On the distribution of low-cost PM2.5 sensors in the US: demographic and air quality associations.

BACKGROUND Low-cost sensors have the potential to democratize air pollution information and supplement regulatory networks. However, differentials in access to these sensors could exacerbate existing inequalities in the ability of different communities to respond to the threat of air pollution. OBJECTIVE Our goal was to analyze patterns of deployments of a commonly used low-cost sensor, as a function of demographics and pollutant concentrations. METHODS We used Wilcoxon rank sum tests to assess differences between socioeconomic characteristics and PM2.5 concentrations of locations with low-cost sensors and those with regulatory monitors. We used Kolomogorov-Smirnov tests to examine how representative census tracts with sensors were of the United States. We analyzed predictors of the presence, and number of, sensors in a tract using regressions. RESULTS Census tracts with low-cost sensors were higher income more White and more educated than the US as a whole and than tracts with regulatory monitors. For all states except for California they are in locations with lower annual-average PM2.5 concentrations than regulatory monitors. The existing presence of a regulatory monitor, the percentage of people living above the poverty line and PM2.5 concentrations were associated with the presence of low-cost sensors in a tract. SIGNIFICANCE Strategies to improve access to low-cost sensors in less-privileged communities are needed to democratize air pollution data.