PAN (Peroxyacytyl nitrate) - C2H3O5N
PAN forms when some other kinds of chemicals get together in the air. One of the chemicals that makes PAN is nitrogen dioxide (NO2). Nitrogen dioxide comes from the engines of cars and trucks and from factories and power plants that burn coal. Other chemicals that help make PAN are called Volatile Organic Compounds (VOCs). VOCs get into the air from paint, gasoline, and other chemicals. Sunlight changes the VOCs into other chemicals. Those chemicals get together with oxygen and nitrogen dioxide to make PAN.