Reducing Ambient Particles Related to Pulmonary Function Testing in COVID-19 Pandemic

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Ambient particles related to pulmonary function tests (PFTs) can be reduced in laboratories with moderate aggressive ventilation exchanges, suggesting PFTs can be safely conducted during the COVID-19 pandemic.

Reductions in ambient particles related to pulmonary function tests (PFTs) can be achieved in laboratories with moderately aggressive ventilation exchanges, suggesting PFTs can be safely conducted during the coronavirus disease 2019 (COVID-19) pandemic at most centers as long as additional precautionary measures are taken to reduce virus transmission, according to study results published in CHEST.

The study included 28 adult patients (mean age, 56.7 years) requiring PFTs who tested negative for COVID-19 infection. Patients underwent PFTs across 3 laboratories with air exchange frequencies of 3, 5, and 9 times per hour. Technicians who performed the PFTs wore N95 masks with a face shield or powered air purification respirators during the test.

In addition, all 3 laboratories used a calibrated optical particle sizer placed 60 cm away from the patient’s face. Particle concentrations were monitored during and approximately 30 to 60 minutes after the tests. Investigators calculated clearance time of the particles as well as the duration between test completion and when particle concentrations return to the lowest concentrations.

A total of 19 patients completed PFTs at an average time of 35 minutes. The investigators found a high ambient level before and after PFTs for particles 0.5 μm or smaller in size. A small increment during testing and a decrease after testing was observed but returned to the pre-test ambient level after 25 to 30 minutes. There was an increase in larger particles during testing; larger particles peaked at the end of testing and decreased after testing to their lowest concentration.

Particle concentrations had a high ambient level at the start of testing in the laboratory that had an air exchange frequency of 3 times per hour and larger room size with an additional window air conditioner. The particle size decreased to the lowest level following test completion but was followed by a subsequent increase towards levels recorded prior to the test.

Concentrations of aerosol particles 1 μm or larger were highest when PFTs were performed, and it took approximately 20 minutes for these concentrations to return to their lowest baseline levels after PFTs were completed at the 2 larger laboratories. In contrast, it took between 30 and 50 minutes in the smaller laboratory with air exchange frequency of 5 per hour for particle concentrations to return to their lowest baseline level.

Limitations of this study included the overall small patient sample and number of PFTs performed as well as the limited number of PFT laboratories included.

The researchers of the study emphasized the importance of using personal protective equipment for PFT procedures during the pandemic and suggest “alternative methods including portable electronic spirometry and self-monitoring technologies might be considered.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Li J, Jing G, Fink JB, et al. Airborne particulate concentrations during and after pulmonary function testing. Published online October 31, 2020. CHEST. doi:10.1016/j.chest.2020.10.064