Biomaterial Database

Penetration of airborne microorganisms through a surgical mask and a dust/mist respirator. 1996

K Willeke, and Y Qian, and J Donnelly, and S Grinshpun, and V Ulevicius

Department of Environmental Health, University of Cincinnati, OH 45267-0056, USA.

This study investigated bacterial penetration of different bacterial shapes, aerodynamic sizes, and flow rates through a surgical mask and a dust/mist respirator. The bacterial penetrations were compared with those of spherical corn oil particles of the same aerodynamic diameter tested under the same conditions. The tests were performed at different levels of aerosol penetration. Bacteria, ranging from spherical to rod-shaped with a high aspect (length to width) ratio, were selected as test agents. Among these, Pseudomonas fluorescens physically simulates Mycobacterium tuberculosis by shape and size. The concentrations of bacteria upstream and downstream of the test devices were measured with an aerodynamic size spectrometer. This instrument was found to measure the total viable and nonviable bacterial concentration effectively and dynamically over the entire bacterial size range down to 0.5 microns in aerodynamic size. The results indicate that the spherical corn oil particles and the spherical Streptococcus salivarius bacteria have the same penetration in the size range from 0.9 to 1.7 microns. It has been found that rod-shaped bacteria penetrate less. The penetration difference between the spherical and rod-shaped bacteria depends on the aspect ratio of the bacteria. For an aspect ratio of 4, the penetration of rod-shaped bacteria is about half that of spherical ones. Thus, it is projected that a respirator with 90% efficiency against spherical microorganisms or test particles (10% penetration) will be 95% efficient against rod-shaped microorganisms of the same aerodynamic equivalent diameter with an aspect ratio of 3 to 4, such as Mycobacterium tuberculosis (5% penetration).

UI	MeSH Term	Description	Entries
D008397	Masks	Devices that cover the nose and mouth to maintain aseptic conditions often for the prevention of the spread of infections (e.g. COVID19) or to administer inhaled anesthetics or other gases.	Mask
D009169	Mycobacterium tuberculosis	A species of gram-positive, aerobic bacteria that produces TUBERCULOSIS in humans, other primates, CATTLE; DOGS; and some other animals which have contact with humans. Growth tends to be in serpentine, cordlike masses in which the bacilli show a parallel orientation.	Mycobacterium tuberculosis H37Rv
D010316	Particle Size	Relating to the size of solids.	Particle Sizes,Size, Particle,Sizes, Particle
D011551	Pseudomonas fluorescens	A species of nonpathogenic fluorescent bacteria found in feces, sewage, soil, and water, and which liquefy gelatin.	Bacillus fluorescens,Bacillus fluorescens liquefaciens,Bacterium fluorescens,Liquidomonas fluorescens
D012134	Respiratory Protective Devices	Respirators to protect individuals from breathing air contaminated with harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors.	Gas Masks,Respirators, Air-Purifying,Respirators, Industrial,Industrial Respirators,Air-Purifying Respirator,Air-Purifying Respirators,Device, Respiratory Protective,Devices, Respiratory Protective,Gas Mask,Industrial Respirator,Mask, Gas,Masks, Gas,Protective Device, Respiratory,Protective Devices, Respiratory,Respirator, Air-Purifying,Respirator, Industrial,Respirators, Air Purifying,Respiratory Protective Device
D004391	Dust	Earth or other matter in fine, dry particles. (Random House Unabridged Dictionary, 2d ed)	House Dust,Housedust,Dust, House
D004868	Equipment Failure	Failure of equipment to perform to standard. The failure may be due to defects or improper use.	Defects, Equipment,Device Failure,Failure, Equipment,Malfunction, Equipment,Medical Device Failure,Misuse, Equipment,Device Failure, Medical,Device Failures, Medical,Failure, Medical Device,Failures, Medical Device,Defect, Equipment,Device Failures,Equipment Defect,Equipment Defects,Equipment Failures,Equipment Malfunction,Equipment Malfunctions,Equipment Misuse,Equipment Misuses,Failure, Device,Failures, Device,Failures, Equipment,Malfunctions, Equipment,Misuses, Equipment
D005069	Evaluation Studies as Topic	Works about studies that determine the effectiveness or value of processes, personnel, and equipment, or the material on conducting such studies.	Critique,Evaluation Indexes,Evaluation Methodology,Evaluation Report,Evaluation Research,Methodology, Evaluation,Pre-Post Tests,Qualitative Evaluation,Quantitative Evaluation,Theoretical Effectiveness,Use-Effectiveness,Critiques,Effectiveness, Theoretical,Evaluation Methodologies,Evaluation Reports,Evaluation, Qualitative,Evaluation, Quantitative,Evaluations, Qualitative,Evaluations, Quantitative,Indexes, Evaluation,Methodologies, Evaluation,Pre Post Tests,Pre-Post Test,Qualitative Evaluations,Quantitative Evaluations,Report, Evaluation,Reports, Evaluation,Research, Evaluation,Test, Pre-Post,Tests, Pre-Post,Use Effectiveness
D000336	Aerosols	Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.	Aerosol
D000391	Air Microbiology	The presence of bacteria, viruses, and fungi in the air. This term is not restricted to pathogenic organisms.	Microbiology, Air