Calculating air pollution from wildfires and other events has become more complicated. That doesn’t mean it’s necessarily more accurate.

As the Los Angeles wildfires continue, there are several sites and apps for checking air quality information in your area.

Depending on the fire, the smoke can be made up of various substances, including carbon dioxide, carbon monoxide, water vapor, particulate matter, organic chemicals, nitrogen oxides, and more. Exposure to smoke can cause a range of health effects, from eye and lung irritation to asthma and premature death.

With another surge of fierce Santa Ana winds, residents were asked to remain vigilant. An Air Quality Alert has been extended for many portions of LA County through Wednesday evening.