Air District Operations

The Air District is taking steps to ensure Bay Area air quality and public health are protected while the shelter-in-place orders are in effect. Permits for businesses adjusting operations to aid in the public health response will also be expedited. Read more... | en Español

Air Quality Advisory

Smoke from wildfires may slightly impact local air quality and cause hazy skies. There is no Spare the Air Alert in effect on Friday and air quality is not expected to be unhealthy. See our hourly air quality data for the most up-to-date information, as well as Press Releases@AirDistrict, and our Wildfire Safety Tips web page.  Sign up for Bay Area Air Alerts.  en Español

Carbon-14 Analysis

Learn about the Air District's special purpose wood smoke monitoring project.

Residential wood burning contributes to fine particulate matter (PM) in the air. Currently, there are no methods to directly measure ambient PM from wood smoke, though the Air District employs several methods to estimate the contribution of wood smoke to PM concentrations. One of the most accurate estimate techniques is to utilize collected PM samples, which contain particles from all sources, during winter months (November 15 – February 15) and then analyzes them for carbon-14.

Carbon-14 is a radioactive isotope of carbon continually created in the atmosphere by cosmic rays. It has a half-life of 5,730 years. Trees and other carbon-containing objects that are exposed to the atmosphere contain trace amounts of this isotope. On the other hand, fossil fuels (another major source of particulate matter) contain essentially no carbon-14. This is because they have been in the ground for millions of years and their carbon-14 has decayed.

Carbon-14 analysis allows the Air District to estimate the proportion of ambient particulate matter that is due to wood smoke and the Air District has been using this technique over the years to determine contributions and changes in the amount of carbon-14 in Bay Area air.

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Meteorology & Measurements
Air Monitoring


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Spare the Air Status
No Wood Burning
Spare the Air Status
  • Friday,

    No Spare the Air Alert in Effect

  • Saturday,

    Spare the Air Alert in Effect

Last Updated: 9/8/2015