More air quality alerts have been issued in California this year than last year during the same period, according to data from the National Weather Service (NWS).

Although it is difficult to discern the exact number of air quality alerts issued in a state based on NWS regional boundaries, NWS data shows an upward trend in air quality alerts. air in California this year.

Last year, NWS offices in California issued about 60 air quality alerts through October 22, 2023. So far this year, about 100 alerts have been issued for the same areas. Most alerts are limited to the southern half of the state.

News week contacted the California Air Resources Board by email for comment.

Air quality alerts are most often issued in the summer because weather conditions can have a significant impact on ozone, and this summer has brought a wave of air quality alerts. air across the country.

The alerts, which NWS offices often issue on behalf of an air quality authority in the area, were triggered by weather conditions, wildfire smoke and other pollutants.

Often, air quality alerts are accompanied by a call to action for citizens in affected areas. Depending on the pollutant, residents were asked to carpool, avoid driving or refrain from using gas-powered equipment until air quality improves in order to limit their emissions . Some alerts also asked citizens to delay visits to gas stations until air quality improves.

“Different aspects of weather affect the amounts of ozone and particulate matter present in a specific area,” says an NWS website on the subject. “Sun, rain, higher temperatures, wind speed, air turbulence and mixing depth all affect pollutant concentrations.”

The website goes on to say that sunlight can “cause chemical reactions in certain pollutants, leading to the development of smog.” Warmer air can also increase these reactions. Rain, on the other hand, removes some pollution and can improve air quality.

“Wind speed, air turbulence, and depth of mixing all affect how pollutants disperse or spread from an area,” the website states.

Wildfires are also more common in summer, contributing to poor air quality.

Other common causes of summer ozone include urban air pollution and human-caused emissions, Steven Brown, head of the tropospheric chemistry program at the National Oceanic and Atmospheric Chemical Sciences Laboratory, said previously. Administration. News week.

Exposure to ozone can lead to a host of health problems, such as aggravating lung disease. The NWS website lists a series of actions people can take to help reduce air pollution, such as reducing the use of fireplaces, driving less, refraining from lighting candles, and using less energy while alerts are in effect.

According to NWS data, the region with the most air quality alerts in 2024 and 2023 was in southern Arizona. Phoenix is ​​one of the most air-polluted U.S. cities, Cronkite News reported. Frequent sunny weather and high pressure in the region contribute to pollution.

The region with the second highest air quality alert this year was in north-central Colorado.