The Tahoe Regional Planning Agency (TRPA) and its partners have monitored criteria pollutants, aerosol species concentrations, and meteorology since the late 1980’s to assess air quality and visibility in the Lake Tahoe Basin. Below are the air quality constituents currently monitored:

• Ozone (O3) - In the Earth's lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Ozone at ground level is a harmful air pollutant. It takes a long time to form and travels long distances from large metro areas to less populated areas such as the Tahoe Basin.
• Carbon Monoxide (CO) - CO is a very localized pollutant of concern that mostly comes from automobile exhaust. It is very harmful to human health at sufficiently high concentrations. Because it is a very localized pollutant, it generally only is of concern immediately adjacent to busy roadways or indoors.
• Oxides of Nitrogen (NOX) - NOX and NO2 is a pollutant that is mostly a concern in large metropolitan areas (over 1 million) and along freeways. It is created mostly through the burning of fossil fuels and automobiles and is mostly a concern due to its impacts on human health at sufficiently high concentrations. 
• Particulate Matter 2.5 (PM2.5) - PM2.5 in the Tahoe Basin mostly comes from the burning of solid fuels either through wildfires or woodstoves and campfires, as well as vehicle exhaust. It is a hazard to human health and is a major component to reduced visibility.
• Particulate Matter 10 (PM10) - PM10 in the Tahoe Basin mostly comes from dust created by snow removal operations, sanding operations, and cars crushing pavement and gravel, as well as smoke from wildfires and woodstoves. It is a hazard to human health.