Nationwide in the United States, particulates come mostly from , but in urban areas they are derived from vehicles and industrial sources.

non-U. S. sources
roads and construction sites
soil erosion
smoke from burning forests
coal-fired power plants
Since the 1960s, as a result of automobile modifications (as well as other factors), carbon monoxide emissions in the U. S. have declined by more than three-fourths and emissions by more than 95 percent.

nitrogen and oxygenated
sulfur dioxide and bicarbonate
hydrocarbon and sulfur dioxide
nitrogen oxide and hydrocarbon
nitrogen hydroxide and oxygen
What would be the best way to reduce the amount of carbon monoxide and nitrogen oxide air pollution?

find ways to reduce emissions from miscellaneous rural and natural resources
find ways to reduce emissions from vehicles
find ways to reduce emissions from other industrial fuel combustion
find ways to reduce emissions from electric utilities
find ways to reduce emissions from industrial processes