| Term | Definition |
|---|---|
| Atmosphere | the mixture of gases that surround earth |
| ozone | A form of oxygen that has 3 oxygen atoms in each molecule instead of the usual 2; it is a toxic form of oxygen |
| Air pollution | a change to the atmosphere that has harmful effects |
| emissions | solid particles and gases released into the air from a smokestack or motor vehicle |
| photochemical smog | a brownish haze that is a mixture of ozone and other chemicals fromed when nitrogen oxides, hydrocarbons, and other pollutants react with one another in the preasants of sunlight |
