Health Effects: Short-term exposure may cause increased respiratory illness in young children and harm lung function in people with existing respiratory illnesses. Long-term exposure may lead to increased susceptibility to respiratory infection and may cause alterations in the lung. (Nitrogen oxides also can be transformed in the atmosphere to ozone of fine particulate soot - which are both associated with serious adverse health effects.)

Environmental Effects: Nitrogen oxides help form acid rain. In addition, this pollutant can cause a wide range of environmental damage, including visibility impairment and eutrophication - that is, explosive algae growth which can deplete oxygen in water bodies such as the Chesapeake Bay.

Sources: Cars, trucks and electric power plants are dominant sources. Home heaters and gas stoves can produce nitrogen dioxide inside homes.