Clearing the Air: Indoor and outdoor PM2.5 exposure in Moderate-Late Preterm Infants

<bold>Introduction:</bold> Air pollution poses a major global environmental health risk. This may in particular apply to preterm infants who are already at increased risk for developing short- and long-term respiratory disease. <bold>Objective:</bold> To assess in- and outdoor PM_2.5 exposure in moderate-late preterm infants. <bold>Methods:</bold> In this observational pilot study, children under the age of two who were born moderately-late preterm were included. Households continuously measured indoor PM_2.5 using an Airthings View Plus for 31 days. Outdoor PM_2.5 concentrations were obtained using the Central Instrument for Air Quality Monitoring model and large-scale concentration maps provided by regional monitoring stations. Hourly averages were used to calculate indoor-to-outdoor (I/O) ratios. Measured concentrations were subsequently examined against WHO air quality guidelines for PM_2.5. <bold>Results:</bold> The study involved 12 households. The median (IQR) indoor PM_2.5 concentration was 11µg/m³ (5-19), outdoor was 14µg/m³ (7-22). In 4 of the 12 households, average I/O-ratio’s surpassed 1 between 17:00 and 20:00. Throughout the measurement period, the WHO-guideline for PM_2.5 of 5µg/m³ was surpassed 94% of time both indoors (range:80-100%) and outdoors (87-97%). 24-Hour average exposure to concentrations of 15µg/m³ or greater occurred for 14 days (4-25) indoors and 18 days (16-20) outdoors respectively. <bold>Conclusion:</bold> Both in- and outdoor PM_2.5 concentrations substantially exceeded WHO air quality standards, posing a significant respiratory health risk for preterm infants. Considerable variability existed in indoor PM_2.5 concentrations among households. Enhanced awareness, understanding, and personalized intervention strategies may improve indoor air quality.