We received email today from the SJ Valley Air Pollution Control District with an updated warning on the Rough fire’s impact on valley air quality

The Valley Air District would like to warn schools in the communities of Madera, Fresno and Tulare County regarding specific impacts we’re seeing today from the Rough Fire in the Sierra Nevada:

Many areas are experiencing a cloud of visible ash falling from the sky. Please note that our RAAN monitors are designed to detect the fine particulates (called PM 2.5 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 our monitors. Therefore your area may be covered in ash, while our PM monitor reflects a moderate reading. If you can smell smoke and see ash, that is an indication that you should be treating air quality conditions as a Level 4 or higher.

A health caution is still in place for the entire San Joaquin Valley. We urge schools in areas impacted by fire smoke or ash to keep students inside. The news release is available here: http://www.valleyair.org/recent_news/Media_releases/2015/PR-health-caution-Rough-Fire-090815.pdf

Additionally, the Valley is still experiencing an Air Alert based on rising ozone levels. The RAAN monitors will effectively demonstrate ozone levels and should be referenced this afternoon during the hottest part of the day. The Air Alert news release is available here: http://www.valleyair.org/recent_news/Media_releases/2015/PR-Air-Alert-9-9-15.pdf