Nanoparticle Penetration through Filter Media and Leakage through Face Seal Interface of N95 Filtering Facepiece Respirators

Skip Navigation
Samy Rengasamy1,* and Benjamin C. Eimer2

1Policy and Standard Development Branch, National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, 626 Cochrans Mill Road, PO Box 18070, Pittsburgh, PA 15236, USA

2Policy and Standard Development Branch, URS, Corporation 626 Cochrans Mill Road, PO Box 18070, Pittsburgh, PA 15236, USA ?* Author to whom correspondence should be addressed. Tel: 1-412-386-6853; Fax: 1-412-386-4089; e-mail: ARengasamy{at}cdc.gov Received June 17, 2011. Accepted December 16, 2011. National Institute for Occupational Safety and Health recommends the use of particulate respirators for protection against nanoparticles (<100 data-blogger-escaped-20="20" data-blogger-escaped-400="400" data-blogger-escaped-45="45" data-blogger-escaped-50="50" data-blogger-escaped-8="8" data-blogger-escaped-a="a" data-blogger-escaped-afforded="afforded" data-blogger-escaped-all="all" data-blogger-escaped-although="although" data-blogger-escaped-and="and" data-blogger-escaped-any="any" data-blogger-escaped-artificially="artificially" data-blogger-escaped-as="as" data-blogger-escaped-at="at" data-blogger-escaped-been="been" data-blogger-escaped-better="better" data-blogger-escaped-breathing="breathing" data-blogger-escaped-by="by" data-blogger-escaped-combination="combination" data-blogger-escaped-component="component" data-blogger-escaped-concerning="concerning" data-blogger-escaped-condition="condition" data-blogger-escaped-considered="considered" data-blogger-escaped-documented="documented" data-blogger-escaped-efficiency="efficiency" data-blogger-escaped-expanded="expanded" data-blogger-escaped-extent="extent" data-blogger-escaped-face-to-facepiece="face-to-facepiece" data-blogger-escaped-face="face" data-blogger-escaped-facepiece="facepiece" data-blogger-escaped-filter="filter" data-blogger-escaped-filtering="filtering" data-blogger-escaped-for="for" data-blogger-escaped-four="four" data-blogger-escaped-function="function" data-blogger-escaped-have="have" data-blogger-escaped-higher="higher" data-blogger-escaped-i.e.="i.e." data-blogger-escaped-in="in" data-blogger-escaped-information="information" data-blogger-escaped-interfaces="interfaces" data-blogger-escaped-introduced="introduced" data-blogger-escaped-inward="inward" data-blogger-escaped-is="is" data-blogger-escaped-l="l" data-blogger-escaped-laboratory="laboratory" data-blogger-escaped-lacking.="lacking." data-blogger-escaped-leakage="leakage" data-blogger-escaped-leaks="leaks" data-blogger-escaped-manikin.="manikin." data-blogger-escaped-measure="measure" data-blogger-escaped-measured="measured" data-blogger-escaped-mechanisms="mechanisms" data-blogger-escaped-media="media" data-blogger-escaped-minute="minute" data-blogger-escaped-models.="models." data-blogger-escaped-models="models" data-blogger-escaped-most="most" data-blogger-escaped-mpps="mpps" data-blogger-escaped-n95="n95" data-blogger-escaped-nanoparticle="nanoparticle" data-blogger-escaped-nm="nm" data-blogger-escaped-of="of" data-blogger-escaped-our="our" data-blogger-escaped-particle="particle" data-blogger-escaped-particles.="particles." data-blogger-escaped-particles="particles" data-blogger-escaped-particulate="particulate" data-blogger-escaped-penetrating="penetrating" data-blogger-escaped-penetration="penetration" data-blogger-escaped-previous="previous" data-blogger-escaped-protection="protection" data-blogger-escaped-respirator="respirator" data-blogger-escaped-respirators="respirators" data-blogger-escaped-results="results" data-blogger-escaped-s="s" data-blogger-escaped-seal.="seal." data-blogger-escaped-seal="seal" data-blogger-escaped-sealed="sealed" data-blogger-escaped-showed="showed" data-blogger-escaped-significance="significance" data-blogger-escaped-significantly="significantly" data-blogger-escaped-size="size" data-blogger-escaped-specific="specific" data-blogger-escaped-study="study" data-blogger-escaped-than="than" data-blogger-escaped-that="that" data-blogger-escaped-the="the" data-blogger-escaped-this="this" data-blogger-escaped-through="through" data-blogger-escaped-til="til" data-blogger-escaped-to="to" data-blogger-escaped-total="total" data-blogger-escaped-understand="understand" data-blogger-escaped-using="using" data-blogger-escaped-volumes="volumes" data-blogger-escaped-was="was" data-blogger-escaped-well="well" data-blogger-escaped-with="with"> < 0.05) higher than the values for 400 nm size particles. A consistent increase in filter penetrations for 45 and 400 nm size particles was obtained with increasing breathing minute volumes. Artificial leakage of test aerosols (mode size ~75 nm) through increasing size holes near the sealing area of FFRs showed higher TIL values for 45 nm size particles at different minute volumes, indicating that the induced leakage allows the test aerosols, regardless of particle size, inside the FFR, while filter penetration determines the TIL for different size particles. TIL values obtained for 45 nm size particles were significantly (P

