English: A Plume Labs Flow 2 air pollution sensor (right) linked by Bluetooth to a smartphone that draws (in real-time or whenever you sync the sensor) little maps of the pollution levels of the places you visit (left). I used it for the rough-and-ready air pollution tests in my 2021 book Breathless: Why Air Pollution Matters and How it Affects You.

It's not the most accurate or reliable sensor, in my experience, but it gives a good idea of how air quality changes as you wander through the world, so it's very educational and great for kids. It's fine for simple comparisons of clean and dirty places; not so good for absolute measurements, though it does collect an awful lot of data you can export into spreadsheets and process however you like. It measures particulates (PM1, PM2.5, PM10), nitrogen dioxide, and volatile organic compounds (VOCs).

As of April 2023, it's no longer on sale.

Our images are published under a Creative Commons Licence (see opposite) and are always free for noncommercial use. This one is also available for commercial use under a CC BY-SA 2.0 licence. Please contact us directly via our website for more details about licensing.