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Cleaner air could cut infant deaths in sub-Saharan Africa

Dar es Salaam, Tanzania. (Credit: Andrew Moore/Flickr)

Even modest improvements in air quality could lead to substantial reductions in infant mortality in developing countries, a new study shows.

Exposure to particulate matter in sub-Saharan Africa led to 400,000 otherwise preventable infant deaths in 2015.

“Many wealthy countries have recently used legislation to clean up their air,” says coauthor Marshall Burke, assistant professor of earth system science in the School of Earth, Energy & Environmental Sciences at Stanford University and coauthor of the study in Nature.

“We find that if countries in Africa could achieve reductions in particulate matter exposure similar to wealthy countries, the benefits to infant health could be larger than nearly all currently used health interventions, such as vaccinations or food and water supplements.”

“…we don’t yet know how big a threat poor air quality is relative to other common health risks like poor nutrition and infectious disease.”

Led by Sam Heft-Neal, a research scholar at Stanford’s Center on Food Security and the Environment, the research team combined 15 years of survey data on nearly 1 million births across sub-Saharan Africa with satellite-based measurements of particulate matter, an important contributor to poor air quality. The mixture of microscopic particles in the air can cause serious health effects when inhaled.

“We know that breathing dirty air is bad for your health,” says Heft-Neal. “But in developing countries in particular, we don’t yet know how big a threat poor air quality is relative to other common health risks like poor nutrition and infectious disease.”

Understanding the impact of poor air quality in developing countries has traditionally been difficult, as most do not have on-the-ground pollution monitors or vital registration data recording birth outcomes.

To overcome these constraints, the researchers compiled data from 65 household surveys across 30 sub-Saharan African countries spanning from 2001 to 2015. Using new satellite-based measures of ambient particulate matter, they then compared the particulate matter each infant was exposed to while in utero and after birth. From this, they could relate exposure to particulate matter with health outcomes.

“The results were sobering,” Burke says. “We find that mortality rates are substantially higher for infants exposed to higher levels of particulate matter.”

The findings show that high particulate matter concentrations were responsible for 22 percent of infant deaths from 2001 to 2015. They also found that this number has not decreased over the past 15 years and remains unchanged even in wealthier households.

The group’s estimate of the effect of particulate matter exposure on mortality is about three times larger than existing estimates, suggesting poor air quality is an even bigger problem than currently believed.

The main explanation for these larger estimates, the authors say, is that exposure to particulate matter can lead to a range of negative health effects, including lower birth weight and impaired growth in the first year of life, beyond those typically considered in health analyses.

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One of the study’s most important implications is that relatively small decreases in particulate matter concentrations could result in major reductions in mortality.

The researchers conclude that finding cost-effective ways to reduce particulate matter exposure should be a research and policy priority.

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“We now have a better sense of the immense benefits of air quality improvements for infant health,” says Heft-Neal. “Next we need to establish how these improvements can be achieved.”

Additional coauthors are from Stanford and from the University of California, San Diego. The Stanford Environmental Venture Projects program and the National Science Foundation funded the work.

Source: Stanford University