Indoor environment quality in dental clinics: potential concerns from particulate matter

To provide a comprehensive assessment of the indoor environment of a representative dental office.

Health and comfort parameters, including carbon dioxide (CO2), respirable particulate matter (PM2.5), volatile organic compounds (VOCs), temperature, relative humidity, light and sound level, were measured at three sites over a 1-week period. Both real-time and integrated sampling methods were used, and clinic activities were recorded. Measurements were compared to guidelines and standards, and interactions between pollutant levels, emissions, and clinic activities were investigated using correlations, trend analyses, and a ventilation assessment.

Comfort parameters were found to be within recommended values, with the exception of relative humidity, which was low but not unusual for the winter season investigated. Ventilation rates were within accepted guidelines. Integrated sampling showed that concentrations of VOCs were well below guidelines. However, PM2.5 levels exceeded ambient standards (by a factor of 2 to 6) throughout the building. Continuous trending allowed identification of peak levels, but correlations of clinic activities with measured concentrations were inconclusive. The results suggested that levels of air contaminants in dental clinics (with the exception of PM) are within guideline levels. With the recirculating ventilation systems found in most clinics and offices, particulate contaminants may rapidly disperse throughout a building. Improved capture, exhaust and filtration would decrease indoor PM concentrations. If contaminants are pathologic, the ramifications for practitioners may be considerable, and some specialists may be particularly at risk.