firmed recently in 2020, which suggest an annual standard of 12 micrograms per cubic meters, and a daily corresponding standard of 35 micrograms per cubic meters. Further, a 2016 WHO study (WHO, 2016) emphasizes that fine particle pollution disproportionally affects urban areas in Uganda with PM2.5 concentration 40 percent higher than in rural areas. This estimated urban-rural gap in pollution exposure is wider in Uganda than in India, China and the United States.<sup>6</sup> Importantly, as shown in Appendix Figure A10, while both Chinese and Indian PM2.5 pollution levels have been declining since 2010 by 24 percent and 5 percent respectively, pollution in Uganda has been _increasing_ from 44.8 to 50.5 micrograms per cubic meter, or an increase of 13 percent from 2010 to 2017.

**Productivity and health effects of pollution.** Such high and growing pollution levels are a serious concern as the impacts of air pollution on health and productivity are well established. Pope and Dockery (2006) argue that PM2.5 has been shown to be the deadliest component of air pollution. Early work provides evidence on how plausible exogenous changes in pollution affect health as measured by infant mortality (Chay and Greenstone 2003) and mortality due to cardiorespiratory diseases (Ebenstein et al. 2015). Deryugina et al. (2019) estimate that a 1 microgram per cubic meter increase in PM2.5 concentration (10 percent of the mean) leads to 0.69 more deaths per million elderly over the following three days (0.18 percent increase relative to the average mortality rate). Anderson (2020) identifies a causal link between long-term exposure to air pollution from road traffic and adult mortality.

Air pollution, including fine particle pollution such as PM2.5, also has adverse effects on workers’ labor supply and productivity. At the extensive margin, pollution negatively affects labor supply as first shown for the United States by Ostro (1983) and Hausman et al. (1984). Hanna and Oliva (2015) exploit a natural experiment to identify a negative causal effect of air pollution on labor supply in Mexico, and Aragon et al. (2017) show similar results for Peru. On the intensive margin, numerous studies document the negative effects of particulate matter on worker productivity in both developed and developing countries (Graff Zivin and Neidell 2012, Chang et al. 2016, Adhvaryu et al. 2019 and Fu et al. 2021).

**Urbanization, motorization and pollution emissions** . Road traffic is widely recognized as a common source of PM2.5. With rapid urbanization growth and increasing incomes that have been shown to speed up motorization, the challenges brought by air pollution in the developing world can only be expected to rise. Across Africa, the urban population is expected to triple by 2050 (Collier 2017). Like other African countries, Uganda has experienced rapid urbanization in

> 6The corresponding median pollution concentrations (micrograms per cubic meters) reported by the same WHO study for Uganda, China, India and the United States are: 57 (overall) and 80 (urban only) for Uganda; 54 (overall) and 59 (urban only) for China; 62 (overall) and 66 (urban only) for India; and 8 (overall) and 8 (urban only) for the United States.

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