Atmospheric Pollution by Fine Particulate Matter (PM2.5) and Low Birth Weight: A Cross‐Sectional Study in Binza Ozone Health Zone, Democratic Republic of the Congo, 2022
Christian M. Valuvunina, Maurice M. Ngwimi, Joël Nkiama N. Konde, Guillaume M. KiyomboBackground
Air pollution is a major risk factor for perinatal health. PM2.5 can cross the placenta and induce oxidative stress and inflammation, promoting fetal growth restriction and low birth weight (LBW). Sub‐Saharan Africa has the highest PM2.5 exposures in the world, but data on perinatal outcomes there are limited. In the DRC, urbanization and unregulated quarries degrade air quality. The Binza Ozone Health Zone in Kinshasa is home to the Carrigrès quarry within densely populated neighborhoods. No study in the DRC has evaluated the link between PM2.5 exposure and LBW. This study aimed to analyze the association between PM2.5 exposure, proximity to the quarry, and LBW.
Methods
Cross‐sectional study of 355 mothers who delivered between January and December 2021 in six healthcare facilities in Binza Ozone. Data were collected via interviews and reviews of antenatal care (ANC) and delivery registries. LBW was defined as a weight < 2500 g. PM2.5 was measured over 48–72 h per health area in September‐October 2022 using calibrated PurpleAir PA‐II‐SD sensors. The PurpleAir PA‐II‐SD sensor is a low‐cost optical particle counter that was calibrated against the Federal Reference Method (FRM) Beta Attenuation Monitor (BAM) in Kinshasa, as described by McFarlane et al. (2021); the calibration equation applied was as follows: PM2.5 (corrected) = 0.52 × PM2.5(raw)+3.2. Sites were classified as “highly polluted” > 75 μg/m 3 or “polluted” ≤ 75 μg/m 3 based on the median. Distance to the Carrigrès quarry was categorized as < 500 m and ≥ 500 m. Bivariate analysis was performed using the chi‐square test. Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs), adjusted for age, parity, education level, maternal alcohol consumption, tobacco exposure (active and passive smoking), nutritional factors (dietary diversity score and mid‐upper arm circumference), and gestational complications. The significance threshold was set at p < 0.05.
Results
Median age was 26 years (IQR: 20–36). 67.3% had a secondary education level. LBW prevalence: 12.96%, n = 46/355, 95% CI [9.7–16.9]. This prevalence is significantly higher than 7.8% reported for Kinshasa Province in the MICS‐DRC 2017‐2018 survey, confirming the existence of a local aggravating factor. PM2.5 levels ranged from 54.6 to 102.5 μg/m 3 , exceeding both the WHO annual guideline of 5 μg/m 3 and the WHO 24‐h guideline of 15 μg/m 3 . In bivariate analysis, residing < 500 m from the quarry was associated with LBW: 33.3% versus 9.1%, p < 0.001, OR: 4.85 [2.42–9.72]. Gestational complications were also associated: 37.5% versus 10.5%, p < 0.001. PM2.5 > 75 μg/m 3 was not associated: 15.8% versus 11.5%, p = 0.312. In multivariable analysis, proximity < 500 m (aOR: 4.12 [1.98–8.57], p < 0.001) and gestational complications (aOR: 4.67 [2.11–10.34], p < 0.001) remained independently associated with LBW. PM2.5 > 75 μg/m 3 was no longer significantly associated: aOR: 1.18 [0.59–2.36], p = 0.642. Maternal alcohol consumption, tobacco exposure, and nutritional factors were not significantly associated with LBW in this sample ( p > 0.05 for all).
Conclusion
There is a high prevalence of LBW in Binza Ozone compared to the provincial reference of 7.8%, and an independent association with residing < 500 m from a quarry. Very high PM2.5 levels were not independently associated with LBW, suggesting the effect of a mixture of exposures: coarse particles, noise, and socio–economic factors. These results justify urgent interventions: air quality monitoring, buffer zones around quarries, and the integration of environmental risk assessment into prenatal care.