US Clean Air Act monitors and controls 6 criteria pollutants and more, stating allowed concentrations for the pollutants
- Sulfur Dioxide
- Nitrogen oxides
- Carbon monoxide
- Particulate matter
- Lead
- Ozone
- VOCs
- Mercury
- Carbon dioxide
Sulfur Dioxide
- SO2
- Corrosive gas that comes from combustion of fuel
- Respiratory irritant
Nitrogen Oxides
- NOx
- Can transform from NO to NO2 easily
- 78% of atmosphere contains N2
- From motor vehicles
- Helps form ozone
Carbon Oxides
- CO
- Colorless, odorless gas
- Formed during INCOMPLETE COMBUSTION
- Dangerous indoor pollutant
- CO2
- Colorless, odorless gas
- formed during COMPLETE COMBUSTION
- Been rising increasingly
PM
- Particulate matter
- Solid or liquid particles suspended in air
- Comes from combustion of biofuel
- PM 10 are harmful as they are not filtered out by our noses
- PM 2.5 are even worse
- PM can also scatter and absorb sunlight
Photochemical Oxidants
- Oxides remove electrons from other chemicals
- Photochemical oxidants
- Air pollutants formed from as a result of sunlight acting on compounds such as NOx
- O3
- In presence of SOx and NOx, photochemical oxidants can enhance formation of certain particulate matter
- Smog
- Air pollution that is mix of oxidants and PM
- Los Angeles type smog
- London type smog
Lead and other metals
- Pb is a trace metal, occurring naturally in rocks
- Was added into car fuel, but later removed
- Still present in paints
- Neurotoxin
- Hg is another trace metal found in oil and fuel
VOCs
- Organic compound that evaporates at typical temp.
- Hydrocarbons
- Play important role in formation of Photochemical smog
- Not hazardous directly