Air Monitoring Data Guide

The Air Monitoring Data page provides both real-time and historical information on air quality and meteorological conditions derived from measurements at air quality monitoring stations around the Bay Area.

What Information is Available?

Choices for sorting the information on the Air Monitoring Data page are available on the left column of the page.


Click on the Daily, Monthly, or Yearly links to bring up tables summarizing data on a daily, monthly, or annual basis - with the current day, month, and year set as the default.  (Note the scroll bar at the bottom of each display that must be used to view the full set of data.)


Displays measurements from each of the 24 hours of the selected day, with columns numbered 1 to 24.


Displays summarized information for every day of the selected month, with columns numbered accordingly.


Displays summarized information for each month of the year, with columns numbered 1 to 12.

Historical Data

The default date for the Air Monitoring Data page is set at the current day, but clicking on the calendar icon brings up a calendar where you can select a date within the past few years, and view air quality or meteorological information for that day, month, or year, depending on the display you've chosen.


There are three options, depending on which data you’re interested in reviewing:

Air Quality Index

This is the default View choice.  Air quality measurements for various pollutants are translated into the U.S. EPA’s color-coded Air Quality Index, or AQI, scale.  Orange-colored numbers over 100 are generally considered to be above the federal standard for each pollutant.  

Air Quality Index readings are available for the following pollutants:  carbon monoxide, nitrogen dioxide, ozone, PM2.5, and sulfur dioxide.


Selecting Data in the View menu bar shows measurements of actual concentrations of various pollutants at our monitoring stations.  (This is the actual data that is converted to Air Quality Index readings in the Air Quality Index view.)

You can compare these measurements to the federal and state ambient air quality standards for each pollutant.


Selecting Meteorology in the View menu bar shows various weather-related measurements - such as temperature, precipitation, and wind speed - collected from the Air District's meteorological stations.


Items available in the Measurement drop-down menu vary depending on which View term you have selected:  

Air Quality Index readings are available for five pollutant categories: carbon monoxide, nitrogen dioxide, ozone, PM2.5, and sulfur dioxide.  Generally speaking, PM2.5 is the pollutant of greatest concern in the winter months, and ozone in the summer.

Data measurements are available for a more extensive group of 11 pollutant categories.

Meteorology readings are available for nine weather-related categories.


These are the air monitoring and meteorology stations in the Air District’s air monitoring network.

The Stations drop-down menu defaults to All Stations - which displays measurements from all stations that monitor for the items selected in the View and Measurement drop-downs. (Note that not all stations measure for every pollutant or meteorological condition.)

You can also use the drop-down menu to select individual stations if you wish to focus on measurements from that one particular location.

Spare the Air Status

Last Updated: 3/19/2021