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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.
Last Updated: 3/24/2021