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Yosemite National Park
Current Air Quality and Smoke Monitoring
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This page displays the latest information and links from Yosemite's air quality and smoke monitoring network. Also, visit a general air quality webpage and general smoke page.
Air Quality Alerts: None at this time.
Air Quality Advisory: None at this time (See NPS advisories from a nationwide park list).
Air Quality Discussion: The Big Meadow Fire is 100% contained, and air quality has returned to baselines. Any time unhealthy levels of smoke occur, people can protect themselves by staying indoors or moving away from impacted areas. It is also a good idea to protect indoor air quality by closing all doors and windows and, if possible, setting ventilation systems to re-circulate air. Anyone with respiratory ailments, young children and older adults should limit their exposure to smoky air by staying indoors, or temporarily seeking areas with cleaner air. See www.epa.gov/airnow for more information on these AQI guidelines and for more information on how to minimize exposure to wildland fire smoke.
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Smoke Observations for the Central Sierra Nevada (Sept. 10, 2009, updated as needed): Transported smoke from large fires can impact areas hundreds of miles away, and satellite products like this help us see potential sources of our smoke. Low density smoke from the Big Meadow fire (now 100% contained) is now so localized that it is not detectable by satellite, while smoke from the Station Fire in Southern is now only barely detectable. Further updates to the current image (right) will be updated as needed. The green areas indicate areas of low-density smoke; yellow and red areas are relatively denser. These smoke observations are based on a satellite-derived aerosol optical depth product, and smoke density does not necessarily equate directly to smoke concentrations or health impacts at the surface. Data courtesy of the NOAA Hazard Mapping System. There is an online (ArcIMS) mapping tool on this site that yields the most current version of the image to the right.
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 What's This View? Enlarge this current view from Yosemite's Turtleback Dome, at 5,266 feet in elevation, looking west over the Merced River Canyon toward the Central Valley. Ozone and meteorological data (temperature, humidity, and winds, for example) are also posted at this link. For additional Yosemite webcams, see below.
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Fine Particles and Smoke: Mountain campgrounds and other low-lying, flat areas can have significant campfire activity. Nighttime and early morning inversions can trap and concentrate fine particles from those campfires near the ground, creating conditions that are potentially unhealthy for individuals with respiratory and/or pulmonary ailments. Locally heavy smoke might also be found in the vicinity of prescribed or wildland fires that occur every year in the park. Particles are usually at their highest concentration late at night through early morning. Yosemite's fire management program works to minimize such impacts while protecting our fragile fire ecology. You might also want to check out Yosemite's fire history map to see where fires (and their smoke) commonly occur in Yosemite.
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| Click for current particulate matter levels. |
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View fine particle levels from the Yosemite Valley Visitor's Center. Graph displays data for the past several days.
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Mobile Smoke Monitoring: You can see fine particle/smoke levels in near real-time on the Interagency Real Time Smoke Monitoring web site, which includes both of Yosemite's mobile smoke monitors. Once on the page that lists the mobile monitors, look at the far right column to link to both of the park's monitors. Note that the graphs that appear only present the past 24 hours of data. To access data more than 24 hours old, click on the “data details” button to the left of the graph. A screen will appear that allows the user to enter any date in the field to see what measurements, if any, were produced on a given date or range of dates. The following intruments are monitoring air quality in and around Yosemite:
- NPS YOS1001 Bam: located in Yosemite Valley about a mile away from the Visitors Center at the Lower Rivers amphitheater. This site best captures the combined impact of both campfires and more large-scale smoke impacts.
- NPS YOS1000 Ebam: located in El Portal, on the west edge of the Park along Highway 140 in the Merced River Canyon
- NPS YOS1001 Bam: located in Foresta Fire House, near the Big Meadow fire.
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Ozone: Because ozone pollution near the ground is usually only a concern on hot, sunny days, the ozone "season" runs May through September. In the Yosemite frontcountry near ridgetops (like Turtleback Dome), ozone is often (30-40 days per year) found at levels unhealthy for sensitive individuals (asthmatics or others with respiratory ailments). In sheltered areas like the Yosemite Valley Schoolyard and remote, high elevations areas like Tuolumne Meadows, ozone is usually much lower, rarely unhealthy even on most polluted of days.
Highest levels of ozone on a given day usually occur in late afternoon and evening. If you have a respiratory condition, such as asthma, consult a doctor before exercising strenuously in areas where and during late afternoon periods when high ozone might occur. (See current ozone data and the ozone forecast below.)
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Ozone and Smoke Forecast (Experimental): View a 48-hour ozone prediction from NOAA's National Weather Service. Specifically for:
Note that these products are experimental and can be unreliable.
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General Air and Weather Information
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| NASA | | Click to see today's NASA satellite imagery of the Yosemite area. |
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View Online Tools to Locate a Fire Nearby
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Did You Know?
In March 1987, the largest historical rockfall in Yosemite National Park deposited an estimated 1.5 million tons of debris at the base of Three Brothers, closing Northside Drive for several months.
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Last Updated: October 21, 2009 at 14:38 EST |
