A brief external-facing summary: As a result of anthropogenic climate change, an alteration in the air mixture has occurred over time. These changes have increased human exposures to respiratory irritants such as ground-level ozone, volatile organic compounds, nitrogen dioxide, sulfur dioxide, carbon monoxide, and polycyclic aromatic hydrocarbons. Regarding aeroallergens, studies have shown that elevated temperatures and increased carbon dioxide levels have produced prolonged and more robust pollen seasons for most taxa studied.