Air Monitoring Data

1. Use the map to find which air monitoring station you are interested in.
2. Use the drop down menu to select the air monitoring station
3. Once an air monitoring station has been selected, the pollutant drop down menu will update the available pollutants
4. Select which pollutant you are interested in.
5. Select the date range you are interested in. Please note that you are limited to a six-month window. If interested in a longer time period, you will need to do multiple searches.

EPA has set health-based standards for ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), lead (Pb), and particulate matter (PM). Particulate Matter is classified into two categories: PM2.5, which are particles with diameters less than 2.5 micrometers and PM10, which are particles with diameters less than 10 micrometers.

Establishing air quality standards require extensive toxicological and epidemiological evidence/ studies. For most pollutants, the science connecting specific exposure levels to public health outcomes is still evolving.

Multiple datasets may appear for the same pollutant at a site for different reasons. A site may operate more than one instrument measuring the same pollutant, or the site may report the pollutant using different averaging times (such as 1‑hour, 8‑hour, or 24‑hour averages). Each instrument or averaging time produces a separate dataset.

Continuous monitors collect measurements throughout the day at short‑interval averages, such as 1‑hour values. Intermittent (media‑based) samplers collect pollutant material over a defined sampling period, and depending on the sampler type, they may produce 8‑hour, 24‑hour, or other fixed‑interval values. These different measurement approaches may result in multiple datasets for the same pollutant at the same monitoring site.

EPA requires all air monitoring instruments to record and report data in Local Standard Time, which in our area is Pacific Standard Time (PST) throughout the entire year. The instruments do not switch to daylight saving time, so no hours are skipped or repeated. This approach ensures that each hourly and daily value aligns with a consistent time standard defined by EPA.

Blank values appear when a data point does not meet our quality standards. Instruments may malfunction, lose power, fail a quality check, or record a measurement that is not reliable. In these situations, the data is removed so the information we provide meets our data quality and measurement quality objectives.