Answer:
The correct answer is - b. false.
Step-by-step explanation:
Air pollution refers to small harmful substances or particles that get into the air and cause harmful effects such as breathing difficulty and disease associated with breathing. These particles can be chemicals, gases, dust, or biological pathogens and allergens such as bacteria and fungal spores.
Air pollution can be indoor air pollution or outdoor pollution, biological pathogen and allergen present more in indoor setting or system but they do not contribute only to indoor air pollution but all.