209Novel indicator of air pollution control efficacy: analysis of 196 countries from 2000 to 2016

Background PM2.5 concentration is different with the same CO2 emission across countries, which might because of different air pollution control efficacy. But there is no indicator to reflect the level of air pollution control efficacy in previous studies. We aimed to develop such an indicator, and to evaluate its global and temporal distribution and its association with country-level health metrics. Methods A novel indicator, PM2.5 concentration per unit per capita CO2 emission (PC), was developed to show the air pollution control efficacy. We estimated and mapped the global average distribution of PC and PC changes during 2000-2016 of 196 countries for the first time. Gini coefficient was used to show the inequity of PC among different countries. Pearson correlation coefficients and Generalized Additive Mixed Model (GAMM) were used to evaluate the relationship between PC and health metrics. Results PC varied by country with an inverse association with GDP per capita. PC showed a declining trend globally from 2000 to 2016. The most remarkable decreases were observed for countries in Central Africa like Chad, Democratic Republic of Congo and Niger, then China and India. The international inequality of PC has also decreased. The Pearson correlation coefficients between PC and life expectancy at birth (LE), Infant-mortality rate (IMR), Under-five mortality rate (U5MR) and logarithm of GDP per capita(LPGDP) were -0.566, 0.646, 0.659,-0.585 respectively(all P-values <0.05). Compared with PM2.5 and CO2, PC could explain more variation of LE, IMR and U5MR. Conclusions PC might be a good indicator of air pollution control efficacy and was related to important health indicators. Our findings provide a new way to interpret health equity across the globe from the point of air pollution control efficacy. Key messages air pollution, climate change, health equity, air pollution control efficacy our study developed a novel air pollution control efficacy indicator named PM2.5 concentration per unit per capita CO2 emission (PC). In the context of global climate change, PC is a good indicator to deal with air pollution for policymakers.