Advisory warns of high ozone level |

Advisory warns of high ozone level

Increasing ozone levels, hot weather and a strong inversion layer has prompted an air quality advisory for people sensitive to respiratory conditions today – an ongoing problem that is concerning more and more residents.

Prevailing winds from the Sacramento Valley are expected to bring the city’s smog and ozone to western Nevada County as the day progresses, according to the Northern Sierra Air Quality Management District.

“The hotter it is, the more likely ozone is to form,” said Sam Longmire, air pollution control specialist for the air quality district.

Experts expect the inversion to begin breaking up later today and air quality to drop back into the acceptable range by this weekend, Longmire said.

Sensitive people include the elderly, children, asthmatics, adults with pre-existing heart and lung disease, pregnant women and people who exercise outdoors.

Ongoing problems caused by Central Valley smog blown up the hill have pushed the rate of asthma among county children to more than 17 percent – higher than the statewide average.

The nonprofit Save the Air in Nevada County is raising money for portable ozone monitors to track the pollutant, and members plan to take a clean-air resolution to the Grass Valley City Council on July 31.

So far this season, ozone levels in the county have violated federal standards for sensitive groups on three days in May and one in June, Longmire said. The standards are collected using an eight-hour average.

Ozone linked

to nausea, headache

Air quality is considered unhealthy for sensitive groups when it climbs above .085 parts per million or above an Air Quality Index measurement of 100. Air quality becomes unhealthy for everyone when measurements climb above 150 on the index.

When experts announced the air quality advisory early Thursday, they estimated the index would pass 100, Longmire said. Ozone levels usually rise to unsafe levels after 4 p.m., when winds push pollution into the foothills, he added.

Exposure to unhealthy ozone concentrations can result in chest pain, coughing, nausea, shortness of breath, throat irritation, headaches, congestion and chest discomfort.

“Quite a few people feel like they’re in a bad mood,” Longmire said.

Sensitive individuals are advised to avoid prolonged outdoor exertion during the late afternoon and evening, when ozone levels typically reach the highest levels. Ozone levels drop between 7 a.m. and noon.

Ground-level ozone happens when nitrogen oxides, often called “nox,” and organic gases, emitted from vehicles, power plants and other gas-powered equipment, react with sunlight.

For current ozone conditions visit


To contact Staff Writer Laura Brown, e-mail or call 477-4231.

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