Air pollution is linked to health issues such as stroke, heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataracts. A new study suggests that exposure to air pollution in childhood raises the risk of developing bronchitis later in life.

Researchers from the Keck School of Medicine of USC discovered that childhood exposure to air pollution is linked to lung issues during childhood, which in turn are consistently associated with respiratory problems in adulthood. The results of the study were published in the journal American Journal of Respiratory and Clinical Care Medicine.

"We would expect that these observable impacts on childhood respiratory health would explain the relationship between childhood air pollution exposure and adult respiratory health. Our results suggest that childhood air pollution exposure has more subtle effects on our respiratory system that still impact us in adulthood," corresponding author Erika Garcia said in a news release.

The researchers noted that the link between childhood air pollution exposure and adult bronchitis symptoms persisted even after adjusting for asthma or bronchitis symptoms early in life. The findings stemmed from a comprehensive study that tracked cohorts of Southern Californians from school age through decades into adulthood.

The study involved 1,308 participants from the Children's Health Study. At an average age of 32 during their adult evaluation, the researchers asked about recent bronchitis symptoms such as bronchitis, chronic cough, or congestion with phlegm not associated with a cold. Around 25% of the participants reported experiencing these symptoms within the past year.

They found that bronchitis symptoms were connected to exposure to two types of pollutants from birth to age 17. One type includes fine particles from sources like dust, pollen, wildfire ash, industrial emissions, and vehicle exhaust. The other pollutant, nitrogen dioxide, is produced by vehicle, aircraft, ship, and power plant combustion, and is known to harm lung function.

The researchers note that children are especially susceptible to the effects of air pollution because their respiratory and immune systems are still developing. It is also because they breathe in more air relative to their body mass compared to adults.

"This study highlights the importance of lowering air pollution, especially exposure during the critical period of childhood. 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," Garcia said.