Answer:
Poor ventilation, very high or low humidity, mold, cleaning supplies, pesticides and many more.
Step-by-step explanation:
Poor IAQ (indoor air quality) can be caused by many factors. Lack od outside air as well as poor quality air that is coming from outside of a room/building. Quality of air can be judged by temperature, humidity and pollution.
Air pollution can be caused by fuel-burning combustion appliances, tobacco products, building materials and furnishings, cleaning supplies.