→ Review of the Primary National Ambient Air Quality Standards for oxides of nitrogen

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The Environmental Protection Agency has reviewed the air quality criteria addressing human health effects of oxides of nitrogen and the primary national ambient air quality standards for nitrogen dioxide. There are two primary standards for oxides of nitrogen: (1) a 1-hour standard established in 2010 at a level of 100ppb, and (2) an annual standard set in 1971 at a level of 53 ppb. The Clean Air Act requires the Environmental Protection Agency to periodically review the science upon which these standards are based, and the standards themselves. Based on the most recent review, the Environmental Protection Agency is proposing to retain the current standards, without revision.