How Polluted Is the Inland Empire? Sensor-Embedded Cars Reveal the Truth

A New Approach to Monitoring Air Quality in California

Imagine having a detailed map of the air quality in your neighborhood, down to the block level. This is the goal of the Statewide Mobile Monitoring Initiative (SMMI), a groundbreaking project that has deployed specially equipped vehicles across 64 communities in California. These cars, which resemble self-driving vehicles like those from Waymo, are collecting highly detailed data on air pollution in areas that have long been affected by environmental injustice.

The initiative is funded by the state of California and aims to provide policymakers and clean air advocates with an in-depth understanding of pollution sources and their impacts. It focuses particularly on underserved communities, including neighborhoods near warehouses or communities of color, which have historically faced higher levels of air pollution.

Davida Herzl, co-founder and CEO of Aclima, a San Francisco-based company supplying the vehicles for the mapping effort, explained the significance of the project. “It gives you an extremely rich picture of where pollution is coming from, who’s causing it, what’s causing it, and how long it’s going to be in the environment,” she said. “Having this kind of data means that we can answer these difficult questions.”

Air pollution can vary significantly from one block to another due to factors such as land use and industrial activity. With hyperlocal data, experts can better understand the causes of pollution and develop targeted solutions.

The Technology Behind the Effort

Aclima’s vehicles are equipped with advanced sensors that measure various pollutants, including black carbon or soot, which is both hazardous and contributes to climate change. These sensors collect real-time data as the vehicles drive through communities, providing a more comprehensive view than stationary monitors.

Josh Steele, an Aclima driver, recently drove one of the vehicles through Corona, following a pre-set route that included neighborhoods and major highways like the 91 Freeway. The vehicle featured a rooftop sensor resembling something from the Star Wars universe, along with another sensor on the passenger window. Both devices feed data into computers in the trunk, allowing for continuous monitoring.

Steele, who lives in Lake Elsinore, drives over 170 miles during his eight-hour shifts. Drivers work staggered schedules to ensure round-the-clock measurements, which are then stored in a database accessible in real time.

Focus on Underserved Communities

The 64 communities being mapped were selected based on their need for focused action under the Community Air Protection Program, a state initiative created by a 2017 law. The Inland Empire, known for its notoriously poor air quality, is one of the primary areas of focus. Residents there face higher rates of asthma and other health issues linked to pollution.

Community activists have long pointed to the region's sprawling logistics industry as a major contributor to air pollution, with diesel exhaust from trucks and freight trains being a key source of contaminants. A NASA-funded study published in 2024 found that ZIP codes with a high concentration of warehouses had higher levels of airborne pollutants.

Ana Gonzalez, executive director of the Center for Community Action and Environmental Justice, highlighted the importance of the mobile monitoring effort. Unlike traditional sensors, the vehicles can measure a wider area and follow truck routes, providing more accurate data.

Funding and Expansion

The $27 million mapping effort is funded by California’s Cap-and-Trade Program, which sets emissions caps and allows companies to buy allowances for pollutants. The initiative includes 36 vehicles and 102 drivers, with seven Aclima cars operating in the Inland Empire.

In addition to the Inland Empire, the program is expanding to Central and Northern California, covering areas such as Fresno, Sacramento, and the East Bay. The data collected will be publicly available, offering transparency and empowering communities to advocate for cleaner air.

A Step Toward Environmental Justice

Herzl emphasized that the initiative is about government accountability and community engagement. “This is really about government delivering on its promises to be able to actually do something about” air pollution, she said. “It’s a community response. It’s an act of listening, it’s an act of responding. And I think that has really profound consequences for democracy.”

As the project continues for at least eight months, the data gathered will serve as a critical tool for addressing environmental inequalities and improving public health across California.