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For nitrogen dioxide (NO 2), the guidelines set 10 μg/m 3 for the annual mean or 25 μg/m 3 for a 24-hours mean. [2] For sulfur dioxide (SO 2), the guidelines stipulate concentrations not exceeding 40 μg/m 3 24-hour mean. [2] For carbon monoxide concentrations not exceeding 4 mg/m 3 24-hour mean. [2]
The Clean Air Act requires the EPA to set US National Ambient Air Quality Standards (NAAQS) for the six CAPs. [6] The NAAQS are health based and the EPA sets two types of standards: primary and secondary. The primary standards are designed to protect the health of 'sensitive' populations such as asthmatics, children, and the elderly.
The CSAPR requires 23 United States states to reduce their annual emissions of sulfur dioxide (SO 2) and nitrogen oxides (NO x) to help downwind states attain the 24-hour National Ambient Air Quality Standards, and 25 states to reduce ozone season nitrogen oxide emissions to help downwind states attain the 8-hour NAAQS.
The National Ambient Air Quality Standards (NAAQS) govern how much ground-level ozone (O 3), carbon monoxide (CO), particulate matter (PM 10, PM 2.5), lead (Pb), sulfur dioxide (SO 2), and nitrogen dioxide (NO 2) are allowed in the outdoor air. [6] The NAAQS set the acceptable levels of certain air pollutants in the ambient air in the United ...
As an example, the United States Environmental Protection Agency has developed the National Ambient Air Quality Standards (NAAQS) [6] NAAQS set attainment thresholds for sulfur dioxide, particulate matter (PM 10 and PM 2.5), carbon monoxide, ozone, nitrogen oxides NO x, and lead (Pb) in outdoor air throughout the United States.
In the United States, the emission standards for non-road diesel engines are published in the US Code of Federal Regulations, Title 40, Part 89 (40 CFR Part 89). Tier 1–3 Standards were adopted in 1994 and was phased in between 1996 and 2000 for engines over 37 kW (50 hp). In 1998 the regulation included engines under 37 kW and introduced ...
By contrast, the second three tree species, oak, beech and hickory, are associated with microbes that "absorb reactive nitrogen oxides," and thus can have a positive impact on the nitrogen oxide component of air quality. Nitrogen oxide release from forest soils is expected to be highest in Indiana, Illinois, Michigan, Kentucky and Ohio. [19]
Many countries monitor ground-level ozone, particulates, sulfur dioxide, carbon monoxide and nitrogen dioxide, and calculate air quality indices for these pollutants. [12] The definition of the AQI in a particular nation reflects the discourse surrounding the development of national air quality standards in that nation. [13]