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

Category: Control Techniques and Strategy

Accepted Manuscripts
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 the aerosol exposure produced by medical nebulizers and the factors affecting the exposure, especially for treatments performed in a patient home environment. Home healthcare workers (HHWs) is a rapidly growing work population often exposed to aerosol hazards. Here, we designed a simulated environment to measure the inhalation aerosol exposure of a HHW administering pressure-nebulized medications. We determined the relative contributions of different factors on the aerosol reduction in the exposure chamber simulating a patient’s bedroom, including room air exchange rate, proximity to the patient, and the patient breathing rate. Additionally, the performance of respiratory protective devices worn by a HHW, a surgical mask and N95 filtering facepiece respirator (FFR), was evaluated with 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 was found to be a factor influencing the aerosol concentration, but the distance effect diminished when it increased beyond 24 inches. For an unprotected HHW, ventilation was the most effective way to reduce the occupational exposure to nebulizer-produced medical aerosols. An increase in air exchange rate from 0 to 5 h-1 significantly reduced the exposure; however, further increase (to 17 h-1) provided only a minor decrease in the particle concentration. Thus, there is no evidence that patient homes need an extremely efficient ventilation to mitigate the HHW’s exposure to the nebulizer-produced medications. Increase in patient breathing flow rate reduced the inhalation aerosol 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 the 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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