Negative pressure and aerosol systems for fit testing of respirators on human subjects were compared. Subjects wore small, medium, or large size half mask or full facepiece probed respirators for the conducting of fit tests. By removing the cartridges and installing airtight manifolds in the cartridge receptacles, negative pressure tests were accomplished. Repeated sequential fit tests were conducted on a single subject using both fit test systems. Repeated testing was conducted on three subjects over a 1 month period with both half mask and full face respirators. Sequential fit tests were conducted for 125 military and civilian workers in a respiratory protection program using both negative pressure and aerosol tests. The controlled negative pressure system consistently detected a range of air leakage through fixed leaks and respirator face seals. The aerosol system results were in general an order of magnitude lower than those determined by the negative pressure tests. An assumed inspiratory flow of 431 milliliters/second was used to calculate the negative pressure determined fit factors. Relatively low levels of challenge aerosol were detected in the mask sampling line. The authors suggest that other factors such as leak penetration losses, incomplete mixing due to streamlining, and lung retention may have been important contributors to the reduced aerosol levels detected. The authors conclude that the aerosol fit test systems may seriously underestimate air leakage into respirators.
Links with this icon indicate that you are leaving the CDC website.
The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
You will be subject to the destination website's privacy policy when you follow the link.
CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website.
For more information on CDC's web notification policies, see Website Disclaimers.
CDC.gov Privacy Settings
We take your privacy seriously. You can review and change the way we collect information below.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.
Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.
Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.
Thank you for taking the time to confirm your preferences. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page.