Aerosol generation and mitigation during methacholine bronchoprovocation testing: Infection control implications in the era of covid-19

Yosuf W. Subat, Matthew E. Hainy, Keith D. Torgerud, Pavol Sajgalik, Siva Kamal Guntupalli, Bruce D. Johnson, Kim Chul-Ho, Kaiser G. Lim, Scott A. Helgeson, Paul D. Scanlon, Alexander S. Niven

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Methacholine bronchoprovocation or challenge testing (MCT) is commonly performed to assess airway hyper-responsiveness in the setting of suspected asthma. Nebulization is an aer-osol-generating procedure, but little is known about the risks of MCT in the context of the ongoing coronavirus disease 2019 (COVID-19) pandemic. We aimed to quantify and characterize aerosol generation during MCT by using different delivery methods and to assess the impact of adding a viral filter. METHODS: Seven healthy subjects performed simulated MCT in a near particle-free laboratory space with 4 different nebulizers and with a dosimeter. Two devices continuously sampled the ambient air during the procedure, which detected ultrafine particles, from 0.02–1 lm, and particles of sizes 0.3, 0.5, 1.0, 2.0, 5.0, and 10 mm, respectively. Particle generation was compared among all the devices, with and without viral filter placement. RESULTS: Ultrafine-particle generation during simulated MCT was significant across all the devices. Ultrafine-particle (0.02–1 lm) concentrations decreased 77%–91% with the addition of a viral filter and varied significantly between unfiltered (P <.001) and filtered devices (P <.001). Ultrafine-particle generation was lowest when using the dosimeter with filtered Hudson nebulizer (1,258 6 1,644 particle/mL). Ultrafine-particle concentrations with the filtered nebu-lizer devices using a compressor were higher than particle concentrations detected when using the do-simeter: Monaghan (3,472 6 1,794 particles/mL), PARI (4,403 6 2,948), Hudson (6,320 6 1,787) and AirLife (9,523 6 5,098). CONCLUSIONS: The high particle concentrations generated during MCT pose significant infection control concerns during the COVID-19 pandemic. Particle generation during MCT was significantly reduced by using breath-actuated delivery and a viral filter, which offers an effective mitigation strategy.

Original languageEnglish (US)
Pages (from-to)1858-1865
Number of pages8
JournalRespiratory care
Issue number12
StatePublished - Dec 1 2021


  • Aerosol
  • Asthma
  • COVID-19
  • Droplet
  • Infection Control
  • Methacholine
  • SARS-CoV-2

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


Dive into the research topics of 'Aerosol generation and mitigation during methacholine bronchoprovocation testing: Infection control implications in the era of covid-19'. Together they form a unique fingerprint.

Cite this