"Vanishing Greenery; A Growing Urban Crisis" In most of our cities, rapid urbanisation has led to a significant decrease in greenery over the past two decades. As the population increased, the demand for housing, roads and commercial buildings grew, leading to clearing of parks, gardens and natural resources. This has contributed to several problems.
How do green plants contribute to improving the air quality?
Topic: Plants and air quality
Answer
Green plants ABSORB CARBON DIOXIDE and RELEASE OXYGEN during photosynthesis, and their leaves TRAP DUST and other particulate pollutants, so the air is both cleaner and richer in oxygen.
Give BOTH mechanisms — the gaseous exchange and the physical trapping of dust. They are different kinds of benefit and together they make a complete answer.
This is a question where the PHOTOSYNTHESIS chapter answers an ENVIRONMENT question, and examiners like such links. The equation from Question 7(i) of this same paper is the justification: carbon dioxide in, oxygen out.
A third point if you have room: plants also absorb some gaseous pollutants such as sulphur dioxide and nitrogen oxides, and certain species are used as indicators of pollution — lichens die where the air is badly polluted, which is why their presence signals clean air.