A Google Streetview car equipped with an anemometer on top to measure wind speed, and an air quality monitoring station in the trunk. (Google/Aclima)

For the very real and detrimental impact that pollution has on our health, air quality is a surprisingly hard thing to measure. In the city, it can vary from block to block, neighborhood to neighborhood, and many times the current network of sensors just doesn’t pick up on fine-scale pollution events that could also lead to a spike in your asthma.

Aclima, a San Francisco-based air quality technology company, aims to address the problem by going mobile. They’ve partnered with Google to equip Street View cars with fully-loaded air quality monitoring stations. Starting this fall, three air quality cars will be buzzing around San Francisco, with the hopes of using the data to inform community decisions and new science and health studies.

While the project is just focused on San Francisco now, the vision is much larger. Imagine that while these Google cars zip around the city taking photos of your neighborhood, they will also be monitoring pollution levels — ozone, carbon monoxide, methane, particulate matter and volatile organic compounds, to name a few — across space and time.

“Many things affect air quality – everything from our transportation and energy choices, to green space and the weather,” said Davida Herzl, Aclima co-founder and CEO. “Understanding these complex relationships is critical to managing and improving air quality.”

There are quite a few metro areas in the U.S. where the weather is dominated by what meteorologists call micro-climates — small areas where weather can be quite different than the surrounding large-scale environment. In the San Francisco Bay Area, for example, the combination of ocean, bay and mountains can lead to daytime temperatures to range from 60 degrees in the city of San Francisco to 90 degrees on the other side of the bay during the summer months.

In addition to making it an interesting place to forecast, the micro-climate phenomenon can also add variability to the air quality from one neighborhood to the next. If air quality sensors that are managed by the Environmental Protection Agency are spaced too far apart, they might miss fine-scale changes in pollution levels, whether because of a localized thunderstorm that’s washing away pollution in one part of the city, or because there’s a big traffic jam on the highway.


Data from the 2014 field test in Denver, showing ozone reaching its peak around 4 p.m. — coinciding with the hottest time of the day. (Aclima)

“The monitoring network is designed for air quality regulation, but does not give a detailed picture of a community or urban area such that people can get a real sense of what air pollution is around their immediate surroundings,” Aclima said in a press release.

Putting the sensors on cars and releasing them into the wild eliminates the inherently static nature of the monitoring network. “Mobile air quality sensing gives us a picture of the variability. It fills in those missing pixels,” said Melissa Lunden, Director of Research for Aclima. “You can see how traffic patterns impact pollution at a really granular level over the span of a day to a week.”

Aclima and Google have already tested the technology in Denver in 2014 — the cars were in the field for a total of 750 hours, delivering 150 million data points that were verified next to the existing EPA monitoring sites. The field test resulted in a fully-mapped dataset that you can explore through time. It can tell you when the air quality is best and worst in your neighborhood, even on your street.


Around 7 p.m. ozone has dropped and nitrogen dioxide is increasing — this is the best time of the day for outdoor exercise. (Aclima)

You can play around with the Denver data in an interactive tool on Aclima’s website.

If you happen to be out in San Francisco and see a Google car, you can tell if it’s crunching air quality data by checking to see if there’s an anemometer on top.