Assessing low-cost sensor for characterizing temporal variation of PM2.5 in Bandung, Indonesia

Fine particulate matter (PM_2.5) is a concern due to its health effects, necessitating critical monitoring for both quantity and variability. Utilizing low-cost sensors to track PM_2.5 is essential to augment other monitoring instruments, which are effective in generating temporal and spatial data. Therefore, in this study, we employed the low-cost PurpleAir (low-cost PA-II) to characterize the seasonal and diurnal variation of PM_2.5 in Bandung, Indonesia, representing the densely populated metropolitan area of Bandung. During the sampling period from June 2022 to May 2023, co-location sampling with the filter-based Super Speciation Air Sampling System (SuperSASS) was employed to assess the low-cost PA-II. The PM_2.5 data collected by the low-cost PA-II were compared to the SuperSASS data. The annual average mass concentration of PM_2.5 measured by SuperSASS and the low-cost sensor was 31.51 ± 15.53 μg/m³ and 39.04 ± 15.16 μg/m³, respectively, surpassing the Indonesian government's regulation limit for an annual average of 15 μg/m³. The comparative results of the two methods were obtained with R² = 0.96, and low-cost PA-II data was 1.24 higher than SuperSASS. The difference may be attributed to several factors, including differences in sensor technology, calibration, location, and data processing. The seasonal variation indicated an increase in concentration during the dry season and a decrease during the wet season. The diurnal pattern indicates the morning peak between 06:00 and 08:00 during the rush hour, as well as the evening peak between 18:00 and 23:00, attributed to low temperatures and stagnant conditions. The diurnal pattern of PM_2.5, which often exhibits the lowest peak at midday, is influenced by a combination of meteorological, atmospheric, and human activity factors. The findings suggested that the utilization of low-cost PA-II for a broader spatial scope is promising for real-time monitoring of PM_2.5, to increase air pollution awareness in society.