1. Biological Sources: mean animals or pets, especially cats and dogs.
2. Mold and Mildew
3. Gas-Burning Appliances: gas-burning furnaces, especially older models, can release harmful toxins.
4. Paints and Finishing Liquids: contain Volatile Organic Compounds, or VOCs, releasing the harmful chemicals as gases.
5. Home and Building Materials: largely by releasing harmful toxins from paints and sealers, but also by the very nature of the product itself.
6. Air Fresheners and Scented Candles: Air fresheners don’t actually freshen the air, they merely release scented gases and mist. Certain types of candles contain toxic chemicals such as toluene and benzene, which are released into the air when burned.
7. Household Cleaning Chemicals: also release harmful chemicals into the air.
8. Radon: Radon is a naturally-occurring radioactive gas that seeps from the ground.
9. Tobacco Smoke: In case you haven’t heard, cigarette smoke is bad for you! (Are you shocked?) Even in modern times, it’s important to remember that tobacco products should be smoked outside, because even well-ventilated indoor areas will collect the toxics and smells of cigarettes, cigars, and pipes.