The rising tide of urban air pollution mapping

What do Houston, London, and San Francisco have in common? You might be thinking about great food, an excellent job market or a thriving arts scene, but the answer is that all three cities are taking action to improve their understanding of an often invisible urban threat: air pollution.

Recent studies have uncovered that the impacts of air pollution are far worse than previously understood – air pollution can impact mental health, lung development, and even stock market performance. There’s now a trend underway in how cities, which often bear the brunt of these impacts, are tackling the air pollution threat by measuring air pollution as a means to better manage it.

Methodologies and innovations first piloted in Oakland, California are now enabling cities to map air pollution on a block-to-block scale. The latest developments, in the Bay Area and in Houston, showcase a growing demand for clean air innovations and offer a new roadmap for measuring air pollution across America. 

Air pollution mapping in San Francisco

The Bay Area Air Quality Management District (BAAQMD), which regulates air pollution in nine counties around San Francisco, recently authorized moving forward on a $6 million contract with Aclima Inc. to map the area’s air pollution over the next two years.

Aclima Inc. proposed to deploy its mobile air pollution sensors on vehicles throughout the Bay Area and make that data available to the public via an online portal that can help communities better understand local pollution patterns. BAAQMD plans to use these data to help target areas where further investigations are needed, potentially leading to better enforcement of pollution rules.

This move follows an investment by C40 Cities, partnering with the Greater London Authority in a coalition led by Environmental Defense Fund Europe, in an effort to map pollution in the UK capital and share the data with the public.

Proof of concept: Houston

Last year the city of Houston worked with EDF to successfully pilot an air quality mapping project using municipal vehicles outfitted with air quality detection systems by TD Environmental.

And just today, newly released resources show that this model of using municipal vehicles as urban pollution mapping fleets works, and is replicable:

  • Two municipal vehicles collected data on 2,527 miles of city roads, just by driving their regular routes. The municipal mapping model filled in the gaps between stationary monitors with far more spatially-resolved data.
  • The car-top air pollution “hats” were low-fuss, easy to use, rugged systems that worked well, even in the Houston summer. The instructions on how to construct your own mobile air pollution monitoring system and the programming for data management of this system are open-source, available here.
  • An analysis of part of Houston’s public health fleet shows that 30 vehicles could have mapped 30% of the city’s miles of roads with seven passes over six months – a new level of insight into air pollution.

A roadmap for measuring and mapping air pollution

Our experience and the work of others around the world shows that investing in hyperlocal mapping can drive impact when it follows a few best practices, including:

  1. Rigorous data collection: The BAAQMD project—consistent with the practice of hyperlocal mapping efforts in Oakland, Houston and London—will rely on repeated passes of area roads. Without repeated passes, mobile data may not accurately capture spatial patterns of pollution.
  2. Suitable instrumentation: The project plan starts with mobile pollution monitoring instruments that respond fast enough to achieve the desired spatial resolution and whose accuracy and precision have been independently verified. The plan also includes an ongoing data validation strategy that begins with ensuring the instruments are properly calibrated throughout the study period.
  3. Public access: Sharing air pollution maps with the public is critical. BAAQMD, Houston and London will post validated data to public portals so people can better understand pollution patterns.
  4. Data-driven action: To provide the most value, the sharing of hyperlocal maps should enable leaders and advocates to achieve actions to improve air quality. At their best, maps can stimulate engagement and direct people towards action. At their worst, content without context runs a real risk of numbing people to yet another threat they feel they can’t do anything about. Anyone releasing hyperlocal maps should have a plan for continuing the conversation after maps are released to explain the results and respond to questions from community members who want to use the data to enable decisions around possible steps to reduce pollution.
  5. Transparency into methods and data: Transparent disclosure of data in as raw a form as possible and analysis methods allows errors or biases in results to be discovered. Many judgment calls go into the process of turning “raw” air pollution measurements into validated data, final maps, and everything in between. To maximize the value of public investments and generate more insights from the resulting data, agencies should leverage the ingenuity of the scientific community by granting them access to all the data. EDF, in collaboration with the Air Sensors Workgroup (consisting of experts from academia, government agencies, sensor manufacturers, and others from the private sector), are working on developing an open-access, open-source repository for air quality data derived from low and medium-cost sensors. This level of transparency is an integral part of credible hyperlocal mapping.

As the data starts to drive local action, hyperlocal mapping will move from the realm of scientific research to that of public policy and corporate environmental leadership. That’s good news, especially for communities that are experiencing the devastating effects of air pollution first-hand.

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