ABSTRACT
In order to provide metrics to assess air quality, standards have been defined by both federal and state agencies. These standards are defined in terms of concentration levels for specific periods and pollutants that can be easily and routinely measured. They are developed based on effects data and are primarily designed to protect human health and welfare. Currently, there are seven criteria pollutants covered by the federally mandated National Ambient Air Quality Standards (NAAQS) (Table 9.1). These include: ozone (O3), respirable particulate matter (PM10, particulate matter with aerodynamic diameter less than 10 μm), fine particulate matter (PM2.5, particulate matter with aerodynamic diameter less than 2.5 μm), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and lead (Pb). Federal primary standards provide a margin of safety to protect human health. Secondary standards are designed to protect health and welfare from known and anticipated impacts. Currently only SO2 has a secondary standard that differs from the Federal primary standard.
