Reduced Lung Function Linked to High Levels of Ambient, Household Air Pollution

There is a negative association between ambient particulate matter (PM) and lung function in young adults who recently attained maximum lung function, according to a study published in Environment International. A negative association was also found for household air pollution (HAP) and lung function in young adults, according to the researchers.

Maximum lung function is one of the main determinants of lung function levels and incidence of respiratory disease.

“There are several gaps to be addressed in the association between long-term exposure to air pollution and lung function,” wrote the authors. “Although there is evidence for the association between air pollution and decreased lung function in children, evidence for adolescents and young adults is scarce.”

They noted limited data from low-income countries, minimal research in countries with high ambient air pollution, and few existing studies on air pollution and lung development in adolescents. To better understand these associations, the researchers conducted a cross-sectional, population-based analysis in the third follow-up of the Andhra Pradesh Children and Parent Study cohort (2010-2012). The study is believed to be one of the first evaluating air pollution and lung function of young adults directly following peak lung growth.

Adults aged 20 to 26 years residing in a peri-urban area of South India were studied to estimate the effects of air pollution right after the peak of lung function development. A total of 1044 participants were evaluated. Their mean (SD) age was 22.8 (1) years, and 31% were female.

Forced expiratory volume in the first second (FEV₁) and forced vital capacity (FVC) were measured in the participants and analyzed with the estimated annual average PM having a mean aerodynamic diameter of 2.5 mcm or less (PM_2.5) and self-reported use of biomass cooking fuel (a proxy for levels of household air pollution). The analysis adjusted for factors including sex, health behaviors, and socioeconomic influences.

The researchers observed an association between air pollution and decreased lung function in young adults. Long-term ambient air pollution was associated with decreased FEV₁, although with imprecision.

The study found the mean ambient PM_2.5 exposure to be 32.9 (2.8) mcg/m3, with 76% reporting using biomass as cooking fuel. The adjusted association between 1 mcg/m3 increase in PM_2.5 was –27 mL (95% CI, –89 to 34) for FEV₁ and –5 mL (95% CI, –93 to 76) for FVC. The estimates found for ambient PM_2.5 and FEV₁ were broadly consistent with previous research indicating a negative relationship between PM_2.5 and FEV₁. However, this study observed null associations for ambient PM_2.5 and FVC.

Household air pollution measured by biomass fuel use was consistently associated with decreased FEV₁ and FVC, particularly in those cooking with biomass in unventilated stoves.

The adjusted association between use of biomass fuel was –112 mL (95% CI, –211 to –13) for FEV₁ and –142 mL (95% CI, –285 to 0) for FVC. The adjusted association was of greater magnitude for those with an unvented stove for both FEV₁ (–158 mL; 95% CI, –279 to –36) and FVC (–211 mL; 95% CI, –386 to –36).

Although there has been little research on HAP and lung function in young adults, the estimates of this study are consistent with estimates observed in older adults in other studies.

The authors suggest that chronic inflammation, increased airway resistance, and changes in the lung microbiome are only a few of several pathways that may be involved in the biological mechanism linking ambient PM_2.5 and HAP with lung function. However, they note that it is unclear whether there is a sex-specific effect of air pollution or whether ambient PM is more relevant for FEV₁­­­­­­ vs FVC.

They suggest that reducing levels of exposure to ambient PM_2.5 and HAP might be an effective way to improve lung function in adulthood, encouraging future research.

References

Ranzani OT, Bhogadi S, Mila C, et al. Association of ambient and household air pollution with lung function in young adults in an peri-urban area of South-India: A cross-sectional study. Environ Int. Published online May 11, 2022. doi:10.1016/j.envint.2022.107290.