Highest 1-Hour Average Concentration of Ozone
This indicator measures the highest one hour ozone (O3) concentration in the calendar year. Ozone is created through a photochemical reaction between atmospheric oxygen, hydrocarbons and/or carbon monoxide, oxides of nitrogen, and sunlight. At high concentrations at ground level in the lower atmosphere, O3 is an air pollutant that can harm the respiratory systems of people and animals and damage plant tissue. The primary sources of the precursor gases in the Tahoe Basin include on-road motor vehicles, residential fuel combustion, motorized watercraft, off-road equipment, solvent, and fuel evaporation, and off-road recreational vehicles. Ozone can also be transported into the Tahoe Basin from outside sources. Regional programs such as reducing automobile use through transit and bike paths and cleaner-burning wood stoves aim to reduce ozone levels. Ozone is currently monitored at five locations around the Tahoe Basin by TRPA and partners.
Status
The highest 1-hour ozone concentration in parts per million (ppm) measured at all monitoring sites in the Lake Tahoe Basin. The location of monitoring stations has changed over the years. Ozone is currently monitored in five locations.
Evaluation Map
A map displaying current air quality monitoring stations within the Tahoe Basin. Ozone is monitored at five of these stations.
2019 Evaluation
- Status
- At or Somewhat Better Than Target
- Trend
- Moderate Improvement
- Confidence
- High
Applicable Standard
AQ3: Maintain ozone concentrations at or below 0.08 parts per million averaged over 1 hour.
Key Points
- Ozone levels are overall low compared to more urbanized areas and have remained in attainment for more than a decade.
- Due to its high elevation and frequent clear skies in summer, ozone levels in the Tahoe Basin are naturally high compared to other locations with comparable pollutant emissions. In addition to car, truck, and boat exhaust from within Tahoe, added ozone may come from large urban centers to the west.
- Peak ozone levels have dropped substantially since monitoring began in the 1970’s but have remained mostly unchanged in recent years.
Delivering and Measuring Success
EIP Indicators
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Miles of Pedestrian and Bicycle Routes Improved or Constructed
Since 1997 EIP partners have collectively constructed or improved 193 miles of pedestrian and bicycle routes reducing the number of vehicle trips.
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Non-Compliant Wood Stoves Removed or Retrofitted
This EIP performance measure tracks removal of polluting wood stoves to reduce local air pollution for human and ecosystem health.
Example EIP Projects
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TART Transit Operations 2025
Projects like this that expand transit operations on the North Shore limit car exhaust in the Basin.
Monitoring Programs