Assessment of Fine (PM 2.5) Concentration from Incense Burning in the Residential Homes of Thimphu City: A Scoping Study in Bhutan

Incense burning is an indispensable ritualistic practice deeply embedded in Asian countries. The particulate matter (PM) concentration from incense burning is carefully examined in other countries, however, Bhutan lacks research studies on indoor air quality (IAQ) primarily resulting from incense burning in different indoor environments. Under future climate scenarios, assessing the IAQ is essential to mitigate the health effects of climate change. In this study, the mean concentration of PM2.5 and PM10 is determined to examine the impact of incense burning on IAQ in the ten residential homes of Thimphu City. For measurement purposes, the Laser egg was used to collect the data for 24 h in each home. The mean concentration of PM2.5 and PM10 in the entire household was 102.3 ± 76.5 µg/m3 and 110.1 ± 79.9 µg/m3 respectively. All the ten monitored homes exceeded the World Health Organization (WHO) air quality threshold of 15 µg/m3 and 45 µg/m3 of PM2.5 and PM10 respectively over 24 h. Our results indicated that the mean concentration of PM2.5 exceeded 6.8 times the WHO threshold. The highest concentration of PM2.5 was found in home 10, where the windows and doors were closed during the entire monitoring period. The quantification of PM2.5 elucidated that the status of IAQ in Bhutan is poor especially due to the burning of incense as it exceeded the PM concentration resulting from cooking and smoking activities. However, the exposure to the harmful pollutants can be reduced through open ventilation during incense burning. On a contrary, the recommendation for open ventilation loses its appeal under the future climate changes in Bhutan. Hence, keeping this study as the scoping evidence, it opens for further investigation into elucidating the nexus between improved IAQ and its associated health benefits within the context of changing climatic conditions.