< 0.05) higher than the values obtained for 400 nm size particles for all four models. Models with relatively small filter penetration values showed lower TIL values than the models with higher filter penetrations at smaller leak sizes indicating the dependence of TIL values on filter penetration. When the electrostatic charge was removed, the FFRs showed a shift in the MPPS to ~150 nm with the same test aerosols (mode size ~75 nm) at different hole sizes and breathing minute volumes, confirming the interaction between filter penetration and face seal leakage processes. The shift in the MPPS from 45 to 150 nm for the charge removed filters indicates that mechanical filters may perform better against nanoparticles than electrostatic filters rated for the same filter efficiency. The results suggest that among the different size particles that enter inside the N95 respirators, relatively high concentration of the MPPS particles in the breathing zone of respirators can be expected in workplaces with high concentration of nanoparticles. Overall, the data obtained in the study suggest that good fitting respirators with lower filter penetration values would provide better protection against nanoparticles. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2012This ArticleAnn Occup Hyg (2012) 56 (5): 568-580. doi: 10.1093/annhyg/mer122 First published online: January 31, 2012 Current Issue
Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

View the original article here

Read more »

Evaluation of Filter Media for Particle Number, Surface Area and Mass Penetrations

Skip Navigation
LIN LI1,*, ZHILI ZUO1, DANIEL A. JAPUNTICH2 and DAVID Y.H. PUI1

1 Particle Technology Laboratory, Mechanical Engineering, University of Minnesota, 111 Church Street SE,

Minneapolis, MN 55455, USA

; 2 3M Company Building 201-2E-04,

Saint Paul, MN 55144, USA ? *Author to whom correspondence should be addressed. Tel: +3145182090; e-mail: llin{at}umn.edu Received April 5, 2012. Revision received February 21, 2012. Accepted March 14, 2012. The National Institute for Occupational Safety and Health (NIOSH) developed a standard for respirator certification under 42 CFR Part 84, using a TSI 8130 automated filter tester with photometers. A recent study showed that photometric detection methods may not be sensitive for measuring engineered nanoparticles. Present NIOSH standards for penetration measurement are mass-based; however, the threshold limit value/permissible exposure limit for an engineered nanoparticle worker exposure is not yet clear. There is lack of standardized filter test development for engineered nanoparticles, and development of a simple nanoparticle filter test is indicated. To better understand the filter performance against engineered nanoparticles and correlations among different tests, initial penetration levels of one fiberglass and two electret filter media were measured using a series of polydisperse and monodisperse aerosol test methods at two different laboratories (University of Minnesota Particle Technology Laboratory and 3M Company). Monodisperse aerosol penetrations were measured by a TSI 8160 using NaCl particles from 20 to 300nm. Particle penetration curves and overall penetrations were measured by scanning mobility particle sizer (SMPS), condensation particle counter (CPC), nanoparticle surface area monitor (NSAM), and TSI 8130 at two face velocities and three layer thicknesses. Results showed that reproducible, comparable filtration data were achieved between two laboratories, with proper control of test conditions and calibration procedures. For particle penetration curves, the experimental results of monodisperse testing agreed well with polydisperse SMPS measurements. The most penetrating particle sizes (MPPSs) of electret and fiberglass filter media were ~50 and 160nm, respectively. For overall penetrations, the CPC and NSAM results of polydisperse aerosols were close to the penetration at the corresponding median particle sizes. For each filter type, power–law correlations between the penetrations measured by different instruments show that the NIOSH TSI 8130 test may be used to predict penetrations at the MPPS as well as the CPC and NSAM results with polydisperse aerosols. It is recommended to use dry air (<20 data-blogger-escaped-a="a" data-blogger-escaped-adequate="adequate" data-blogger-escaped-aerosol.="aerosol." data-blogger-escaped-aerosol="aerosol" data-blogger-escaped-air="air" data-blogger-escaped-an="an" data-blogger-escaped-and="and" data-blogger-escaped-as="as" data-blogger-escaped-challenge="challenge" data-blogger-escaped-chloride="chloride" data-blogger-escaped-constant="constant" data-blogger-escaped-cpc="cpc" data-blogger-escaped-deliquescing="deliquescing" data-blogger-escaped-detectors.