Peaks, sources, and immediate health impacts of PM2.5 and PM1 exposure in Indonesia and Taiwan with microsensors.

Background: Microsensors have been used for the high-resolution particulate matter (PM) monitoring.

Objectives: This study applies PM and health microsensors with the objective of assessing the peak exposure, sources, and immediate health impacts of PM_2.5 and PM₁ in two Asian countries.

Methods: Exposure assessment and health evaluation were carried out for 50 subjects in 2018 and 2019 in Bandung, Indonesia and for 55 subjects in 2019 and 2020 in Kaohsiung, Taiwan. Calibrated AS-LUNG sets and medical-certified RootiRx® sensors were used to assess PM and heart-rate variability (HRV), respectively.

Results: Overall, the 5-min mean exposure of PM_2.5 and PM₁ was 30.4 ± 20.0 and 27.0 ± 15.7 µg/m³ in Indonesia and 14.9 ± 11.2 and 13.9 ± 9.8 µg/m³ in Taiwan, respectively. The maximum 5-min peak PM_2.5 and PM₁ exposures were 473.6 and 154.0 µg/m³ in Indonesia and 467.4 and 217.7 µg/m³ in Taiwan, respectively. Community factories and mosquito coil burning are the two most important exposure sources, resulting in, on average, 4.73 and 5.82 µg/m³ higher PM_2.5 exposure increments for Indonesian subjects and 10.1 and 9.82 µg/m³ higher PM_2.5 exposure for Taiwanese subjects compared to non-exposure periods, respectively. Moreover, agricultural waste burning and incense burning were another two important exposure sources, but only in Taiwan. Furthermore, 5-min PM_2.5 and PM₁ exposure had statistically significantly immediate impacts on the HRV indices and heart rates of all subjects in Taiwan and the scooter subjects in Indonesia with generalized additive mixed models. The HRV change for a 10 µg/m³ increase in PM_2.5 and PM₁ ranged from -0.9% to -2.5% except for ratio of low-high frequency, with greater impacts associated with PM₁ than PM_2.5 in both countries.

Impact statement: This work highlights the ability of microsensors to capture high peaks of PM_2.5 and PM₁, to identify exposure sources through the integration of activity records, and to assess immediate changes in heart rate variability for a panel of approximately 50 subjects in Indonesia and Taiwan. This study stands out as one of the few to demonstrate the immediate health impacts of peak PM, complementing to the short-term (days or weeks) or long-term effects (months or longer) assessed in most epidemiological studies. The technology/methodology employed offer great potential for researchers in the resource-limited countries with high PM_2.5 and PM₁ levels.