Air and Combustion: Atmospheric pollution

4.0 Air and Combustion

4.6 Atmospheric pollution

Many substances are continuously released into the atmosphere by human activities. Most of these substances are harmful to humans, plants and animals and negatively affect climate. They are called pollutants.

Pollutants include sulphur (IV) oxide, nitrogen (IV) oxide, carbon (II) oxide, excess carbon (IV) oxide, soot and metal oxides (solid pollutants) from factories and car exhaust, among others. They cause acid rain and respiratory diseases, while carbon (IV) oxide causes global warming, melting of ice at the poles, rising sea level, and harmful climate change.

Pollution involving release of gaseous and solid matter into the air economictimes.indiatimes.com

Questions 4.6(a)

1. What is the main problem associated with sulphur (IV) oxide and nitrogen (IV) oxide pollution?
2. Marble stones and cement are basically carbonates of metals, mainly of calcium. Explain why buildings made of marble and cement are easily destroyed by the oxides named in Question 1.
3. How would you determine whether the rain in your area is acidic or not?
4. What is the difference between acid rain and acidic rain?

Answers to Questions 4.6(a)

How else can we know if air is polluted?

Some plants are sensitive to pollution and only grow in safe environments. Lichens, for example, are very sensitive to sulphur (IV) oxide pollution. Where they appear on trees, the environment is still safe.

Did you know? Lichens produce litmus, a substance used to test for acids and bases (Topic 5).

At home and our surroundings (environment)

Some of the causes of air pollution are incomplete burning of cooking fuels, decomposing wastes - especially those rich in proteins, poor sanitation and sometimes unattended decomposing bodies of dead animals. Products of decomposing wastes include biogas: mainly a mixture of methane and hydrogen sulphide, which burn with hot flames.

Climate action

Knowledge of Air and Combustion can be used to solve problems of pollution and climate change. For example:

1. We should plant many trees to use up (in photosynthesis) the excess carbon (IV) oxide produced during burning. This prevents rising sea level which would submerge the land.
2. Use more efficient burners which produce less pollutants.
3. Biogas should be trapped and burnt as fuel instead of allowing it to escape into the air where it causes global warming.
4. The fire place in a house should be provided with a chimney to suck out any polluting products of incomplete combustion, such as soot and carbon (II) oxide.

Project Questions 4.6(b)

1. Suggest a reason why
   1. respiratory health problems or allergies are more common during the flowering season of crops such as maize plants and mango trees.
   2. after rains that follow a long dry spell, air normally feels fresh.
2. 1. Identify causes of major air pollution problems in your environment.
   2. Describe what you would do to help solve the problems.
3. Search the Internet for biogas to see how wastes at home can be turned into useful products such as domestic fuel.