Nitrogen dioxide is formed during combustion processes that create extremely high temperatures, such as those that result from burning coal, oil, and gas fuels, and from burning fuels in motor vehicle engines. Nitrogen oxides are necessary for the formation of ground level ozone and can contribute to acid rain. The human respiratory system is susceptible to effects caused by exposure to nitrogen dioxide. Asthmatics are particularly sensitive to these effects. 

Monitoring results show that ambient nitrogen dioxide levels have remained near the 0.02 parts per million (ppm) level since 1992, which is less than one-half of the standard. Michigan has never recorded a violation of the nitrogen dioxide standard. Michigan has been in attainment for nitrogen dioxide since March 3, 1978. 

EPA's NO2 Designations Letter to Michigan's Governor January 2012
EPA's NO2 NAAQS 120 Day letter to Michigan (6/28/2011)
Michigan's Designation Recommendation to EPA (9/14/2009)

Other Resources: 

• Nitrogen Dioxide Attainment Map 
• Nitrogen Dioxide Monitoring 
• Nitrogen Dioxide Real-Time Data 
• EPA's Final Rule for NO2 NAAQS
• EPA's Proposed Rule for NO2 NAAQS 

Recommended EPA Resources: 

• NOx - How Nitrogen Oxides Affect the Way We Live and Breathe 
• National Air Quality Status and Trends: Nitrogen Dioxide (NO2) - Nitrogen dioxide is a reddish brown, highly reactive gas that is formed in the ambient air through the oxidation of nitric oxide. 
• Nitrogen Dioxide - Nitrogen dioxide (NO2) belongs to a family of highly reactive gases called nitrogen oxides (NOx).