SONORA—The Ferguson and Donnell Fires continue to affect air quality in many areas of Tuolumne County. Smoke accumulation has rendered air quality unhealthy for sensitive groups in some areas and unhealthy to very unhealthy in other areas for everyone (see chart below).
The following information is provided to allow you to assess the air quality in your immediate vicinity and to provide guidance for those people who live in neighborhoods affected by poor air quality.
Because the Tuolumne County geography may entrap smoke in certain valleys and basins, the following visibility chart can be used to determine the air quality where you are. Visibility provides an excellent measure of air quality.
First identify on a map certain landmarks on the horizon. Then check to see at what distance the landmarks can no longer be seen. The distance of this landmark is the "visibility in miles."
Note that some areas are also affected by extreme heat and people who are not acclimated to the higher temperature, or are dehydrated, may experience additional stresses on their heart and lungs.