Air Pollution Standards

From Thermal-FluidsPedia

Revision as of 00:18, 29 June 2010 by Administrator (Talk | contribs)
Jump to: navigation, search

Air Pollution Standards 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 8-13). 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 Figure 8-13 Comparison of the emissions for six criteria pollutants in the United States for the period 1970-2000. Source: Environmental Protection Agency, 140120100806040200250200150100500CO(-25%)NOX(+20%)VOC(-43%)SO2(-44%)PM(-88%)Pb(-98%)19702000Million tonsThousand tons 26 Cooper, C. D., Alley, F. C., “Air Pollution Control-A Design approach,” Waveland Press, Inc., 1994. 197 Chapter 8 - Air Pollution 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 8-2 compares the current guidelines established by the WHO and the US EPA for various pollutant concentrations and exposure times. Example 8-1: A monitoring station near a coal power plant measures sulfur dioxide concentrations of 200 mg/m3 between the hours of 7:00 am and 5:00 pm. It drops to 60 mg/m3 at all other times. Determine whether this power plant satisfies the WHO’s guidelines. Solution: Within any 24-hour period, the power plant emits 200 mg/m3 for 10 hours of operation and 60 mg/m3 for the remaining 14 hours. The average 24-hour emission is calculated as: Average Daily Concentration = = 118 mg/m3(10x200)+(14x60)24 Although the power plant does narrowly meet the WHO’s guidelines in any 24-hr average, unless there is a considerable downtime, the power plant is likely to exceed the 1-year average emission guidelines. Geographical areas that do not meet the emission standards are called non-attainment areas.


Further Reading

External Links