Real-time IAQ assessment inside an Indian temple and evaluation of associated health risks to three different exposure groups through inhalation

The current study, conducted inside a temple in Kanpur City, India, measured indoor air pollution levels (IAQ) and evaluated health risks associated with regular exposure in different groups of visitors. The air quality measurements were conducted on regular and festive days, and samples were analyzed for parameters such as PM, metals, and PAHs. A survey of temple visitors was also carried out to get insights into their frequency of visits to the temple and duration of stay. Submicron particles (PM₁ with d_p≤1 μm) contributed the highest to PM₁₀ on regular and festive days. Particle levels on festive days were higher than on regular days (coarser: PM_{10_max}=971.58 µg/m³ and PM_{1_max}=833.14 µg/m³). Contrarily, particle-bound toxic metals, and carcinogenic PAH concentrations were higher on regular days. We classified three distinct exposure groups of daily visitors based on their duration of stay inside the temple and evaluated the comprehensive health risks for each group. Calculations revealed that the high-exposure group had notably higher particle deposition inside the lungs. The ultrafine particles (d_p<0.1 μm), which penetrate deepest inside the lungs, were the primary carrier (> 50%) of total pPAHs. The high exposure group demonstrated a carcinogenic risk more than 3100 times higher than the baseline risk, whereas, for the low exposure group (duration of visit < 10 min), the risk was more than 85 times than the baseline risk, underscoring the carcinogenic potential and compromised air quality conditions inside the temple. The findings of this study underscore the urgent need to improve the air quality within the temple premises, necessitating immediate actions to address the compromised air quality conditions. We suggest some interventions for the same. We also calculated a safe concentration of carcinogenic species for different exposure groups to provide insight into the extent of air quality management needed for safe exposure levels.