4
Outlook and Policy Implications
This report provides an estimate of the global cost of PM2.5 ambient and household air pollution in 2019 based on the GBD 2019 study. It thus represents an update of the estimated cost in 2013 reported in World Bank and IHME (2016) that was based on the GBD 2013 study. This report distinguishes itself from the 2013 estimate in important aspects. It is based on • Revised exposure-response functions from the GBD 2019 study that differ from the functions from the GBD 2013 study for several health outcomes; • Revised global ambient PM2.5 population-exposure estimates from the GBD 2019 study that are based on calibration from a substantially larger database of PM ground-level measurements than the data used for the GBD 2013 study; and • Inclusion of an estimate of the cost of morbidity based on estimates of years living with disease from PM2.5 air pollution reported by the GBD 2019 study. Health damages and costs of PM2.5 air pollution are staggering, especially in developing countries, globally reaching 6.4 million deaths and 93 billion days lived with illness in 2019, with a welfare cost of $8.1 trillion, equivalent to 6.1 percent of global GDP (PPP adjusted). This estimated cost for 2019 is 40 percent higher in real terms than the estimate for 2013 in World Bank and IHME (2016). The reasons for the higher cost estimate are mainly changes in exposure-response functions, substantially higher estimate of global ambient PM2.5 exposure due to improved methodology and ground-level PM monitoring data availability, and inclusion of an estimate of the cost of morbidity. The higher estimate of global ambient PM2.5 exposure is more due to improved methodology and availability of ground-level PM monitoring data than actual worsening of global ambient PM2.5 air quality from 2013 to 2019, although the exact contribution of each of these two factors is difficult to ascertain. About 85 percent of the total global cost of health damages in 2019 is from premature mortality and 15 percent from morbidity. Cost of morbidity as a share of total cost varies from as low as 4 percent to as high as 33 percent across countries. 23
