As part of its Air Quality Monitoring Project, San Juan County has installed a PM2.5 monitor on the Orcas Senior Center building.

What are PM2.5? PM2.5, which stands for “Particulate Matter 2.5, are microscopic particles that are only a tiny percentage of the diameter of a human hair in size (2.5 micrometers or smaller, to be exact). Their microscopic size allows them to bypass the protective areas of the nose and throat and penetrate deep into the lungs, potentially causing health problems. On Orcas Island, the most common sources of PM2.5 are motor vehicles, residential wood burning, and seasonal forest fires.

The box below shows up-to-date readings from the PM2.5 air quality monitor installed at the Orcas Senior Center. Any number less than 50 is considered to be generally safe. Click on the “Purple Air Map” text at the bottom to get even more information from the sensor and to see readings in other locations.

For public health guidance from San Juan County Health & Human Services for PM2.5 concentrations, go here.