The Effects of Wood Smoke on Health - Why should We Care?
The biggest source of air pollution during the winter in the San Francisco Bay Area is wood burning. Burning wood along with other solid fuels like pellets can produce a number of pollutants, but the pollutant that is mainly targeted by winter Spare the Air Days is Particulate Matter.
Types of Particulate Matter
Particulate Matter is classified into two different groups based on size: PM10 and PM2.5. Wood smoke can contain both types of particles. PM10 particles are 10 millionths of a meter (10 microns) or less in diameter, while PM2.5 particles measure 2.5 microns or less. While both types of particles can cause health problems when inhaled by humans, PM2.5 particles are more concerning because they can penetrate deeper into our lungs due to their small size. These particles cause the lungs to work less efficiently by blocking the passageways that air must pass through to reach the bloodstream. This blocking can cause shortness of breath or even serious respiratory health problems like asthma. In addition, if harmful chemicals are present in the fire, those chemicals can become particulate matter as well and further complicate the health of those that breath the particles in. People who are very old or young are generally the most affected by particulate matter in the air (along with other pollution), while those with preexisting respiratory problems may see those problems aggravated by particles in the air.
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Particulate Matter Size Comparison |
How Do Spare the Air Days Help?
Spare the Air Days are called when the BAAQMD predicts a day of bad air quality. In the winter, this bad air quality can be caused by a temperature inversion, as discussed in this site under "The Science Behind Spare the Air > Temperature Inversions." Since the inversion causes the air surrounding us in the Bay Area to be stagnant, any extra pollution released into the environment by burning solid fuels dramatically worsens the already bad air quality for that day. This philosophy of preventing the air quality from becoming too bad on any one day is the driving force behind the implementation of individual Spare the Air Days.