Vital Signs: Ozone Concentrations – by sensor (updated June 2017)

VITAL SIGNS INDICATOR Ozone Concentrations (EN2) FULL MEASURE NAME Ozone concentrations (O3) LAST UPDATED June 2017 DESCRIPTION Ozone concentrations refer to the quantity of ozone (O3) molecules in the air we breathe. In the Bay Area, ozone is measured by over a dozen monitoring stations that record hourly concentrations used to determine compliance with national standards. These hourly data are used to calculate eight-hour peak ozone levels for the fourth-worst day of the year, the most common indicator of ozone performance. This dataset includes regional and sensor-specific concentrations, as well as metropolitan area data. DATA SOURCE Bay Area Air Quality Management District 1970-2016 Air Quality Sensor Data http://www.baaqmd.gov/about-air-quality/air-quality-summaries CONTACT INFORMATION [e-mail] METHODOLOGY NOTES (across all datasets for this indicator) Data is collected at specific sensor sites operated by the Air District that capture the concentration of ozone in the air; sensor locations may change over the years and thus only minor relocations are shown as the same station in this analysis (e.g., sensor moved across the street from its prior location). Data are used to calculate the 8-hour peak concentration for ozone. The fourth-highest day of the year is identified and then reported as a three-year rolling average to minimize noise associated with any given year. These averaged are compared to the national air quality standard to determine compliance. The worst location site may shift from year to year depending on which sensor location had the highest levels of ozone over that particular time period.