This document discusses the importance of air and outlines various factors that affect air quality. It notes that while air is composed primarily of nitrogen and oxygen, it also contains other gases and water vapor. It then explains that air purification removes gases, acids, dirt, germs and ozone from the air. The document also outlines some of the negative health effects of air pollution and notes that conditions like asthma and allergies can be exacerbated by pollution. It provides tips for improving indoor air quality and protecting oneself from pollution.