Reference: Trasande L, Malecha P, Attina TM. 2016. Particulate matter exposure and preterm birth: estimates of U.S. attributable burden and economic costs. Environ Health Perspect 124:1913–1918; https://doi.org/10.1289/ehp.1510810
We like to imagine that newborn children come into the world as blank slates—unburdened and capable of achieving anything. Unfortunately, we know that maternal exposures to environmental toxins can affect a growing fetus and contribute to adverse birth outcomes. New analyses out of New York University illustrate the impact of air pollution on premature births and help us understand the ripple effect that has not only on the child, but on society as a whole.
What are the health impacts of premature birth?
Preterm birth, or when a child is born before the 37th week of gestation, is the number 1 cause of death for babies in the U.S. When children are born prematurely, they are more likely to suffer from both short-term (e.g. breathing and feeding difficulties) and longer-term complications. As the brain is the last major organ to mature in human development, premature babies can suffer from long-term cognitive problems like cerebral palsy, social and behavioral issues, and learning disabilities, as well as an increased risk of high blood pressure and diabetes later in life. These problems contribute a measurable economic burden on medical, educational, and social service interventions.
Air pollution exposure is a risk factor for premature birth
There are many known risk factors for premature birth, but most of them—like maternal age, race, and socioeconomic status—are not easily modified or avoided. Environmental risk factors, however, present us with an opportunity to change policies and industrial practices with the aim of reducing exposure to the offending pollutants.
One such environmental risk factor is outdoor air pollution; specifically, the mixture of air pollutants named for their small size: particulate matter 2.5 micrometers in diameter or less (PM2.5). For reference, the diameter of the average human hair is around 50 micrometers. These small particles come from burning fuels, as in vehicle engines, wildfires, and power generation. When inhaled, their tiny size allows them to lodge in the lungs or even enter the blood stream. We are still learning about the health impacts of these particles in our bodies, but studies in laboratories have shown different ways that PM2.5 could be connected to premature birth. For example, these particles may cause inflammation in the developing baby or disrupt the placenta.
Dr. Leonardo Trasande and his colleagues sought to estimate the quantity of premature births and economic costs that could be attributed to PM2.5. The team was specifically interested in understanding how human-generated pollutants impact premature births, so they looked at PM2.5 levels above a threshold of naturally-occurring air pollution from sources like dust storms and wildfires.
Using data to estimate the impact of air pollution on premature births and the economy
Using 2008 U.S. Environmental Protection Agency (EPA) data on daily averages of PM2.5 across all ZIP codes in the contiguous 48 states, the researchers estimated exposure for each county. They then used an estimate of risk produced by combining a number of other studies that researched the impact of PM2.5 exposure on preterm birth. The risk estimate describes how much more likely a woman is to deliver prematurely after exposure to a given amount of PM2.5 over the course of her pregnancy. Using statistics, the researchers could then approximate the impact of PM2.5 exposure on pre-term births across the country in 2008. The direct health care costs of preterm birth were obtained from an Institute of Medicine report, and longer-term impacts on economic productivity were estimated using a number of previously-published studies.
What did the study find?
Taken all together, the data suggest that 3.32% of all preterm births (or 15,808 births) in the period of study were attributable to PM2.5 exposure, and that these preterm births cost $760 million in direct medical care, plus $4.33 billion in lost economic productivity over the life of the child.
This study is limited by its reliance on models, which are only as good as their inputs. For one, the EPA air pollution monitors only measure air pollution at a single location, whereas people move around and can be exposed to a variety of conditions. Also, as human beings are complex and capable of overcoming adversity, it is a challenge to precisely equate cognitive delays with reduced earning potential.
A takeaway message
These findings suggest that PM2.5 contributes significantly to the number of preterm births in the U.S., and that air pollution has a measurable impact on the economy. These results are particularly interesting when one considers that a key reason for political resistance to measures aimed at reducing outdoor air pollution is fear that emissions-control strategies will harm economic productivity! Dr. Trasande and his team hope that politicians will be able to use these economic impact estimates to help inform their decision-making processes when considering regulatory strategies for reducing air pollution emissions.
Interested in the current PM2.5 levels in your area? Check https://airnow.gov