Low-cost sensors: Performance test and applications in occupational health studies related to exposure to respirable particles

Particulate matter (PM_2.5), recently classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), represents a major concern for human health, particularly in occupational environments. In response to the need for accessible monitoring tools, this study aimed to: (1) develop a low-cost device for PM_2.5 measurement, (2) evaluate its performance, (3) apply it in real-time workplace monitoring, and (4) Occupational health evaluation considering cancer risk associated with PM_2.5 exposure. The sensing device integrates particulate matter, temperature, and humidity sensors. It is built around a Single Board Computer (SBC) and supports local data storage, GPS compatibility, and Wi-Fi communication. The entire system operates at a total cost of less than USD 500, providing a low-cost yet comprehensive solution for environmental monitoring. Performance testing of the constructed device demonstrated "good" precision (R² = 0.66-0.68), a coefficient of variation between 4.5% and 21.3%, satisfactory accuracy, and a low detection limit. After validation, it was used to measure PM_2.5 concentrations in occupational environments, revealing temporal patterns strongly linked to human activity. The highest average concentrations were recorded during the daytime hours of weekdays (working hours), ranging from 12.25 µg/m³ to 240.19 µg/m³, while nighttime levels were lower (11.22 µg/m³ to 152.08 µg/m³, respectively). The results indicate that local activities are the main contributors to PM_2.5 emissions. On weekends, concentration decreased significantly in all periods, suggesting an overall reduction in line with the suspension of local activities. Occupational health assessed based on cancer risk associated with PM_2.5, assuming 24-hr exposure to the pollutant, showed exposure levels exceeded the annual limits recommended by the WHO and ASHRAE/USEPA across all monitored sites.