California Air Resources Board

Project Introduction

The Statewide Mobile Monitoring Initiative (SMMI) was designed to attain a comprehensive dataset of criteria pollutants, toxic air contaminants, and greenhouse gases, create a data portal for public to access and visualize SMMI data, and conduct inclusive community engagement to better understand and address community concerns. This project provides an opportunity to complement AB 617 statewide air monitoring activities by engaging communities beyond those currently selected under the Community Air Protection Program, providing data to fill air monitoring gaps and support additional actions to reduce emissions and exposure. Read the September 2024 project press release and June 2025 launch of monitoring press release, or watch the video to learn more.

Project Background

CARB received $27 million through legislative appropriation to conduct mobile air monitoring in communities across the state. CARB selected Aclima, a California Public Benefit Corporation that specializes in hyperlocal air quality mapping and analysis, through a competitive solicitation process called a Request for Proposals (RFP). The RFP was released on January 22, 2024 to solicitate proposals to carry out primary tasks, such as community engagement, mobile monitoring, data management, and data analysis and visualization. The contract was approved on June 14, 2024 and continues through June 12, 2026.

Project Summary

Aclima and their subcontractors conducted mobile monitoring of criteria pollutants, greenhouse gases, and toxic air contaminants in Community Air Protection Program (CAPP) Consistently Nominated AB 617 Communities (CNCs) using a combination of 42 Aclima mobile platforms and 3 partner mobile laboratories (operated by UC Berkeley, UC Riverside, and Aerodyne).

The project held a virtual public kick-off meeting on September 17, 2024 and a Project Expert Group (PEG) was formed to guide SMMI throughout the project period. The PEG partnered with Aclima to co-develop a community engagement plan (CEP) and community air monitoring plans (CAMPs). These documents guided engagement and monitoring activities and ensured objectives aligned with community needs and goals. Specific monitoring areas were determined through a community engagement process and documented in CAMPs. At least 60% of monitoring was require to be conducted to benefit California Climate Investments priority populations.

Mobile monitoring began with a broad area monitoring strategy, through which Aclima's fleet of Mobile Platforms collected data within each community boundary, gathering repeat measurements at different times of day and days of the week across a 9 month period from June 30, 2025 to March 31, 2026. Aclima and its research partners (partner mobile laboratories including UC Berkeley, UC Riverside, and Aerodyne) also conducted targeted area monitoring focusing on specific air pollution concerns at smaller spatial scales. This involved monitoring over relatively smaller areas for short time periods in each community (approximately a few days to a week) and was designed to complement the broad area monitoring coverage by providing more in-depth information about a specific area of concern. Aclima platforms measured criteria pollutants and surrogates for air toxic contaminants; partner mobile laboratories conducted speciation analysis of air contaminants (e.g., benzene and formaldehyde). A complete list of compounds measured by Aclima and each partner mobile laboratory can be found in Appendix I.
 

SMMI is part of California Climate Investments, a statewide initiative that puts billions of Cap-and-Invest, formerly known as Cap-and-Trade, dollars to work reducing greenhouse gas emissions, strengthening the economy, and improving public health and the environment — particularly in disadvantaged communities.