SACRAMENTO, Calif. — Unhealthy air is starting to build in the valley with very little wind to clear the skies.

The Sacramento Metropolitan Air Quality Management District has issued a Spare the Air Day for Tuesday for Sacramento, Yolo, Placer and El Dorado Counties. People who are sensitive to poor air quality may find it tough to be outside, especially in the afternoon.

The best way to help keep the air cleaner on Spare the Air Days is to limit driving and use of gas powered equipment.

Spare the Air Days help
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Spare the Air ozone season starts May 1 and will run through the end of October.

Weather patterns during this time period promote ozone pollution. The sun’s ultraviolet rays react with volatile organic compounds (VOC) and oxides of nitrogen (NOx) to form ground-level ozone. Sources of VOC and NOx are cars, trucks, buses, construction/agricultural equipment.

Spare the Air Season
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Ozone can become especially problematic during long stretches of hot summer weather with little wind. At this time, the sun’s ultraviolet rays are reaching their peak. The late afternoon is the time when air quality tends to be the worst.

The central valley is a breeding ground for poor air in the summer. Our typical summer pattern of high pressure allows air to stagnate for several days or weeks leading to decreasing air quality.

The Sacramento and San Joaquin Air Quality Management districts monitor this air quality. They first measure pollutants, usually ozone, in parts per billion. That number is then translated into an air quality number indicating the different levels of tolerance.

High levels of ground-level ozone can lead to health problems especially with the elderly, children and people who have compromised respiratory systems. Wheezing, coughing, fatigue, headache and nausea can all be side effects from poor air quality. 

Air quality typically improves by November because cooler weather systems move through Northern California.  The upper air movement and precipitation keep the pollutants from stagnating.

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