Air pollution from fossil fuel combustion includes particulate matter less than 2.5 (PM2.5) or 10 (PM10) microns, nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), carbon monoxide (CO), traffic-related air pollution, polycyclic aromatic hydrocarbons (PAH), and ground-level ozone (formed through chemical reactions from precursors from fossil fuel burning and other sources that include nitrogen oxides [NOx] and volatile organic compounds [VOCs] in the presence of sunlight).