Air pollution associated with infant mortality finds study

By Dr. Ananya Mandal, MDJun 29 2020

A new study from Stanford researchers shows that a rise in air pollution is associated with increased mortality rates among infants. This new article and its results were published today in the latest issue of the journal Nature Sustainability.

Researchers said that dust and changes in climate could be responsible for the rise in infant mortality in certain geographical regions, and addressing these problems could help bring down infant mortality rates. This study was funded by the National Science Foundation and the Robert Wood Johnson Foundation.

Why was this study conducted?

Infant mortality refers to the number of children dying before their first birthdays per 1,000 live births in a region. In recent times there has been much advancement in medical science, and with adequate maternal nutrition, breastfeeding, and vaccination programs, the infant mortality rates have been steadily declining. This decline has been especially encouraging in developed and developing nations.

Senior author of the study, Marshall Burke, an associate professor of Earth system science in Stanford's School of Earth, Energy & Environmental Sciences, said in a statement, "Africa and other developing regions have made remarkable strides overall in improving child health in recent decades, but key negative outcomes such as infant mortality remain stubbornly high in some places." He added, "We wanted to understand why that was, and whether there was a connection to air pollution, a known cause of poor health."

Risk of infant mortality from air pollutants

The researchers explained that children below five years of age are particularly vulnerable to particulate matter or tiny airborne particles that arise out of air pollution. These air pollutants and seemingly invisible dust particles are known to cause a wide range of health problems among children. These health problems include low birth weight and impairment or growth or growth retardation over the first year of life. Exposure to air pollutants also reduces the overall life expectancy in the children as they grow up. Some studies have suggested an overall life expectancy reduction by 4 to 5 years among individuals growing up in regions with high air particulate matter.

Air pollution and health impacts

One of the key measures to reduce the global ill-health burden is to quantify the actual impact of air pollution on health, wrote the researchers. Infant mortality is one such indicator. The situation, explain researchers is paradoxical. In developing and developed nations, infant mortality is lower because of better employment and better access to healthcare. On the other hand, these nations are also one of the most polluted countries because their development is determined by industrialization that leads to higher levels of air pollution. This was quite a "chicken and egg problem."

To understand if "air pollution leads to raised infant mortality" or "industrialization reduces infant mortality," the team isolated the effects of air pollution alone. Removing the variable of "industrialization and air pollution," they first concentrated on dust pollution in the Bodélé Depression in Chad that spreads over thousands of miles. This area is one of the highest dust polluted areas of the world, explained the researchers. Dust pollution is commonly found in West Africa and other areas of the continent.

What was done?

To understand the effects of the dust emissions, the team then analyzed 15 years of survey results from households across 30 nations around Sub-Saharan Africa. Nearly 1 million live births were included in the surveys. They compared the birth and death data of the children with satellite-detected changes in the air particle or particulate levels driven by the Bodélé dust storms. Association between the two parameters was studied to see if poor air quality was associated with adverse health outcomes in the children.

What was found?

Results revealed that around 25 percent rise in local yearly average particulate concentrations in West African regions meant an 18 percent rise in infant mortality rates. The team says that a similar paper in 2018 by the same team had also shown that 400,000 infant deaths in 2015 could be attributed to high particulate matter concentration in sub-Saharan Africa.

Conclusions and implications

The authors concluded that air pollution from natural as well as artificial sources, could be linked with raised infant mortality. They wrote that it is clear that air pollution alone is the "critical determining factor for child health around the world." Changing climate, they added, could be the reason behind natural sources of air pollution, and this could be corrected. The team explains that in the Bodélé Depression, the amount of rainfall determines the levels of dust particles around Sub-Saharan Africa. As the rainfall changes with changing climate, the infant mortality rates could also change, they wrote. Changes in rainfall in the region could lead to a 13 percent reduction or even a 12 percent increase in infant mortality rates, the researchers calculated. As more significant changes in climate occur, health impacts on the African population could be more significant, they concluded.

As a suggestion, the researchers said that dampening sand using groundwater in the Bodélé region could stop the dust from rising and polluting the air. This has been successfully tried in California, they wrote. Solar-powered irrigation systems costing only $24 per person, for example, could help prevent 37,000 infant deaths per year in West Africa, they calculated.

Study author Sam Heft-Neal, a research scholar at Stanford's Center on Food Security and the Environment, said, "Standard policy instruments can't be counted on to reduce all forms of air pollution. While our calculation doesn't consider logistical constraints to project deployment, it highlights the possibility of a solution that targets natural pollution sources and yields enormous benefits at a modest cost."