Childhood air pollution linked to bronchitis symptoms in adulthood

Exposure to air pollution in childhood is directly linked to bronchitis symptoms in adulthood, according to findings from a decade-long study in California.

In fact, each standard deviation (SD) increase in average childhood exposure to nitrogen dioxide (NO)2) – a common byproduct of fossil fuel combustion – was associated with a 51% higher risk of cough, phlegm and bronchitis symptoms in adulthood (OR 1.51, 95% CI 1.00-2.27).

and each SD increase in average exposure to particulate matter smaller than 10 μm diameter (PM10) — which can result from pollen, wildfire ash, dust and other sources — was associated with a 69% higher chance of bronchitis symptoms later in life (OR 1.69, 95% CI 1.14-2.49), reported researchers led by Erica Garcia, PhD, MPH, of the Keck School of Medicine at the University of Southern California (USC) in Los Angeles.

These associations remained largely intact even when the researchers adjusted for childhood asthma and bronchitis symptoms, which came as a surprise to the study authors, who detailed their findings in a paper. American Journal of Respiratory and Critical Care Medicine.

“We hope that these direct effects on respiratory health in childhood will explain this connection,” Garcia said in a press release. “Our results suggest that exposure to air pollution in childhood has more subtle effects on our respiratory system, which also affect us in adulthood.”

The authors noted that very few studies have looked at the effects of long-term exposure to air pollution in childhood on adult respiratory health, although research from Norway, Sweden and the Netherlands has demonstrated links between pollution in childhood and asthma in later life. Garcia and co-authors said the current study “contributes to the literature by providing evidence for a pathway from childhood air pollution exposure to adult respiratory outcomes that is unrelated to previous childhood respiratory effects.”

Still, the study found that participants who had asthma in childhood were even more likely to have bronchitis symptoms in adulthood because of their exposure to air pollution:

  • No2: OR 2.27 (95% CI 1.38-3.71) for each SD increase in exposure in childhood
  • time10: OR 2.34 (95% CI 1.39-3.96) for each SD increase

“This study highlights the importance of reducing air pollution, and particularly reducing exposure during the critical period of childhood,” Garcia said. “Since we can only do so much to control our exposure individually, the need to protect children from the adverse effects of air pollution must be better addressed at the policy level.”

It is important to note that the average number of people exposed to nitrogen oxides (NO2) during childhood2 For participants who later reported symptoms of bronchitis as adults, the ratio — 26.8 parts per billion (ppb) — was just over half the annual limit set by the Environmental Protection Agency's standards, which were set in 1971.

Commenting on the study, Elizabeth Gibb, MD, MPhil, of the University of California San Francisco-Benioff Children's Hospitals in Oakland, California, said: MedPage Today Air pollution can cause airway inflammation, decreased mucociliary clearance, and direct injury to the respiratory epithelium.

“This damage to the respiratory tract can lead to remodeling of the airways over time. It's not surprising that these changes to children's airways have long-term effects on their airways as adults,” said Gibb, who was not involved in the research.

Lisa Patel, MD, MESc, of Stanford Medicine Children's Health in Pleasanton, California, who was not involved in the study, emphasized the need to move toward renewable energy and said air pollution counseling should be standard in clinical practice, especially for infants, young children and people with respiratory problems.

“For children who are hospitalized for wheezing, asthma or pneumonia, this is also an important opportunity for counseling,” he added. MedPage Today via email. “I talk to my families about how to read the air quality index, what precautions they should take (like buying an air purifier, or making one themselves if they can't afford one) and the dangers of gas stoves, which produce nitrous oxide and many other pollutants.”

For their study, Garcia and his colleagues relied on data from three cohorts of the decade-long USC Child Health Study, which ultimately included 1,308 participants from 16 communities in Southern California (during the 1990s and early 2000s).

Exposure to air pollution was assessed by inverse-distance-squared spatial interpolation based on residential history during childhood based on patterns recorded for their area. Participants were required to have completed an online survey along with symptoms of bronchitis during adulthood to be included.

Overall, 60% were women and the majority (56%) were non-Hispanic white, with 32% Hispanic and 3% non-Hispanic black.

During childhood, 28% reported mold/mold in the home, 12% reported exposure to smoking in the womb, 13% reported exposure to smoking in the home, 19% had symptoms of bronchitis, 18% had a diagnosis of asthma, and 19% had a parent with asthma. The average pollutant exposure for NO was 26.1 ppb249.1 ppb for O3and 41.9μm/m3 For the Prime Minister10The SDs for each were 11.1 ppb, 10.3 ppb, and 14.2 mg/m3Respectively.

No significant correlation was observed between ozone (O) and oxygen (O).3) pollution and adult bronchitis symptoms, and very few participants had valid estimates of PM2.5 According to the researchers, it was kept in a special laboratory for analysis.

Among the adults evaluated (mean age 32 years), 49% reported having allergies, 18% were smokers, and 25% reported having had symptoms of bronchitis in the past 12 months: most commonly nasal congestion or phlegm (15%), followed by cough throughout the day (8%), cough when waking up in the morning (7%), and having had bronchitis before (7%).

The main analyses adjusted for differences in several factors, including age, income, education, race/ethnicity, smoking or mold/mold in the childhood home, maternal smoking during pregnancy, recent smoking status, and BMI in adulthood.

Limitations noted by Garcia and colleagues included that bronchitis symptoms in adults were recorded at a single time point, leaving room for misclassification; an inability to adjust for current air pollution levels; and limited monitoring of PM2.5.2.5 during the time when the baseline and follow-up questionnaires were conducted.

  • Author['full_name']

    Elizabeth Short is a staff writer for MedPage Today. She frequently covers pulmonology and allergy and immunology. to follow


This study received funding from the NIH and the National Institute of Environmental Health Sciences.

Garcia reported a relationship with the National Institute of Environmental Health Sciences. Co-authors reported a relationship with the NIH ECHO Program and the NIH Office of the Director.

Gibb and Patel have no disclosures.

Main Source

American Journal of Respiratory and Critical Care Medicine

Source Reference: Garcia E, et al “Exposure to air pollution in childhood is associated with self-reported bronchitis symptoms in adulthood” Am J Respir Crit Care Med 2024; DOI: 10.1164/rccm.202308-1484OC.

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