In addition to the triple-digit temperatures expected this week, Southern California residents face another environmental danger: air pollution.

Through Wednesay, the excessive heat — expected to be over 100 degrees in Los Angeles County and up to 112 degrees inland — will increase “the likelihood of poor air quality in many areas,” the South Coast Air Quality Management District said in a news release.

Ground-level ozone or smog, the “predominant summertime pollutant,” is expected to reach unhealthy levels for sensitive groups (such as children, older adults and people with heart or lung disease) in some areas, and the San Bernardino Mountains and San Bernardino Valley are expected to be “even worse,” with very unhealthy levels possible during the afternoon, the AQMD said.

“Elevated temperatures increase emissions of chemicals leading to ozone formation and enhance ozone formation rates. This long duration and intense heat wave will likely cause unusually high and persistent levels of ozone pollution,” the release added.

Ozone pollution can lead to health issues like asthma attacks, trouble breathing and lung damage, and it can increase the risk of premature death, the AQMD said.

“Everyone is susceptible to the harmful effects of ozone … Breathing high levels of ozone can lead to some pretty bad health effects, so you want to protect your health,” said AQMD spokesperson Scott Epstein.

Air quality could be dangerous in the below areas.

• Los Angeles County
  • Central Los Angeles
  • Southeast L.A. County
  • West San Fernando Valley
  • East San Fernando Valley
  • West San Gabriel Valley
  • East San Gabriel Valley
  • Pomona-Walnut Valley
  • South San Gabriel Valley
  • South Central Los Angeles County
  • Santa Clarita Valley
  • San Gabriel Mountains
• Orange County
  • Northern Orange County
  • Central Orange County
  • Saddleback Valley
• Riverside County
  • Corona-Norco
  • Metropolitan Riverside County
  • Perris Valley
  • Lake Elsinore
  • Temecula Valley
  • Anza Valley
• San Bernardino County
  • Northwest San Bernardino Valley
  • Southwest San Bernardino Valley
  • Central San Bernardino Valley
  • East San Bernardino Valley
  • West San Bernardino Mountains
  • Central San Bernardino Mountains
  • East San Bernardino Mountains

For more information, visit the AQMD’s website, or check out the Air Quality Index map.