Prenatal Household Air Pollution Exposure Linked to Pneumonia Risk in Infants

pregnant woman sleeping
The study found prenatal exposure to carbon monoxide in household air pollution was a risk factor for early pneumonia, a leading global cause of death for children younger than 5 years.

Eliminating prenatal exposure to household air pollution, particularly carbon monoxide (CO), may help reduce the risk of pneumonia in infants, according to study results published in Chest.

Previous studies have suggested that prenatal and postnatal exposure to ambient air pollution and tobacco impair lung health in infants, increasing their risk for lower respiratory infections. In the present study, investigators for the Ghana Randomized Air Pollution and Healthy Study ( Identifier: NCT01335490) noted previous findings that prenatal household air pollution could impair lung function in infants, potentially increasing their risk of developing pneumonia.

In the current study, investigators assessed the association between pneumonia and prenatal and postnatal exposure to household air pollution — particularly CO — in the first year of life. They also measured whether such exposures resulted in variations in acute lower respiratory infection between male and female infants.

The study enrolled 1414 pregnant women who had 1306 (92.4%) live births at more than 28 weeks gestation. Of those infants, 1141 (87%) with at least 1 valid exposure assessment were included in the study. Boys accounted for 51% of the infants. Mothers had an average age of 27.7 years, averaged 1.9 years of education, and had a household size of about 6.7 people.

Physician-diagnosed pneumonia events were reported in 381 infants in the first year of life, with 247 infants having 1 event, 55 infants having 2 events, and 8 having 3 events. There were 111 cases of severe pneumonia, with 99 children having 1 event and 6 children having 2 events. Although pneumonia events occurred more frequently in boys, severe pneumonia was evenly distributed by sex.

Prenatal CO exposure was linked to an increased risk of physician-diagnosed pneumonia (relative risk [RR], 1.10) and severe pneumonia (RR, 1.14) in the first year of life per 1 ppm increase in CO.

In a sex-stratified analysis, girls were found to be more vulnerable to effects of prenatal and postnatal CO exposure compared with boys. For female infants, a 1 ppm increase in prenatal CO was associated with an increased risk for physician-diagnosed pneumonia (RR, 1.20) and severe pneumonia (RR, 1.23). Results for postnatal exposure in girls were similar for severe pneumonia (RR, 1.15), following adjustments.

The average prenatal maternal CO and postnatal child CO exposures were 1.3 parts per million (ppm) and 0.9 ppm, respectively. Fine particulate matter (PM2.5) measures in a subset of participants revealed that the average prenatal (n=662) and postnatal (n=614) maternal PM2.5 exposures were 85.1 μg/m3 and 68.3 μg/m3, respectively.

“As highlighted by our results, mitigating [household air pollution] exposures beginning in the prenatal period may reduce risk for early childhood pneumonia with implications for childhood mortality and morbidity and lifelong health,” the authors noted. “Implementation of a clean air intervention that produces consistent reductions in air pollution exposures may have the greatest effect when begun in pregnancy,” concluded the investigators.


Kinney PL, Asante KP, Lee AG, et al. Pre- and postnatal household air pollution exposures and pneumonia risk: evidence from GRAPHS. Chest. Published online July 20, 2021. doi:10.1016/j.chest.2021.06.080