There are two types of air quality that impact schools: indoor and outdoor. Indoor air quality (IAQ) is largely a function of the ventilation of the school and the chemicals introduced into the air. Though much attention has been paid to improving outdoor air quality, and rightly so, the EPA has found that IAQ can be much more toxic that outdoor air quality. Even students and teachers with no respiratory ailments can be adversely affected by poor IAQ, but those with asthma and allergies can be particularly miserable in schools with polluted air. Optimal learning environments are those where all the inhabitants can breathe easily, both indoors and out.