Community Air Quality Monitoring in Sacramento, CA

Air pollution can vary greatly from one area to another – even within the same community. To better understand air quality in Sacramento, a van equipped with research-grade air monitoring instruments was driven throughout the city from February to April 2023. This monitoring effort measured air quality information block-by-block to identify areas that are the most impacted.

Air pollution occurs when gases and particulates are released into the air from cars, trucks, factories, fires, and even dust. Breathing polluted air can cause serious health problems like asthma or heart disease and can cause coughing, eye irritation, headaches, and fatigue. These problems can be worse for children, pregnant women, adults 65 and older, and people with pre-existing health conditions. For more information on air quality and health, please visit  AirQuality.org .

The project was completed in three phases:

• Phase 1: The mobile monitoring van measured air pollution levels in nine Sacramento communities between February 16 and April 1, 2023. Data collection occurred during the daytime during both weekdays and weekends.
• Phase 2: The data were then analyzed to find areas with higher pollution levels, called pollution focus zones (PFZs).
• Phase 3: The van was parked at each PFZ to take extra measurements for one day at each location between March 24 to April 16, 2023.

Nine communities in Sacramento were selected for mobile monitoring using the EPA  EJScreen tool  and data from the Sac Metro Air District’s  Community Air Protection Program .

The van was driven through each neighborhood along six routes (image below) at different times of the day and week to measure air quality. Routes were chosen to prioritize side roads, to focus on neighborhoods and areas near schools, and ensure coverage of each community. The van was driven in a rotating order so that each community was measured multiple times throughout the day.

To ensure the data would be reliable, the Project Team used the U.S. EPA’s  Quality Assurance Handbook Volume II Appendix D  to guide the quality control process. Two quality control methods were used:

• Calibration – Adjusting the instruments to a known standard, using certified standards and instrument-specific protocols, before using them.
• Verification – Checking the instruments during the project by comparing them to a known standard (EPA certified gases) to make sure they were collecting reliable data.

The Project Team also followed important monitoring guidelines while using the van to collect air quality data. This includes driving slower than 25 mph when possible to lower the impact of the van’s movement from changing the makeup of the air, and staying two-to-three car-lengths behind other cars to stay safe and avoid direct tailpipe emissions from other vehicles.

Mobile monitoring data were summarized into air pollution maps that show average above background concentrations, also called local concentrations. Local concentrations are influenced by nearby pollution sources and can help identify specific air quality problems within communities. The image below shows an example on how local concentrations were determined. Total, regional concentrations are the combination of local and background concentrations.

The  FINAL REPORT  provides a detailed summary of the mobile monitoring data and analysis. Observations of the local concentrations from mobile monitoring data are summarized in the following table.

The following maps summarize the analysis results, where lighter colors (yellow) mean average pollution was similar to the community average, while darker colors (brown) show areas with higher average pollution. Interact with the maps by zooming in and out with the + and – buttons, and by clicking and dragging to see concentrations in specific areas. 

*Please note that mobile monitoring data cannot be directly compared to air quality health standards. Health standards require continuous data at a single location averaged over longer periods, such as over 24 hours or annually, while this effort only collected snapshot measurements averaged over 21 days. However, looking at the data in the context of health standards can still provide helpful insights.

Pollution focus zones (PFZs) are areas with higher pollution levels that were identified using advanced statistical analysis of the mobile monitoring results and selected for additional data collection. The mobile monitoring van was parked in each of the 10 identified PFZs to collect 6-12 hours of additional data. Hourly averaged measurements provide a snapshot of pollution levels over one day. These measurements represent the total, regional concentrations.

Although these results cannot be directly compared to air quality health standards, they can help identify potential areas of concern. PFZ monitoring results are summarized in the following tables.

Community monitoring allowed us to capture snapshots of the air pollution within nine Sacramento communities. Investigating local concentrations can help identify nearby sources of emissions and determine how much local levels are contributing to the total, regional concentrations. The following table highlights overall observations from the mobile monitoring and the PFZ monitoring parts of the project.

To access the full report, click on the following link:  FINAL REPORT .

• This mobile monitoring effort is one part of a larger, three-part project that also includes expanding the portable sensor network in Sacramento and creating a curriculum for students interested in air quality careers.
• This project also supports AB617 monitoring efforts to increase air monitoring in underserved communities.
• Data from this project, along with existing monitoring efforts within the region can be a resource for partner agencies and community organizations. The District will continue to work with the City of Sacramento to support decision-making to improve air quality.