September 25, 2017 – During fire season, you often can see and smell smoke, and know right away that air quality is not great.  Another piece to the air quality puzzle is ozone.  The ozone layer up in the stratosphere is good, protecting us from the sun.  However, the ozone layer that we breathe can be harmful at concentrations as low as 70 parts per billion, which western Nevada County often experiences during the warmer months.

Ozone is formed by numerous chemical reactions involving sunlight, warmth, volatile compounds (mainly from vehicles, industrial processes and vegetation) and nitrogen oxides (mainly from vehicles, power generation and wildfires).  Most of Nevada County’s ozone comes from the Sacramento region, and concentrations are usually highest in the afternoon and evening when traffic is most dense.

High ozone levels can cause burning eyes, a sore throat, chest pain, coughing, headaches and other symptoms.  Some individuals are especially sensitive to ozone, including children, seniors, people with cardiac or respiratory conditions, and people breathing hard outdoors.

Unlike smoke, it can be hard to tell if ozone concentrations are high just by stepping outside, and it usually takes a few minutes to hours of exposure before ozone’s health effects are felt.  So, while the air may “look good,” before you plan strenuous work, play outdoors, and for the sake of your overall health, it is wise to check or for the most recent monitored and forecasted concentrations.