What could be considered a source of indoor air pollutants?

Cooking and heating appliances are significant sources of indoor air pollutants because they can release various substances into the air as they operate. For example, gas stoves can emit nitrogen dioxide (NO2), carbon monoxide (CO), and volatile organic compounds (VOCs). Similarly, heating appliances, especially those that are unvented or malfunctioning, can contribute to the accumulation of harmful pollutants such as particulate matter and other combustion by-products.

In contrast, fresh outdoor air typically helps to dilute indoor pollutants and improve air quality. Properly vented bathrooms are designed to remove excess moisture and pollutants, further contributing to healthier indoor air. Air conditioning units, when properly maintained, should not be sources of pollution; however, if they are under maintenance and not functioning optimally, they can temporarily contribute to poor air quality. Therefore, cooking and heating appliances are a primary concern for indoor air quality.