Beware of unhealthy air following July 4 fireworks

Ventura County Air Pollution Control District has recorded annual spikes

(VENTURA, Calif. — June 18, 2024) The Ventura County Air Pollution Control District is warning residents that dangerous levels of very small particles can be caused by Fourth of July fireworks.

Historic patterns recorded by the district indicate that areas close to heavy fireworks use experience unhealthy air pollution levels. In 2023, the levels of fine particulate matter recorded for several hours on the night of July 4 in Simi Valley would be considered unhealthy for everyone if maintained for a 24-hour period, according to the Air Quality Index. The district monitor in Simi Valley is located two blocks east of the 2023 fireworks display at Rancho Santa Susana Community Park.

Also in 2023, a monitor in Piru, which is near Fillmore where a professional show was held and personal use of “Safe and Sane” fireworks is allowed, indicated the level of fine particles came close to the unhealthy level for sensitive groups. In 2021, the Thousand Oaks monitor recorded similar readings on the morning of July 5.

Fireworks emit high levels of fine particulate matter including soot and ash that can cause serious health effects. Toxic metals like strontium and barium produce the vibrant colors of fireworks. Illegal fireworks are known to contain additional toxic metals such as lead.

Particulate matter with a diameter of 2.5 micrometers or less, or PM2.5, can invade the bloodstream, get deep into the lungs and increase the risk of heart attack and stroke. It can irritate throats, lungs and sinuses and cause headaches, fatigue, coughing, wheezing, shortness of breath, asthma attacks and dry, watery eyes. Children, older adults and people with existing respiratory conditions are the most at risk.

When air quality reaches an unhealthy level, you should:


  • Stay indoors as much as possible, preferably in a “clean room” with an indoor air filtration device where you can avoid cooking or burning candles.
  • Close all windows and doors that lead outside unless it is extremely hot.
  • Operate home and car air conditioners in recycle or recirculation mode. Close the fresh air intake and replace dirty filters.
  • Avoid strenuous outdoor activity.
  • Consider wearing a properly fitted N95 mask when outside if you are sensitive to air pollution.


Levels of smoke and particles and the areas affected depend on weather conditions. For real-time data on air quality, check the AirNow NowCast AQI at or AirNow uses hourly data from the district’s five monitoring stations to provide air quality information.