="detectors." data-blogger-escaped-dielectric="dielectric" data-blogger-escaped-for="for" data-blogger-escaped-fully="fully" data-blogger-escaped-geometric="geometric" data-blogger-escaped-in="in" data-blogger-escaped-is="is" data-blogger-escaped-it="it" data-blogger-escaped-makeup="makeup" data-blogger-escaped-mean="mean" data-blogger-escaped-minimizing="minimizing" data-blogger-escaped-nanoparticle="nanoparticle" data-blogger-escaped-neutralize="neutralize" data-blogger-escaped-neutralizer="neutralizer" data-blogger-escaped-nm="nm" data-blogger-escaped-nsam="nsam" data-blogger-escaped-of="of" data-blogger-escaped-or="or" data-blogger-escaped-particle="particle" data-blogger-escaped-penetration="penetration" data-blogger-escaped-polydisperse="polydisperse" data-blogger-escaped-prevent="prevent" data-blogger-escaped-recommended="recommended" data-blogger-escaped-rh="rh" data-blogger-escaped-simple="simple" data-blogger-escaped-sodium="sodium" data-blogger-escaped-system="system" data-blogger-escaped-test="test" data-blogger-escaped-the="the" data-blogger-escaped-to="to" data-blogger-escaped-use="use" data-blogger-escaped-with="with">Keywords: © The Author 2012. Published by Oxford University Press on behalf of the British Occupational Hygiene SocietyThis ArticleAnn Occup Hyg (2012) 56 (5): 581-594. doi: 10.1093/annhyg/mes034 Current Issue
Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.

View the original article here

Read more »

Social Media Could Boost Condom Use, Study Suggests

THURSDAY, Oct. 11 (HealthDay News) -- Social media can be used to help convince young adults to use condoms to prevent sexually transmitted diseases, a new study finds.

Researchers enrolled online networks of friends who were randomly assigned to an intervention group or a "control" group.

The 942 participants in the intervention group signed up to "like" and receive news from Just/Us, a Facebook community created to promote sexual health. The site featured weekly discussions about topics such as condom use, talking with partners about sexual history, and how to get tested for sexually transmitted diseases. In addition, there were daily updates in the form of video links, quizzes, blogs and discussion threads.

The 636 people in the control group, called 18-24 News, shared general news of interest to 18- to 24-year-olds.

Two months after taking part in the social networking groups, 68 percent of those in the Just/Us group reported using a condom the last time they had sex, compared with 56 percent of those in the 18-24 News group. The rate of condom use during sex in the previous two months was 63 percent in the Just/Us group and 57 percent in the 18-24 News group, the investigators found.

However, the effects seen in the Just/Us group faded over time and there were no differences between the two groups at the six-month follow-up, according to the report published in the November issue of the American Journal of Preventive Medicine.

"The use of social media to influence sexual risk behavior in the short term is novel. It is a first step in considering how to reach the overwhelming numbers of youth online, and how to maximize approaches to technology-based interventions," lead investigator Sheana Bull, of the Colorado School of Public Health's University of Colorado Anschutz Medical Campus, said in a journal news release.

The author of an accompanying commentary, Dr. Nathan Cobb, from the Schroeder Institute for Tobacco Research and Policy Studies at the American Legacy Foundation in Washington D.C., agreed that this use of social media was a step in the right direction. "For health-behavior change intervention designers, Facebook offers something unprecedented -- direct access to an individual's social network, in real time, and without the need for tedious network enumeration by participants," he wrote.

"However, such approaches require multidisciplinary teams that include social media specialists, marketers, and software developers as equal partners in design and intervention development. Building such teams will undoubtedly require changes to traditional funding and development models, but the potential is too large to be ignored or minimized," Cobb added.

-- Robert Preidt Copyright © 2012 HealthDay. All rights reserved. SOURCE: American Journal of Preventive Medicine, news release, Oct. 9, 2012

View the original article here

Read more »