Contamination of air by unwanted substances is called ______.
When air is contaminated by ________ substances which have a ________ effect on both the ________ and ________, it is referred to as ________. (air pollution, harmful, living, unwanted, non-living, pollutants).
(a) Is Air said to be polluted when it is contaminated with unwanted or foreign substances?
(b) Mention one man-made activity that leads to air pollution.
The substances which contaminate air are called __________.