Bad air means bad sleep. It can reduce the quality of sleep but more dangerously, air pollution increases the risk of sleep-disordered breathing, a group of disorders including sleep apnea, in which breathing stops briefly during sleep. Up to 17' of U.S. adults have sleep-disordered breathing, according to Antonella Zanobetti, PhD, a senior research scientist at the Harvard School of Public Health.
If humidity is too low, skin gets dry and chapped and it can exacerbate psoriasis and quickly lead to respiratory disease. If humidity is too high mold can proliferate in your home.