More and more people are making their own air pollution measurements and using these to press for action from national and local governments. Last year Mark Tebbutt installed Chorley’s seventh air pollution monitor. Since 2013 Tebbutt, his family and friends have been buying and operating their own air pollution instruments. These are mounted on garden fences and on the sides of houses across the Lancashire town. You can find their data online alongside those from more than 30,000 citizen scientists around the world. Tebbutt’s network often measures particle pollution in the evenings, as people sit around their fires: “I began making measurements out of concern about wood smoke pollution from the proliferation of domestic solid fuel burning in Chorley. I wanted to prove to the council that the area has an air pollution problem. I also use the real-time levels to lobby various people and agencies on social media.” Air pollution concerns are not confined to towns and cities. Jo Clark, who lives in rural north Wales, also has her own monitor: “I have been able to show others, such as my local authority, how the particle pollution goes up and down over the days, months and years – and how it can vary from the very general ambient levels forecast and reported by Defra or the Welsh government.” The London mayor and Bloomberg Philanthropies are taking a different approach by distributing 60 free Breathe London sensors to community groups. Andrew Grieve, who works on the project at Imperial College London, says: “In our experience the groups see collecting local air quality data as an opener to discussing broader visions for their neighbourhood with their community and as a way to get a seat at the table with city authorities.” That is certainly how some of the groups are seeing it. Rectory Road residents’ association in north London, which has joined the Breathe London project, said: “As a large BAME community, we feel we have been ignored; our asks haven’t been met and we are struggling to have any serious commitment and action to tackle toxic air pollution.” Others including Victoria Park Harriers and Tower Hamlets athletics club are keen to use the data to help their community at times when air pollution is bad and to help them advocate for change. Governments have struggled to act on the concerns of citizen air-quality scientists and harness the opportunities they present. Citizen science has a long history in observations of the natural world. For example, ornithological research relies heavily on volunteer observers who share their data but air pollution measurements are usually the domain of university or government scientists that use standardised approaches and expensive instruments. Although less accurate, citizen measurements may help to raise awareness of air pollution problems and make the case for more action.