PM and ozone in office environments and their potential impact on human health.

It is important to have good indoor air quality, especially in indoor office environments, in order to enhance productivity and maintain good work performance. This study investigated the effects of indoor office activities on particulate matter of less than 2.5 μm (PM) and ozone (O) concentrations, assessing their potential impact on human health. Measurements of indoor PM and O concentrations were taken every 24 h during the working days in five office environments located in a semi-urban area. As a comparison, the outdoor concentrations were derived from the nearest Continuous Air Quality Monitoring Station. The results showed that the average 24 h of indoor and outdoor PM concentrations were 3.24 ± 0.82 μg m and 17.4 ± 3.58 μg m respectively, while for O they were 4.75 ± 4.52 ppb and 21.5 ± 5.22 ppb respectively. During working hours, the range of PM concentrations were 1.00 μg m to 6.10 μg m while for O they were 0.10 ppb to 38.0 ppb. The indoor to outdoor ratio (I/O) for PM and O was <1, thus indicating a low infiltration of outdoor sources. The value of the hazard quotient (HQ) for all sampling buildings was <1 for both chronic and acute exposures, indicating that the non-carcinogenic risks are negligible. Higher total cancer risk (CR) value for outdoors (2.67E-03) was observed compared to indoors (4.95E-04) under chronic exposure while the CR value for acute exposure exceeded 1.0E-04, thus suggesting a carcinogenic PM risk for both the indoor and outdoor environments. The results of this study suggest that office activities, such as printing and photocopying, affect indoor O concentrations while PM concentrations are impacted by indoor-related contributions.