Impact of ventilation systems at different pressures on laboratory contamination during the extraction of COVID-19 RNA
OBJECTIVE To investigate the impact of ventilation systems at different pressures on laboratory con-taimination during the extraction of COVID-19 RNA.METHODS The novel coronavirus nucleic acids were extrac-ted in a polymerase chain reaction(PCR)laboratory with the ventilation system turned on and off under negative pressure,and the contamination of air and laboratory surfaces was examined to identify areas of operational risk.This experiment was divided into two parts,one part was a real scenario test,and the other part was an aerosol generator simulation experiment accidental spraying experiment.RESULTS Real scenario test:negative pressure was turned on,air sampling in room Ⅰ for respiratory syncytial pseudovirus(RSV),and novel coronavirus(2019-nCoV)were negative,and influenza A and influenza B pseudoviruses(H1N1 subtype)(ABH1)appeared positive in the doorway sam-pling after UV irradiation;air sampling in room Ⅱ for ABH1 results were negative,and RSV appeared positive at the re-frigerator.2019-nCoV were positive during the operation,positive results were detected only at the refrigerator after UV irradiation,and no positive results were found after disinfection.In the wipe sampling,there were more contaminations in both room Ⅰ and Ⅱ using ABH1,RSV,2019-nCoV solution during the operation and after UV irradiation,and the results all changed from positive to negative or the Ct value became larger after sterilization;the negative pressure was turned off,the window sampling appeared positive in the air air sampling of RSV reaction solution during the operation in roomⅠ;the wipe sampling appeared positive at the refrigerator and the door knob,the transfer cabinet handles,and the table.Air sampling in the ABH1 reaction solution during the operation in room Ⅱ were positive,and air sampling in the refriger-ator remained positive after UV disinfection.Wipe sampling in room Ⅱ appeared positive in all except table 1,and door handle,refrigerator handle,and surface of the biosafety cabinet remained positive after disinfection.Aerosol simulated ac-cidental spattering test:no positive results were observed when negative pressure was turned on and off in laboratory Ⅱ.CONCLUSION Non-negative pressure conditions presented more points than negative pressure conditions,indica-ting that negative pressure might play a role in the prevention and control of biological safety cabinet experiments;the experimenter's gloves as the source of dissemination of contamination was more common in the experimental proces.Operation and use of biological safety cabinets should be standardised,and its own anti-pollution system and ultraviolet elimination system could prevent contamination;the laboratory should be properly sterilized as well as cleaned to prevent laboratory contamination.
Laboratory safetyLaboratory contaminationCOVID-19Negative pressureExtraction period of RNAPolymerase chain reaction laboratory ventilation system
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