- Dental offices pose a potential risk for inhalation or aspiration of pneumophila due to the high surface area to volume ratio of dental unit water lines (DUWL)
- DUWL are conducive to biofilm growth and high-pressure water devices (e.g., ultrasonic scalers) produce fine aerosols within the breathing zone.
- pneumophila occurs in DUWL, but associated human health risks have not been assessed.
- Probabilities of infection were assessed on a per-exposure and annual basis.
- Following instrument purge (i.e., flush) and with ventilation rate of 1.2 air changes/hr, the median per-exposure probability of infection for dental hygienists and patients exceeded a 1-in-10,000 infection risk benchmark.
- Per-exposure risks for workers during a purge and annual risks for workers wearing N95 masks did not exceed the benchmark.
- Increasing air change rates in the treatment room from 1.2 to 10 would achieve an ∼85% risk reduction, while wearing N95 respirators would reduce risks by ∼95%.
- Concentration of pneumophila in DUWL was a dominant parameter in the model and driver of risk.