Air is crucial to life; we humans breathe in and out an average of 12 times per minute! And when we inhale, we breathe in everything that floats around in the air, including tiny particles we can’t see. When pollution is released into the air from sources including power plants, factories, and automobiles, we inhale that as well. Polluted air can cause a range of human health impacts from minor allergies to serious respiratory problems, so it is important to keep our air as clean as we can and to take steps to reduce our exposure risks.