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Inhalation Exposure and Respiratory Protection of Home Healthcare Workers Administering Aerosolized Medications (Simulation Study)

Category: Control Techniques and Strategy

Volume: 19 | Issue: 5 | Pages: 937-944
DOI: 10.4209/aaqr.2018.10.0366

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Katherine Ollier1, Maija Leppänen1,2, Bingbing Wu1, Michael Yermakov1, Nicholas C. Newman1,3, Tiina Reponen1, Sergey A. Grinshpun 1

  • 1 Center for Health-Related Aerosol Studies, Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, OH 45267-0056, USA
  • 2 On leave from University of Eastern Finland, Department of Environmental and Biological Sciences, 70211 Kuopio, Finland
  • 3 Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA


  • Home healthcare workers (HHWs) are exposed to pressure-nebulized medications.
  • The particle concentration in a HHW’s breathing zone may approach 3 × 105 cm–3.
  • Ventilation, source proximity and the patient breathing affect the aerosol exposure.
  • An N95 respirator is the most potent in reducing the secondhand aerosol exposure.
  • A surgical mask provides a ~20-fold lower exposure reduction than an N95 respirator.


There is little information regarding aerosol exposure from using medical nebulizers and the factors affecting the risk of exposure, especially for treatments performed in a patient’s home environment. Home healthcare workers (HHWs) are a rapidly growing work population often exposed to aerosol hazards. Thus, we designed a simulated environment to measure the aerosol inhalation exposure of an HHW administering pressure-nebulized medications. We determined the relative contributions of different factors to aerosol reduction, namely, the room air exchange rate, proximity to the patient, and patient breathing rate, in an exposure chamber simulating a patient’s bedroom. Additionally, the performance of respiratory protective devices worn by an HHW, a surgical mask and N95 filtering facepiece respirator (FFR), was evaluated using NaCl as a well-established surrogate. The particle concentration in the breathing zone of an unprotected worker ranged from 7,118 to 284,600 cm–3. The proximity to the aerosol source affected the aerosol concentration, but the influence of this factor diminished when the distance increased beyond 24 inches. For an unprotected HHW, ventilation was the most effective way to reduce exposure to nebulizer-produced medical aerosols. An increase in the air exchange rate from 0 to 5 h–1 significantly reduced the exposure; however, a further increase (to 17 h–1) produced only a small reduction in the particle concentration. Therefore, no evidence suggests that patient homes require extremely efficient ventilation to mitigate HHWs’ exposure to nebulizer-produced medications. Increasing the patient’s breathing flow rate reduced the aerosol inhalation exposure; however, this factor cannot be controlled, which weakens its practical viability. Wearing respiratory protection devices was found to be the most efficient way to reduce aerosol exposure (within the set of tested variables). As expected, an N95 FFR with a proper seal was about 20-fold more efficient than a surgical mask.


Aerosol exposure Medical nebulizer Respiratory protection Home healthcare

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