Exposure to air pollution during childhood significantly increases the risk of developing bronchitis in adulthood, according to a new study published on June 28 in the American Journal of Respiratory and Clinical Care Medicine.

The research, conducted by Dr. Erika Garcia and colleagues from the University of Southern California Keck School of Medicine, found that young adults with bronchitis symptoms were more likely to have been exposed to certain air pollutants as children. The study highlighted two primary types of air pollution: particle pollution (from sources such as dust, pollen, wildfire ash, industrial emissions, and vehicle exhaust) and nitrogen dioxide (primarily from gasoline engines).

Bronchitis is characterised by inflammation of the large airways in the lungs, leading to severe coughing spells that produce mucus or phlegm, wheezing, chest pain, and shortness of breath.

“Our results suggest that childhood air pollution exposure has more subtle effects on our respiratory system that still impact us in adulthood,” said Dr. Garcia. “Reducing air pollution would have benefits not only for current asthma in children but also for their respiratory health as they grow into adulthood.”

While the association between air pollution and childhood lung ailments is well documented, this study is among the few that examines the long-term impact of childhood exposure on adult lung health, irrespective of whether the children had pre-existing lung problems.

Children are especially vulnerable to air pollution because their respiratory and immune systems are still developing, and they inhale more air relative to their body mass compared to adults.

The study analysed data from over 1,300 young adults who had participated in a long-term children’s health study. Researchers found that a quarter of these participants had experienced bronchitis symptoms in the past 12 months. They tracked the participants' residential history and matched it with local air quality data collected by the Environmental Protection Agency (EPA).

The findings revealed a significant link between childhood air pollution exposure and adult bronchitis, even after accounting for any childhood asthma or bronchitis. The association was even stronger for those who had been diagnosed with asthma as children, indicating that some individuals may be more sensitive to the effects of air pollution.

“We may want to be especially careful to protect them from exposure, so we can improve their outcomes later in life,” Garcia said.

Notably, the study found that participants with adult bronchitis had been exposed to nitrogen dioxide levels in childhood that were well below the current EPA annual standards, set in 1971. This suggests that even relatively low levels of pollution can have long-term health effects.

“This study highlights the importance of lowering air pollution, especially exposure during the critical period of childhood,” Garcia emphasised. “Because there’s only so much that we can do as individuals to control our exposure, the need to protect children from the adverse effects of air pollution is better addressed at the policy level.”

The study underscores the importance of robust environmental policies aimed at reducing air pollution to protect public health, particularly the health of vulnerable children, whose early exposure can have lasting consequences.