What pollutes the air, and how it causes global warming, acid rain and ozone loss.
Sources and effects of air pollution. Video coming soon.
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A pollutant is a substance in the wrong place or amount that harms living things or the environment. Major air pollutants: carbon monoxide (incomplete burning of fuels, which binds to haemoglobin), oxides of sulphur and nitrogen (burning coal and petrol), particulate matter (smoke, dust), hydrocarbons and chlorofluorocarbons (CFCs, from refrigerators and aerosols). Sources are vehicles, industries, thermal power plants and burning of waste.
Why is carbon monoxide poisonous?
It combines with haemoglobin more strongly than oxygen does, so blood carries less oxygen.
Name a source of sulphur dioxide.
Burning coal and petroleum containing sulphur, and smelting of ores.
What is particulate matter?
Tiny solid or liquid particles such as soot and dust suspended in air.
The greenhouse effect is natural warming by gases such as CO₂, CH₄ and water vapour that trap heat. Extra emissions strengthen it and cause global warming, melting ice and rising sea levels. If CO₂ rises from 280 to 420 ppm, that is a 50% rise. The ozone layer in the stratosphere absorbs harmful ultraviolet rays; CFCs release chlorine that breaks ozone down, and the loss raises skin cancer and cataract risk.
Carbon dioxide rose from 280 ppm to 420 ppm. Find the percentage increase.
(420 − 280) ÷ 280 × 100 = 50%.
Name two greenhouse gases.
Carbon dioxide and methane.
How does the ozone layer protect us?
It absorbs most of the Sun's harmful ultraviolet radiation.
Oxides of sulphur and nitrogen dissolve in rain to form sulphuric and nitric acids, giving acid rain (pH below 5.6). It corrodes marble monuments, damages crops and soil, and kills fish. Control: use cleaner fuels such as CNG, install scrubbers and catalytic converters, plant trees, use public transport, and avoid CFC products.
Normal rain has pH 5.6 and acid rain pH 4. How many times more acidic is the latter?
Each pH unit is a factor of 10: 10^(5.6 − 4) = about 40 times.
Why do marble monuments erode in polluted cities?
Acid rain reacts with calcium carbonate, dissolving it.
Name two ways to reduce vehicle pollution.
Using CNG and catalytic converters; using public transport.
1. Define a pollutant.
2. Name two gases responsible for acid rain.
3. What is global warming?
4. Name the chemicals that damage the ozone layer.
5. What is the pH of acid rain?
6. How does carbon monoxide form?
7. Give two effects of acid rain.
8. Write one measure to control air pollution.
9. If CO₂ rises 10% from 420 ppm, what is the new value?
10. Which layer absorbs ultraviolet rays?