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In recent years the Air District has begun monitoring and forecasting for PM2.5, as well as introducing a dioxin monitoring network measuring levels of that highly toxic pollutant.

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Monitoring Site

Cupertino Location


Air Monitoring Station at Monta Vista Park in Cupertino, CA

Monitoring Instruments 

monitoring instruments

Special Purpose Monitoring in Cupertino

On September 1, 2010, the Air District began a special air monitoring study in Cupertino, California. The purpose of the study is to determine if Cupertino residents are exposed to elevated pollution levels that might not be captured at other air monitoring stations in the Bay Area.

Cupertino residents had been concerned that the Lehigh Cement Plant and its associated diesel truck traffic could have significant air quality impacts on nearby neighborhoods. Consequently, the study measures pollutants in ambient air specific to those emissions from Lehigh and its associated truck traffic.

After collecting an entire year of data from September 2010 through August of 2011, Air District staff reviewed the data and developed a Summary and Analysis of Cupertino Monitoring Results – Revised Including 2012 Data

The Air District’s Cupertino air monitoring equipment is housed in a trailer at Monte Vista Park, in a residential area about one mile east of the Lehigh Cement Plant and two blocks south of Stevens Creek Blvd. Pollutants continuously measured include ozone, sulfur dioxide, particulate matter, nitrogen oxide, nitrogen dioxide, hydrocarbons, and carbon monoxide. Hourly averages for these pollutants can be viewed and compared with other locations on the Air District’s Real Time Air Quality Data web page.  Hourly winds and temperature are also measured in the park.

In addition, 24-hour samples of ambient air are collected every sixth day and analyzed for toxic gases and metals. The samples are collected in canisters and on filters for later analysis at the Air District and contract laboratories. Toxics and metals data are available for viewing. Further information about air toxics can be found at the California Office of Environmental Health Hazard Assessment (OEHHA) web site. For comparison, toxics data summaries for other monitoring sites throughout California can be found at the California Air Resources Board (CARB) web site. It is important to note the averaging and reporting time frames on these websites to ensure that the data are comparable.

In addition to the special Cupertino monitoring site, the Air District operates 24 permanent air monitoring stations within the Bay Area. The closest permanent monitoring station to Cupertino is 9.8 miles east in downtown San Jose. Air quality measurements at the San Jose station are comparable to measurements taken at other stations around the Bay Area: most pollutants are well below state or federal ambient air quality standards, with the exception of ozone and fine particulates. Air quality measurements at the Cupertino station have also been well below state or federal ambient air quality standards, including measurements of ozone and fine particulates.

Table 1 below lists the pollutants measured at Cupertino and the sampling frequencies.

Table 1. Pollutants measured at Cupertino

Pollutant MeasuredSampling Frequency
Carbon Monoxide (CO)Continuously
Nitrogen Oxides (NOx)Continuously
Ozone (O3)Continuously
Sulfur Dioxide (SO2)Continuously
Fine Particulates (PM2.5)Continuously
Toxic Gasses and MetalsEvery 6 days
Last Updated: 7/15/2014