Exposure to Household Air Pollution From Biomass Cooking and Severe Pneumonia in Infants
John P McCracken1,2, Eric D McCollum3,4, Kyle Steenland5
1Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens.
Insights
This study found no link between infant exposure to PM2.5 or carbon monoxide (CO) from biomass cooking and severe pneumonia. These findings challenge previous research on household air pollution risks for child respiratory health.
Area of Science:
- Environmental health
- Pediatrics
- Epidemiology
Background:
- Household air pollution from biomass cooking is a suspected risk factor for childhood pneumonia.
- Particulate matter (PM2.5) and carbon monoxide (CO) are key pollutants from biomass fuel combustion.
Purpose of the Study:
- To investigate the longitudinal association between infant exposure to PM2.5 and CO and severe pneumonia.
- To analyze exposure-response relationships in a multi-country cohort.
Main Methods:
- A cohort study of infants (≤12 months) across Guatemala, India, Peru, and Rwanda.
- Measured personal 24-hour exposure to PM2.5 and CO during pregnancy and infancy.
- Modeled the association between pollutant exposure and severe pneumonia cases, adjusted for confounders.
Main Results:
- 3061 infants contributed data; 175 severe pneumonia episodes occurred.
- No significant association was found between prenatal or postnatal PM2.5 exposure and severe pneumonia.
- No association was observed between carbon monoxide exposure and severe pneumonia.
Conclusions:
- This study found no evidence linking infant PM2.5 or CO exposure to severe pneumonia.
- Results suggest that biomass cooking pollution may not be a primary driver of severe infant pneumonia in these settings.
- Findings contrast with prior research and warrant further investigation into pneumonia etiology.
Importance:
Household air pollution from biomass cooking is considered an important risk factor for child pneumonia.
Objective:
To evaluate the longitudinal association between exposure to particulate matter with a diameter of less than or equal to 2.5 µm (PM2.5) or carbon monoxide (CO) and severe pneumonia in infants.
Design, Setting, And Participants:
This cohort study included infants (aged ≤12 months) whose mothers participated in a 4-country randomized clinical trial. Conducted from May 2018 to September 2021, the trial tested whether an 18-month liquefied petroleum gas stove and fuel distribution intervention reduced the incidence of severe pneumonia in offspring during infancy when compared with biomass cooking. The trial was conducted in communities where residents cooked primarily with biomass fuels in Guatemala, India, Peru, and Rwanda. Data analysis was conducted from December 2024 to July 2025.
Exposures:
Twenty-four hour personal exposure to PM2.5 and CO was measured 3 times during pregnancy and 3 times during infancy.
Main Outcome And Measures:
In this exposure-response analysis, severe pneumonia cases were identified using respiratory signs and symptoms with confirmation of consolidation by imaging and hypoxemia by pulse oximetry. The longitudinal association between severe pneumonia in infants and PM2.5 or CO exposures by infant-quarters, adjusted for confounders, was modeled.
Results:
Overall, 3061 infants (48.2% girls; mean [SD] gestational age at birth, 39.3 [1.7] weeks) contributed 11 996 infant-quarters and 13 910 measurements of personal PM2.5 exposures (range, 5.4-1182.0 µg/m3). A total of 175 episodes of severe pneumonia were identified in 160 infants. Those with at least 1 episode of severe pneumonia had similar mean (SD) prenatal (101 [100] µg/m3 vs 88 [80] µg/m3; P = .11) and postnatal (70 [78] µg/m3 vs 67 [93] µg/m3; P = .68) PM2.5 exposures when compared with infants without severe pneumonia. There were no associations between prenatal (adjusted risk ratio [RR], 1.03; 95% CI, 0.94-1.13) or postnatal (adjusted RR, 0.97; 95% CI, 0.87-1.09) PM2.5 exposures and severe pneumonia or between CO exposures and severe pneumonia.
Conclusions And Relevance:
In this cohort study with exposure-response analysis, there was no evidence of an association between longitudinal PM2.5 or CO exposures and severe pneumonia in infants. Taken with the intention-to-treat analysis from the randomized clinical trial, these results challenge prior research suggesting that PM2.5 or CO exposures from biomass cooking are an important risk factor for severe pneumonia in infants.
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