Fig. 3: Impact of the economic shutdown on (left) PM_2.5 concentrations and (right) mobility.

Points show heterogeneous changes across CBG characteristics estimated from difference-in-differences models, along with 95% confidence intervals. Intervals that include zero indicate that there was no differential reduction in exposures across the given gradient. a, Changes in daily PM_2.5 concentration across the shutdown estimated for various socioeconomic variables. The coefficient for mobility is the estimated difference between 0 and 100% of time spent at home; the coefficients for (ln) income, road and population density each represent the impact of an approximate doubling for each variable. b, Similar estimates with mobility as the dependent variable. c,e, Changes in PM_2.5 concentrations over the shutdown period across different racial and ethnic population shares, estimated with different physical and socioeconomic control variables (labels on left). The coefficients correspond to the expected changes between 0 and 100% population share at the CBG level. See Supplementary Tables 2 and 3 for values. d,f, Similar estimates, but with mobility as the outcome instead of PM_2.5. Values are given in Supplementary Tables 4 and 5. All four panels compare the post-shutdown difference from 2020 to 2019 to the pre-shutdown difference to account for seasonality. In addition, estimates were weighted to reflect the distribution of incomes, population shares and other location characteristics across all block groups in California and correct for the endogenous sampling of ground station locations (Extended Data Fig. 2b, Methods and Supplementary Information). The ‘Base’ model includes CBG and day-of-year fixed effects, as well as weather controls; other models incorporate the noted controls, or exclude weather, and ‘All’ includes everything.