Aclima partnered with Google to develop hyperlocal measurements of Carbon Dioxide (CO₂), Ozone (O₃), Nitrogen Dioxide (NO₂), Nitric Oxide (NO), Methane (CH₄), Black Carbon (BC), and fine particulate matter in San Francisco Bay Area, Los Angeles, and the California Central Valley. They affixed fast-response laboratory-grade air quality sensors to Google Streetview cars, which means they are able to measure block-by-block changes in AQ and the impacts of point sources. While the dataset is not completely publicly available, researchers (including community scientists) can request access through this Google Form! It takes them around a week to review your request.

Check out their website and this paper for more information.