AQI stands for Air Quality Index and it is the number or colour that indicates how good or bad is the air quality in your area. The problem with the AQI is the way each governments calculates the air pollution and what parameters it uses to project this Index number/colour. For example, the USA Environmental Protection Agency (EPA) considers as breakpoint for a “Moderate” NO2 concentration the value of 101μg/m3, but the UK Department for Environment, Food & Rural Affairs (DEFRA) considers as breakpoint for a “Moderate” NO2 concentration the value of 201μg/m3. The difference is huge and the Index changes dramatically for each country and at the end people get confused.  The same rule applies for all the pollutants, PM2.5, SO2, O3, etc… Later they are combined all together to give us the final Index.

AQLI stands for Air Quality Life Index and only take into account the PM2.5 pollution. It is based on the finding that an additional 10μg/m3 of PM2.5 reduces life expectancy by 0.98 years. By combining this finding with satellite PM2.5 measurements around the world, the AQLI provides an insight into the global impacts of particulate pollution in local jurisdictions. The Index also illustrates how air pollution policies can increase life expectancy if pollution levels were reduced to the World Health Organization’s (WHO) safe guideline or existing national air quality standards, or by user-selected percent reductions.

Could the AQLI replace the different AQIs worldwide?

Although it gives a better insight into the impact the air pollution has to our lives, it will not be able to convince people in countries where the impact of air pollution doesn’t translate to high “Life Years Saved” numbers. For example, we can clearly see from the table below that if China adjusts their policies according to the WHO Guideline the population will have a benefit of 2.9 years. However, if Netherlands adjusts their policies according to the WHO Guideline the population will have a benefit of 0.3 years. This is rather a small number and I am afraid people won’t take it as serious in western countries as they should. In my opinion the AQLI has to take into account how our quality of life (not only life expectancy) is affected by the air pollution. We may live longer but sometimes inside hospitals, under expensive insurances and medicines that not everyone can afford even in US, Europe, etc.

Moreover, the data that you see on the table above (extracted from the original document which you can find below) do not reflect the real air quality an individual has been exposed in his a city/town/village. They have created an annual average PM2.5 concentration and the aggregations are population-weighted, which means this map won’t help an individual to understand the air quality in his/her area. For instance, there is a small town in my region called Carboneras, the population is small but there is a coal power plant there (equipped with 48 coal burners). People’s life expectancy from that village won’t reflect on the annual PM2.5 concentration because the populations is small.

Read the paper at https://aqli.epic.uchicago.edu/wp-content/uploads/2018/11/AQLI-Report.111918-2.pdf

Conclusion

I really admire this exceptional work which is done by Michael Greenstone and Qing (Claire) Fan because we need a global way to understand the air pollition and its effects. They have developed a tool which can help to inform local communities and policymakers in Asian countries about the benefits of air pollution policies in very detailed way.