Legionnaires’ disease in dental offices: quantifying aerosol risks to dental workers and patients

Published on 01/11/2022 | by Waterline Admin

Hamilton KA, Kuppravalli A, Heida A, Joshi S, Haas CN, Verhougstraete M, Gerrity D.

J Occup Environ Hyg. 2021 Jun 23:1-21. doi: 10.1080/15459624.2021.1939878. Epub ahead of print. PMID: 34161202.



  • 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.



Product & Service Spotlight

Introducing B & V Chemicals' new film forming amines for closed circuits and steam boilers.

Product Launch: Film forming amines.

This all-in-one solution offers low-dose, cost-effective treatment. Improves heat transfer efficiency by removing corrosion deposits, leading to cleaner surfaces. Enhances energy and resource efficiency by reducing Total Dissolved Solids (TDS). The stable film provided by polyamines ensures superior corrosion control, promoting longer equipment lifespan.

Plus - environmentally friendly, offering a greener alternative to traditional treatments.

Contact us on ownlabel@bvwater.co.uk for further information.

How the NEW SolidTek® Biocide Feeder Package will BENEFIT YOU

SolidTek® has launched its NEW Biocide Feeder which is functional, compact, and environmentally-friendly.

Designed for use with SolidTek’s® enhanced bromine biocide, BromTek, it offers multiple benefits:

Reduced exposure to fumes and bromine dust (non-pressurised system).

Use with field proven mixed hydantoin biocide - better performance than standard bromine tablets.

Wall mounted reducing footprint of installation.

Charge with product in under 5 minutes without isolation from the system.

Product calculators and tech support available.

Lovibond MD640 Photometer (PTSA & Fluorescein capable)

Product Spotlight Drop Test Kits

How many times have you heard … ‘we’re not sure what the system volume is’. A common problem which can be expensive - wasting chemical over dosing, or underdosing so the treatment is ineffective (i.e. shock dosing a biocide). The MD640 photometer has PTSA & Fluorescein capability built in. Simply use our System Checkers to add to an unknown system and read a PTSA or Fluorescein levels to accurately identify the system volume.

The Hydrosense PRO range


The Hydrosense PRO range pioneers Legionella pneumophila detection, the cause of over 97% of Legionnaires’ disease outbreaks, by identifying all the serogroups 1-15 of this dangerous Legionella species. This easy-to-use, highly sensitive test uses unique filtration, offering a three-line test result that distinguishes between serogroup 1 and serogroups 2-15 within 25 minutes. The water test has a level of detection of 100 CFU/L and swab tests detect 200 CFU per swabbed area, providing crucial, rapid insights for water safety management.