More data points from more sensors means more reliable pollution maps and more practical solutions to the problem of poor air quality in our cities.

In Chicago, a group of volunteers have been lugging around around mobile pollution sensors on a regular basis around certain parts of the city for the past six months. They are a part of a project funded by the US Environmental Protection Agency (EPA).

They found out that while their neighborhoods in the South Loop and Dearborn Park had generally decent air quality, there were also intermittent, lung-damaging spikes of pollution spewed out by a passing bus or truck.

According to the Chicago Tribune:

Breathing even small amounts of particulate matter, commonly known as soot, can inflame the lungs and trigger asthma attacks. Long-term exposure can cause heart disease, increase the risk of developing cancer and shave years off a person’s life.

Unlike the thick clouds of pollution that choked cities during the past century, the soot particles that concern public health researchers today are so small that thousands could fit on the period at the end of this sentence.

Since the amount of vehicle exhaust and factory pollution can vary widely within neighborhoods and at different times of day, the new wave of portable and stationary sensors can find pockets of dirty air that go unnoticed by authorities.

Chicago operates 17 air monitoring sites but that is far too small a number to cover the city in detail. Other scientists and citizens’ group have joined the effort to map air quality. The University of Chicago-based researchers at the Urban Center for Computation and Data are installing 500 air quality monitors at lampposts throughout the city. They have to finish installing the project by the end of 2018. The non-profit Environmental Law and Policy Center have given away miniature sensors to volunteers measuring soot levels in 35 of Chicago’s community areas.

The Chicago Tribune reports:

The testing found high levels of soot along major thoroughfares and at clogged intersections throughout the city. Howard Learner, the group’s executive director, said as more data is accumulated, it can nudge city officials and citizens to make changes.

For instance, CTA bus drivers could stop idling at busy transit stations or transportation engineers could tweak traffic signals to reduce backups when pollution hot spots are detected. People could rely on the maps to avoid dirty air while commuting or walking around the city.

“We already have reasonably verifiable data that can be collected by people engaged in their communities, and the equipment is only going to get better,” said Learner, who co-chaired an EPA task force that last year urged the agency to boost its support for citizen science. “By identifying problems in ways that weren’t possible before, it opens up new opportunities for solutions.”