The Center for Disease Control (CDC) has provided guidance on droplet precaution that might need to be reconsidered. In the cloud: How coughs and sneezes float farther than you think is a study that uncovers the way coughs and sneezes stay airborne for long distances. Discussed at MIT News, the study specifically “finds that droplets 100 micrometers — or millionths of a meter — in diameter travel five times farther than previously estimated, while droplets 10 micrometers in diameter travel 200 times farther. Droplets less than 50 micrometers in size can frequently remain airborne long enough to reach ceiling ventilation units.” The video at this link shows droplets moving 6-8 meters (20-26 feet), considerably farther than the 6 foot droplet precaution put forth by CDC.
Extensive Viable Middle East Respiratory Syndrome (MERS) Coronavirus Contamination in Air and Surrounding Environment in MERS Outbreak Units explored the possible contribution of contaminated hospital air and surfaces to MERS transmission by collecting air and swabbing environmental surfaces in 2 hospitals treating MERS-CoV patients. The study shows clearly droplet precaution isn’t working. The presence of MERS-CoV was confirmed by reverse transcription polymerase chain reaction (RT-PCR) of viral cultures of 4 of 7 air samples from 2 patients’ rooms, 1 patient’s restroom, and 1 common corridor. In addition, MERS-CoV was detected in 15 of 68 surface swabs by viral cultures. Immunofluorescence assay (IFA) on the cultures of the air and swab samples revealed the presence of MERS-CoV. EM images also revealed intact particles of MERS-CoV in viral cultures of the air and swab samples. The study concludes: These data provide experimental evidence for extensive viable MERS-CoV contamination of the air and surrounding materials in MERS outbreak units. Thus, our findings call for epidemiologic investigation of the possible scenarios for contact and airborne transmission, and raise concern regarding the adequacy of current infection control procedures.
- In June 2009 American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) published its findings about airborne transmission of disease: ASHRAE Position Document on Airborne Infectious Diseases.