Many Piedmonters avoid air conditioning and follow the advice of the State and PG&E to open windows overnight to cool their homes.  This natural cooling method has worked for months, but on the morning of August 19, they found the air flow had admitted unwanted pollution into their homes and scurried to close their houses against the dangerous smoke.

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Local Piedmont indoor measurements at 7am on Wednesday were between 099 & 102 μg/m3 particulates less than 2.5 microns.  (Normally, it is 000 to 005.)

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EPA established Particulate Matter (PM) standards that specifically addressed particles smaller than 2.5 microns (PM_2.5). The annual standard was set 2012 at 12 micrograms per cubic meter (μg/m³), based on the 3-year average of annual mean PM_2.5 concentrations.

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The size of particles is directly linked to their potential for causing health problems. Fine particles (PM_2.5) pose the greatest health risk. These fine particles can get deep into lungs and some may even get into the bloodstream. Exposure to these particles can affect a person’s lungs and cardiovascular effects including cardiac arrhythmias. Children, people with asthma, and older adults are the most likely to adverse health effects.  The California Air Resources Board reported: “children and infants are susceptible to harm from inhaling pollutants such as PM because they inhale more air per pound of body weight than do adults – they breathe faster, spend more time outdoors and have smaller body sizes. In addition, children’s immature immune systems may cause them to be more susceptible to PM than healthy adults.”

Coarse particles (PM_10-2.5) are of less concern, although they can irritate a person’s eyes, nose, and throat.  Air purifiers with HEPA filters capture coarse particles (but may not reduce the most dangerous smaller particles) and can relieve obvious eye and throat irritation.

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On Wednesday, August 19 at 8:30 pm the 10 minute average PM_2.5 at EPA’s central Piedmont monitor was 154.