Robust relationship between air quality and infant

mortality in Africa

We know that breathing dirty air is bad for human health, and recognition of this fact has caused many countries in the developed world to adopt policies to clean up their air.  Many developing countries, though, still face very high levels of air pollution, and we still know surprisingly little about what these high exposure levels mean for health, particularly in developing-country contexts where other threats to health – from poor nutrition to infectious disease – loom large.   

Relative to these other threats, how important is the harm caused by air pollution?  Answering this question is important for figuring out policy priorities. Answering it has also been hard:  in most poor countries, air quality monitors are unavailable, and traditional methods for monitoring air quality don’t adequately account for the burning of biomass – things like wood and animal waste – common in these countries.

Our study shows that air pollution is a much more important cause of excess mortality in sub-Saharan Africa than previously thought.

In particular, we find that that exposure to particulate matter is responsible for more than 20% of infant deaths in Sub-Saharan Africa, and that this exposure led to about 400,000 excess infant deaths in our 30 study countries in 2015 alone.  These large effects appear to be borne by both poor and wealthy households equally, and they also do not appear to have declined over time.

Finally, we calculate the benefits of relatively modest improvements in air quality -- e.g the amount of air quality improvements the US achieved under the clean air act a few decades ago, or roughly a 25% reduction in particulate matter at average levels in Africa.  With even these modest improvements, we calculate that the health benefits (in terms of infant mortality reductions) would be larger than nearly all known health interventions, including vaccines and nutritional supplementation. This is not to say that these other interventions are not important -- they are very important! -- but instead that cleaning up the air can also yield enormous benefits.