Indoor Air Quality

Indoor air can sometimes contain higher concentrations of particular pollutants than outdoor air: the EPA reports typical levels of some common organic compounds at 2–5 times higher indoors, with short-lived spikes possible during certain activities. But there is no universal rule that all indoor air is “30 times dirtier” or always contains more bacteria, dust, and allergens than the air in a particular city. Sources, ventilation, and outdoor air quality matter. [1–3]