environmental, social, economic, and cultural conditions.

Because air pollution does not recognize any boundaries, various states and governments must establish guidelines that regulate interstate and inter-continent pollution transport. In the United States, the agency responsible for setting, monitoring, and enforcing air quality standards is the Environmental Protection Agency (EPA). Congress has empowered the EPA to enact the Clean Air Act (CAA), passed in 1963 and amended in 1970, 1977, and 1990, to develop National Ambient Air Quality Standards (NAAQS) to set criteria for improving average air quality at the federal level. Individual states can set more stringent standards if they desire. Furthermore, it is each state’s responsibility to develop state implementation plans that set the procedure to achieve the state and federal goals. As a result of more and more stringent regulations, US air quality has continuously improved since 1970 when the EPA was established (See Figure 1).

Table 1. Guidelines for Common Pollutants
		WHO	US EPA
Pollutant	Exposure time	Concentration (μg/m3)
CO	15 min 30 min 1 hour 8 hours	100,000 60,000 30,000 10,000	--- --- 40,000 10,000
NO2	1 hour 1 year	400 40	--- 100
SO2	10 min 24 hour 1 year	500 125 50	--- 365 80
O3	1 hour 8 hour	175 110	235 157
PM2.5	24 hours 1 year	--- ---	65 15
PM10	24 hours 1 year	--- ---	50 50
Lead	1 quarter 1 year	--- 0.5

Each of the criteria pollutants is assigned a primary standard intended to set limits that protect health and a secondary standard intended to protect public welfare by preventing environmental and property damage. For areas already cleaner than NAAQS, a three-tiered system has been established to prevent significant deterioration of air quality. In Tier 1 regions (mainly national parks), the emission levels were frozen at their 1997 level when the air quality standards were established. Tier 2 included most regions and allowed some reduction in air quality, whereas the quality of the Tier 3 regions could eventually deteriorate to the minimum air quality standards. Table 1 compares the current guidelines established by the WHO and the US EPA for various pollutant concentrations and exposure times.

References

(1) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005

Further Reading

Gore, A., An Inconvenient Truth, Penguin Books, 2007.

Roleff, T., Pollution: Opposing viewpoints, Greenhaven Press, 2000.

Walsh, P. J., Dudney, C. S., Copenhave, E. D., Indoor Air Quality, CRC Press, 1984.

Environmental Science and Technology, published by the American Chemical Society.

External Links

Environmental Protection Agency (http://www.epa.gov).

Occupational Safety and Health Administration (OSHA) (http://www.osha.gov).

Intergovernmental Panel on Climate Control (IPCC), (http://www.ipcc..ch).

United Nations Environment Programme (http://www.unep.org).

World Health Organization (WHO) (http://www.who.ch).