https://multimedia.3m.com/mws/media/1792732O/respiratory-protection-faq-healthcare.pdfCan a respirator with a valve be effective against bioaerosols?
The purpose of a respirator’s exhalation valve is to reduce the breathing resistance during exhalation; it does not impact a respirator’s ability to provide respiratory protection. The valve is designed to open during exhalation to allow exhaled air to exit the respirator and then close tightly during inhalation, so inhaled air is not permitted to enter the respirator through the valve.
While a valve does not change a respirator’s ability to help reduce a wearer’s exposure to bioaerosols, it is not recommended that a person who is exhibiting symptoms of illness wear a valved respirator, because there is a possibility that exhaled particles may leave the respirator via the valve and enter the surrounding environment.
In summary:
• Healthcare workers may wear valved or unvalved respirators to help reduce their exposure to potentially infectious aerosols.
• Healthcare workers should wear a surgical respirator (which usually do not have valves) if they require respiratory protection while performing patient care tasks that might generate a high-pressure stream of liquid such as arterial spray.
Does a valved filtering facepiece respirator offer protection to people surrounding the person wearing the respirator if the person wearing the respirator is infected with COVID-19?
Does the valve allow potentially infectious material to escape, such as airborne droplets that may contain virus particles?
Currently 3M is not aware of any studies on the risk of infectious material exhausting out of the exhalation valve of respirators. To date, no guidance has been issued by the CDC, WHO, or NIOSH on this issue.
The above information has been copy and pasted from the 3M link at the top of the page. There is some other info provided in that link which I found informative, some of you may also.
