Air composition and pollutants
The air
- Clean, dry air is about:
- 78% nitrogen,
- 21% oxygen,
- ~1% noble gases and carbon dioxide.
Practice
Clean dry air is about:
Air is roughly 78% nitrogen, 21% oxygen, and about 1% other gases.
Pollutants and their sources
| Pollutant | Source |
|---|---|
| carbon dioxide | complete combustion of fuels |
| carbon monoxide + particulates | incomplete combustion |
| methane | rotting plants, animal digestion |
| oxides of nitrogen | car engines |
| sulfur dioxide | burning fuels containing sulfur |
Practice
Incomplete combustion of a carbon fuel produces:
With too little oxygen, fuels make toxic carbon monoxide and soot particulates.
Their effects
- CO₂ and methane — greenhouse gases → global warming.
- carbon monoxide — toxic.
- particulates — breathing problems, cancer.
- oxides of nitrogen and sulfur dioxide — acid rain.
Practice
Which pollutants cause acid rain? (Choose all that apply.)
Sulfur dioxide and oxides of nitrogen cause acid rain; carbon dioxide is a greenhouse gas.
You've got it
Key idea
- air ≈ 78% nitrogen, 21% oxygen, ~1% other
- incomplete combustion → carbon monoxide + particulates; sulfur fuels → sulfur dioxide
- greenhouse gases (CO₂, methane) warm the planet; SO₂ + nitrogen oxides cause acid rain