Current Air Quality and Smoke Monitoring
General air quality information:
Yosemite National Park monitors smoke/fine particles and ozone as part of a nationwide effort to protect air quality and public health. Current nationwide conditions are mapped below:
View of the Merced River Canyon, looking west from Yosemite Turtleback Dome, at 5,266 feet (1605 m) above sea level, toward the Central Valley. Direct links to other Yosemite webcams are below:
Yosemite Air Quality Monitoring:
The chart below plots both the 1-hour and running 24-hour average PM2.5 concentration, but only the 24-hour average should be used to compare with the standard. The standard is exceeded when the 24-hour concentrations go above 35 micrograms per cubic meter, as denoted by the line with the label NAT'L AMBIENT AIR QUALITY STANDARD. The background of the chart is color coded and relates to the EPA National Ambient Air Quality Standard for particulate matter, which is designed to protect human health.
A note on campfires and campgrounds: Some Yosemite campgrounds have many campsites and campfires. Emissions from many simultaneous campfires can degrade air quality on a local scale. This is especially true in the nighttime and early morning hours, when inversions trap and concentrate fine particles from those campfires near the ground, creating local conditions that are potentially unhealthy for sensitive individuals.
Ozone and human health in Yosemite:
Where in Yosemite is ozone usually a concern?
In more sheltered areas like the Yosemite Valley and remote, high elevations areas like Tuolumne Meadows, ozone is usually much lower, rarely unhealthy even on most polluted of days.
When is ozone usually a human health concern in Yosemite?
Yosemite Ozone Monitoring:
Yosemite has been monitoring ozone at three sites for several years now: Seasonally at Yosemite Valley Schoolyard and Glacier Point, and year-round at Turtleback Dome.
The charts below plots both the 1-hour and running 8-hour average ozone concentration, but only the 8-hour average should be used to compare with the standard. The standard is exceeded when the 8-hour concentrations reach or go above 75 parts per billion, as denoted by the line with the label NAT'L AMBIENT AIR QUALITY STANDARD. The background of the chart is color coded and relates to the EPA National Ambient Air Quality Standard for ozone, which is designed to protect human health.
Ozone at Turtleback Dome west of the Yosemite Valley, overlooking the Merced River Canyon at 5,266 feet (1605 m):
Ozone at Yosemite Valley Schoolyard, near Yosemite Falls, at 3977 ft (1212 m) is no longer available in real time, but archived data can be found at: http://www.nature.nps.gov/air/monitoring/network.cfm
Online Tools to Locate a Fire Nearby