Respirable particles less than 10 microns in size

Aggravates ailments such as bronchitis and emphysema, especially bad for those with chronic heart and lung disease as well as the very young and old, and pregnant women

An odorless, tasteless, colorless gas which is emitted primarily from any form of combustion

Deprives the body of oxygen by reducing the blood's capacity to carry oxygen, causes head-
aches, dizziness, nausea, listlessness, and in high doses, may cause death

A toxic gas associated with photochemical smog; formed when nitrogen oxides and volatile organic compounds photochemically react with each other in the presence of sunlight and warm temperatures

Volatile organic compounds and nitrogen oxides from:

Irritates eyes, nose, throat and respiratory system; especially bad for those with chronic heart and lung disease as well as the very young and old, and pregnant women

A poisonous gas produced when nitrogen oxide is a byproduct of sufficiently high burning temperatures.
Precursor to ozone formation.

Combustion processess:

Harmful to lungs, irritates bronchial and respiratory systems; increases adverse symptoms in asthmatic patients

A pungent, colorless gas that combines with water vapor to become sulfurous acid (H₂SO_{3 ),} a mildly corrosive compound; when sulfurous acid combines with oxygen, it produces sulfuric acid (H2SO4 ), a very corrosive and irritating chemical

Increases the risk of adverse symptoms in asthmatic patients: irritates respiratory system; harmful to plant life; dissolves stone and corrodes iron and steel

A widely used metal, which may accumulate in the body

Disturbs motor function and reflexes, impairs learning, causes intestinal distress, anemia and damage to the central nervous system, kidneys and brain. Children more adversely affected than adults