Answer the following question given this paragraph: One source of indoor air pollution is radon gas. Radon is a radioactive gas that may seep into buildings from rocks underground. Exposure to radon gas may cause lung cancer. Another potential poison in indoor air is carbon monoxide. It may be released by faulty or poorly vented furnaces or other fuel-burning appliances. Indoor furniture, carpets, and paints may release toxic compounds into the air as well. Other possible sources of indoor air pollution include dust, mold, and pet dander. Q: Carbon monoxide, radon gas, dust and pet dander are sources of what kind of pollution? Choices: - noise pollution - light pollution - sound pollution - indoor air pollution A:
A:
indoor air pollution