As wildfires continue to burn in San Diego County, we will be providing up-to-date information and measurements of the air quality in our region. Check back periodically for Air Quality update discussions. We will be expanding our coverage as time goes on and new pieces of information become available.
If you find yourself in a region affected by wildfire smoke:
- Your nose and eyes are very good sensors for smoke pollution. If you can smell smoke and visibility at ground level is about 5 miles or less, it's time to start thinking about protecting yourself.
- If possible, move to a location that is less impacted by smoke. While you are within an area affected by smoke that's at ground level, use a filter mask or wet cloth over your nose and mouth to help limit inhalation of smoke particles.
- Those with athsma or other respiratory conditions, the elderly, and young children can be especially sensitive to particulate (smoke) pollution.
[Image at right: Wildfire plumes from San Diego and Baja on May 14, 2014. MODIS/Aqua, LANCE; NASA/GSFC]
For the three areas measuring particulate matter, there is a decrease in particulate matter concentration, indicating that air quality levels are returning to normal. The fires are over 50% contained, which is consistent with the improvement in air quality. This morning's sounding (top right above) shows a low level inversion over San Diego, which is typical for late spring and onshore flow conditions. The inversion acts to create a shallow atmospheric boundary layer, which will tend to trap smoke and air pollutants near the surface, suggesting that areas at lower elevation will be susceptible to smoke. Over time, the air quality in these areas will improve as the fires become more contained, albeit more slowly than if winds were strong or in the presence of a deeper boundary layer.
Because air quality levels are returning to normal, this will be our last blog post. We will continue to keep you updated as any future fires occur, as we expect the fire season to be active throughout the summer and the early fall. Persistent drought with intermittent heat, and dry conditions are expected, so check back periodically for updates on the air quality in San Diego County.
From AirNow.gov. Yellow indicates "Moderate" air quality conditions. Visibility is reduced and particularly sensitive individuals should take precautions.
Air Quality Discussion
Since containment on all fires in SD County is greater than 25%, with the weakest containment occurring in the open wildlands of Camp Pendleton, air quality in the majority of the San Diego region has been less directly impacted by wildfire smoke. A combination of relatively stagnant conditions and leftover emissions from the fires are causing moderate particulate matter pollution levels to persist in Southern California (see the map above, at right). The trend in particulate matter concentration shown on the left is still gradually increasing as of this morning. Lower-lying regions are more at risk of elevated pollution levels, as the haze layer that is blanketing much of San Diego (inland to Escondido and Alpine) tends to collect in basins between hills and mountains. Traveling to a high viewpoint, for instance, Mt. Soledad in La Jolla, or atop the Poway Grade, will allow for a clear visual picture of the ground-level haze layer.
While containment of the North County fires continues to improve, we have seen air quality in coastal southern San Diego County deteriorate. Onshore winds returned yesterday afternoon, which transported the remnant smoke plume back over land. Hazy conditions with elevated particulate matter will continue this afternoon, as weather models predict continued onshore winds in a "coastal eddy" type pattern near San Diego. This afternoon we will examine air quality conditions here on the UC San Diego campus, as we expect to see greater than normal carbon monoxide and smoke as the North County plumes continue to come onshore and affect Central and Southern San Diego county.
Image: MODIS Aqua (Natural Color), NASA/GSFC (May 15, 2014)
Air Quality Discussion
Air quality for Central and Southern San Diego Counties is beginning to be affected by the wildfires in North County. Much of the wildfire smoke at this time is localized to areas near to active burning zones, but around the region, we are starting to see more particles in the air at Air Quality monitoring stations throughout the county. The Camp Pendleton/Oceanside station (located near Oceanside Pier), is being heavily affected by the Las Pulgas and Tomahawk fires aboard Camp Pendleton. The Downtown and Escondido stations are likely affected by North County fires in addition to increasing particle concentrations in the air simply due to the weather conditions associated with the Santa Ana winds. In any case, both particulate matter and ozone levels are moderate to high today throughout the county.
We may see increasingly widespread air quality problems as the Santa Ana winds start to break and more typical winds from the west bring the wildfire smoke back onshore -- the smoke plumes can be seen over the ocean in the satellite image above -- as we saw in prior seasons with heavy wildfire activity (like 2003 or 2007).
Regions of North County from Carlsbad to the southern extent of Camp Pendleton, and eastward to Escondido should expect particulate matter in the air to be prevalent even after active flames are extinguished. Smoldering fires continue to produce smoke long after the flames have been put out, and the smoke can remain in the lower atmosphere for long periods of time. Stay tuned to our air quality updates, even after the fires are put out and the Santa Ana winds have died.