Three large wildfires, the Mission Fire in Madera County, the Pier Fire in Tulare County, and Railroad Fire in Madera/Mariposa counties, have prompted local air officials to extend the current health cautionary statement through the week. Currently smoke impacts are concentrated in the mountain and foothill areas of the air basin, but impacts on the Valley floor are possible until the fires are extinguished.

Overnight and early morning downslope flow may cause smoke to drift toward the San Joaquin Valley. While air quality impacts are forecast to be not as severe as over this past weekend, certain foothill and mountain areas may see unhealthy air quality with isolated pockets of smoke reaching the Valley floor.

The San Joaquin Valley Air Pollution Control District’s Real-time Air Advisory Network (RAAN) monitors are designed to detect the fine particulates (called PM2.5 which are microscopic in size and not visible to the human eye) that exist in wildfire smoke. Ash particles are much larger in size and will not be detected by the monitors. Therefore an area may be experiencing ash impacts from these wildfires while the PM monitor reflects a moderate reading. If you can see or smell smoke or ash it is an indication that you should be treating air quality conditions as “Unhealthy” (RAAN Level 4 or higher) and remain indoors.

Residents can check the District’s wildfire page at www.valleyair.org/wildfires for information about any current wildfires and whether they are impacting the Valley. Residents can also check the nearest air monitor to their location to determine localized air-quality conditions. Visit the Real-time Air Advisory Network page on the District’s website to subscribe for free: www.valleyair.org/RAAN.