Six Sensor-Fitted Buses Could Cover 17.6% of Amsterdam in a Day

The results point to a demographic dividend as well as a geographic one. The sensors mounted on transit vehicles did not simply reach more streets; the demographic profile of the areas measured came closer to reflecting the citywide average than the profile captured by fixed stations alone.

What difference does a handful of sensors make?

Co-author Titus Venverloo, a program developer at the AMS Institute and researcher at the MIT Senseable City Lab, said cities still have considerable room for improvement on social inclusion in how they design monitoring networks.

"Many cities could do better at ensuring that their monitoring systems properly account for all population groups," Vennerloo said. "When placing sensors, there is a risk that air pollution affecting specific groups may be overlooked."

He added: "By expanding the monitoring network to include sensors on public transit, in addition to fixed sensors, we are taking a further step toward a fair and comprehensive environmental monitoring network."

Lead author Petar Koljenšić, a researcher at TU Delft, MIT and the AMS Institute, emphasized that even cities with limited fleets can achieve large gains.

"With a selection of 20 equipped vehicles, virtually the entire accessible city can be monitored in a demographically sound manner," Koljenšić said. "It's not about installing thousands of expensive sensors, but about strategically deploying the mobile sensors on the right routes."

Can other cities copy the approach?

The method scales readily, according to the researchers. To help planners elsewhere apply it, the team built an interactive online dashboard that lets local authorities simulate their own scenarios and calculate how many vehicles, and which specific routes, they would need to achieve fair environmental monitoring in their city.

While the current analysis focuses on air quality, the same sensors could measure temperature and noise levels, extending the tool to heat and noise pollution — two growing concerns for dense urban populations.

The central message of the study is one of efficiency rather than expense: effective environmental monitoring does not necessarily require more fixed sensors, but a smarter use of the existing network and public transit. A city bus, in other words, can double as a moving measurement station without any new infrastructure beyond the device itself.

The findings carry caveats. The study models coverage and representativeness rather than reporting long-term pollution measurements, and the analysis concerns Amsterdam, a city with an extensive tram and bus network. A follow-up study now underway should test the concept further: sensors are being installed on public transit in Rotterdam, with results expected within two months.

The paper is published as Petar Koljenšić et al., "Optimizing environmental sensing on public transport to cover broader demographics in Amsterdam," Scientific Reports (2026), DOI: 10.1038/s41598-026-77183-4.

Fair monitoring, the researchers suggest, may be as close as the next bus.