A new study provides new insights into the connection between early exposure to air pollution and lung health later in life. A research team led by the Keck School of Medicine of USC has shown that exposure to air pollution during childhood is directly associated with bronchitis symptoms in adulthood.
To date, much research in the field has established intuitive links that are less direct than that: exposure to air pollution during youth is consistently associated with lung problems during childhood, and childhood lung problems are consistently associated with lung problems in adulthood.
The current study, published in the American Journal of Respiratory Medicine and Clinical CareIt is one of the few studies to show a direct connection between exposure to air pollution in childhood and lung health in adulthood, a connection that is not fully explained by the impacts of air pollution on lung health during childhood. It opens up the possibility that there are factors yet to be understood that explain the trajectory from early exposure to air pollution to respiratory diseases many years later.
The team drew on the USC Children’s Health Study, a large-scale, decades-long study that followed cohorts of Southern California residents from school age and, for many of the participants, into adulthood. adulthood. Importantly, the link between air pollution exposure in childhood and bronchitis symptoms in adulthood persisted even when the researchers adjusted the data to account for asthma or bronchitis symptoms early in life. , a finding that was surprising.
“We would expect these observable impacts on childhood respiratory health to explain the relationship between childhood air pollution exposure and respiratory health in adulthood,” said corresponding author Erika Garcia, PhD, MPH, assistant professor of population and public health sciences at the Keck School of Medicine. “Our results suggest that childhood air pollution exposure has more subtle effects on our respiratory system that still affect us in adulthood.”
Safeguard lung health, now and in the future
The fact that children are particularly vulnerable to the effects of air pollution is partly due to the fact that their respiratory and immune systems are still developing and, compared to adults, they breathe more air relative to their body mass.
Ultimately, the concern is twofold: for the health of today’s youth and for their future health when they grow up. Notably, among study participants who had recent symptoms of bronchitis as adults, average childhood exposure to a pollutant called nitrogen dioxide was well below the Environmental Protection Agency’s annual standards — just over half the limit that was set in 1971 and remains in effect today.
“This study highlights the importance of reducing air pollution, and especially exposure during the critical period of childhood,” Garcia said. “Because there is much we can do as individuals to control our exposure, the need to protect children from the adverse effects of air pollution is best addressed at the policy level.”
The study population consisted of 1,308 participants from the Children’s Health Study with an average age of 32 years at their adult assessment. Researchers asked about recent episodes of bronchitis symptoms (having bronchitis, chronic cough, or congestion or phlegm production not associated with a cold). One-quarter of participants had experienced bronchitis symptoms in the previous 12 months.
The presence of bronchitis symptoms was associated with exposure between birth and age 17 to two types of contaminants. One type groups together small particles in the air such as dust, pollen, wildfire ash, industrial emissions, and vehicle exhaust products. The other, nitrogen dioxide, is a byproduct of combustion in cars, airplanes, ships and power plants that is known to damage lung function.
Long-term health research is vital to drive discovery
To make the analysis as complete as possible, average childhood exposure to pollutants was based on month-by-month estimates. The researchers compared the family home address at each time point to contemporary measurements of local air quality taken by the EPA and through the Children’s Health Study.
“We are fortunate to have this fantastic and nuanced longitudinal study,” Garcia said. “We can learn a lot about how prior experiences impact adult health. This is thanks to a long-term team effort by the participants themselves, their families, the schools they attended, and all of the research staff and researchers who conducted interviews and generated and analyzed data over the years.”
The current study included additional analyses to rule out factors such as prenatal exposure to nitrogen dioxide, current exposure to air pollution in adulthood, and the effects of socioeconomic status in childhood or adulthood as drivers of bronchitis symptoms in adults.
Pollution exposure in young people may harm the lung health of some more than others
Garcia and his colleagues also found that the effect of exposure to nitrogen dioxide and particulate matter during childhood on bronchitis symptoms among adults was stronger in those who had been diagnosed with asthma as children.
“There may be a subpopulation that is more sensitive to the effects of air pollution,” Garcia said. “We may want to take special care to protect them from exposure so that we can improve their outcomes later in life. Reducing air pollution would have benefits not only for current asthma in children but also for their respiratory health as they grow into adulthood.”
She and her colleagues are following up to examine how the level of exposure to air pollution at different ages during youth influences respiratory problems in adulthood. Other future research directions based on the results of the current study could include investigating other markers of childhood and adult respiratory health, such as how well asthma was controlled, or exploring a possible genetic component.
About this study
The study’s co-authors are Zoe Birnhak, Scott West, Steve Howland, Rob McConnell and Shohreh Farzan, Theresa Bastain, Rima Habre and Carrie Breton, all of the Keck School of Medicine; and Frederick Lurmann and Nathan Pavlovic of the environmental consulting firm Sonoma Technology.
This research was supported by the National Institutes of Health (UH3OD023287, P30ES007048).