Interviewer: Adam Levy
Air pollution causes a vast number of deaths across the globe. But what is that number? Back in 2015, atmospheric scientist Jos Lelieveld told the
Nature Podcast
about his research on the lives air pollution claims.
Interviewee: Jos Lelieveld
This is an astounding number of more than 3 million premature deaths per year, worldwide, related to air pollution. It’s quite much higher than HIV/AIDS and also for example, malaria.
Interviewer: Adam Levy
Jos calculated this huge figure by using modelling to capture a global picture of pollution and connect this to pollutants’ documented impact on health. But such a global picture can’t fully describe important regional details and this week a study is coming out focusing or air quality in a region that’s often been overlooked.
Interviewee: Jen Burney
What struck us was that most of these studies were in middle- or high-income countries.
Interviewer: Adam Levy
This is Jen Burney, one of the authors of this week’s paper.
Interviewee: Jen Burney
So, we look at sub-Saharan Africa in this study and that stands out for having very little data, really, on how much damage air pollution is causing.
Interviewer: Adam Levy
Jen and her colleagues set out to fill in some of the gaps to understand how air pollution affects infant mortality in sub-Saharan Africa. But there’s a reason the health effects of air pollution are studied so little in this region - there just isn’t as much on-the-ground air quality data as in, say, Western Europe. To get around this the team used remote sensing, teasing apart observations from satellites to estimate the air quality at ground level. They then gathered 65 surveys that capture household health. Carefully combining these two data sets allowed the team to compute the link between the deaths of infants and air pollution.
Interviewee: Jen Burney
Our study here shows that air pollution is actually a much more important cause of excess mortality in sub-Saharan Africa than previously thought. And we find that particular amount of pollution is responsible for more than 20% of infant deaths in our study countries and that exposure to that pollution led to about 400,000 excess infant deaths in that region in 2015 alone. We were surprised to see an effect that was so large and so much larger than existing estimates of mortality. So, this is somewhat sobering in terms of what air pollution really does and what the benefits might be from mitigating it.
Interviewer: Adam Levy
Jen isn’t the only one who found these results sobering. I called up Jos who authored the 2015 study to get his thoughts on these new figures.
Interviewee: Jos Lelieveld
It is quite an amazing result that has been represented in this paper and the number of premature deaths in infants is really large. But it is a very serious warning of what needs to be done to protect the health of children.
Interviewer: Adam Levy
This result may be a serious warning, but it’s one of many that seek to quantify deaths from poor air quality. How, then, does it fit with Jos’ 2015 calculation that around 3 million people die from air pollution globally per year?
Interviewee: Jos Lelieveld
If I now compare this study, we find that the numbers have gone up tremendously, so there is a large number of deaths that we have not yet accounted for properly.
Interviewer: Adam Levy
Jen and her colleagues’ study may be accounting for additional deaths because they’re not assuming air pollution kills people solely through respiratory infections. Instead, the method simply looks at the relationship between infant deaths and the quality of the air. Their results are substantially larger than the numbers of deaths attributed to respiratory infections.
Interviewee: Jen Burney
And that does suggest that there may be pathways that are not just respiratory. Some of it could also just be that we’re only now uncovering these other channels of impact.
Interviewer: Adam Levy
Jos agrees that looking beyond respiratory problems is key to understanding the full impact of air pollution.
Interviewee: Jos Lelieveld
And of course, more research is needed to pinpoint what these other causes are but I think that determining that there is a problem here is already a very important first step.
Interviewer: Adam Levy
But this study doesn’t just show how many infants are dying in sub-Saharan Africa as a result of poor air quality. It sketches out the relationship between infant mortality and pollution levels and this shows the impacts that improving air quality could have.
Interviewee: Jos Lelieveld
One of the conclusions is also that, you know, with modest decreases of air pollution, one can achieve at least the improvement in health burden or disease burden in Africa that has been invested for other diseases. Air pollution is something that needs to be put higher up the agenda, because actually with relatively little means one can already do a lot.
Interviewer: Adam Levy
But at present, it’s all too easy for policymakers around the world to do little about air pollution. There’s a disconnect between the cause and the death. But Jen hopes that studies like hers and Jos’ will help make the damage caused by air pollution that much more visible.
Interviewee: Jen Burney
It’s one thing to know that poor air quality is bad for health and it’s another to be able to say that more than 20% of infant deaths in sub-Saharan Africa in 2015 were due to excess pollution, and to be able to estimate what the benefits would be for a given amount of mitigation. So, we really do hope that by providing this kind of cross-benefit analysis, in some ways, that we can incentivize more action on air quality.
