Maintaining Air Quality
Air composition, pollutant sources and effects, the carbon cycle and greenhouse gases.
The lessons below are in teaching order. Work through them in turn, then come back after practice and use the outcomes on this page to choose what to review. Finishing a topic records participation only. Check your progress to see what you can answer independently and what to review next.
Lessons in order
- Air Quality, Carbon Cycle and Climate
Learn air composition, pollutant source–effect chains, the carbon cycle, greenhouse gases and global warming.
Learning goals
- describe the volume composition of gases present in dry air as being approximately 78% nitrogen, 21% oxygen and the remainder being noble gases (with argon as the main constituent) and carbon dioxide
- name some common atmospheric pollutants, e.g. carbon monoxide; methane; nitrogen oxides (NO and NO2); ozone; sulfur dioxide; unburned hydrocarbons
- state the sources of these pollutants as — carbon monoxide from incomplete combustion of carbon-containing substances
- state the sources of these pollutants as — nitrogen oxides from lightning activity and internal combustion engines
- state the sources of these pollutants as — sulfur dioxide from volcanoes and combustion of fossil fuels
- discuss some of the effects of these pollutants on health and on the environment — the toxic nature of carbon monoxide
- discuss some of the effects of these pollutants on health and on the environment — the role of nitrogen dioxide and sulfur dioxide in the formation of ‘acid rain’ and its effects on respiration and buildings
- describe the carbon cycle in simple terms, to include — the processes of combustion, respiration and photosynthesis
- describe the carbon cycle in simple terms, to include — how the carbon cycle regulates the amount of carbon dioxide in the atmosphere (see also 8.1(d))
- state that carbon dioxide and methane are greenhouse gases and may contribute to global warming; give the sources of these gases and describe the potential effects of increased levels of these greenhouse gases, including more extreme weather events and melting of polar ice.