Ventura County Air Quality

Air Quality Forecast and Agricultural Burn Status

Real-Time Monitoring Station Data



Ventura County’s air quality has improved significantly since the district was created in 1968 even though the population has doubled. The graphs below plot ozone and particulate matter data against the National Ambient Air Quality Standards (NAAQS). The Environmental Protection Agency (EPA) periodically reviews the standards and sometimes lowers them based on the most recent science and epidemiological studies.


Ventura County - Federal 8-Hour Ozone Data



Ventura Couny - Federal Annual PM 2.5 Data



Although ambient, or outdoor, air quality data indicates significant progress in ozone and particulate levels, the county still exceeds current state and federal standards for ozone and the state standard for larger particles (particulate matter with a diameter up to 10 micrometers, or PM 10). The table below shows our progress toward these standards.


Ozone Statistic


Emissions from motor vehicles and other mobile sources account for more than half of Ventura County's air pollution. Other pollution sources include business operations, household products and fires.

A combination of factors often keeps emissions in Ventura County’s atmosphere where they can negatively affect people’s health. Frequently, there is a layer of warm air that prevents cooler air below it from rising, acting as a “ceiling” that traps emissions close to the ground. Meanwhile, our mountain ranges act as “walls” that prevent pollutants from spreading out horizontally. In addition, early morning breezes typically push pollutants west toward the ocean, and afternoon currents push them back to the east, mixing new emissions with older ones and keeping them in the air for several days. Air pollutants may not originate from where they are measured and, in some cases, can be transported over long distances.

When these stagnant atmospheric conditions align with warm temperatures, typically from May through October, sunlight reacts with pollutants to form elevated concentrations of ground-level ozone, the principal component of smog.

The strong Santa Ana winds that Ventura County frequently experiences, along with wildfires sometimes fueled by them, also affect air quality. Strong winds stir up dust containing PM 10. Wildfires fill the air with smoke and ash containing fine particles (particulate matter with a diameter of 2.5 micrometers or less, or PM 2.5). Wildfires also create a complex mixture of gasses that can elevate concentrations transported long distances from the fire location.

High levels of ozone, PM 10 and PM 2.5 can all harm the lungs and heart. Children, older adults and people with heart disease or respiratory conditions can be affected by lower levels of these pollutants.

The EPA developed the Air Quality Index (AQI) to communicate safe and unsafe levels of pollutants. When AQI levels are above 100, air quality is unhealthy for sensitive groups. Above 150, it becomes unhealthy for all. Knowing the air quality in your area can help you better plan your activities. Residents can view real-time data on Ventura County air quality and forecasts on the AirNow website or app. AirNow uses hourly data from the district’s monitoring stations in El Rio, Ojai, Piru, Simi Valley and Thousand Oaks.