Areas of Alpine, Borrego Springs and Warner Springs have the highest levels of ozone pollution in San Diego County, according to state data that indicates the level of air pollution in a given neighborhood.

Ozone is the main ingredient of smog, which makes it among the most widespread and significant air pollution health threats in California. Studies show it can cause lung irritation and inflammation, and even low levels of exposure can worsen existing chronic health conditions. It is created when pollutants from vehicles, factories and farm chemically react in the presence of sunlight.

Data from the California Environmental Protection Agency show the average daily maximum ozone concentration in central and northern Alpine is .057 parts per million, the highest in San Diego County.

Several areas of San Bernardino, including Highland, Loma Linda and Redlands, top the statewide list with an average daily maximum of .068.

Borrego Springs and Warner Springs sit at No. 2 in the county with .055 parts per million. The measurements reflect the average 8-hour maximum during 2012 and 2013.

CalEnviroScreen 3.0 incorporates ozone levels, as well as diesel emissions, groundwater quality, hazardous waste and pesticide levels, into one interactive tool that state officials say helps identify environmentally-disadvantaged communities.

The tool was created to prioritize funding for grants and other programs after Governor Jerry Brown passed legislation in 2012 that required 25 percent of cap-and-trade auction proceeds to go to projects located in communities particularly vulnerable to pollution and its effects.

According to state research, ozone levels are typically highest in the afternoon and on hot days. Children are the most sensitive to ozone exposure, but it can also affect the elderly and people who spend a lot of time outdoors.