NIOSHTIC-2 Publications Search
A comparison of respirator fit factors determined by portable condensation nuclei counting and forward light-scattering photometric methods.
Rose JC; Oestenstad RK; Rose VE
Appl Occup Environ Hyg 1990 Nov; 5(11):792-797
Respirator fit factors determined by a portable condensation nuclei counter (CNC) and a forward light scattering photometric system were compared. The photometric system was the conventional technique for determining respirator fit factors. The CNC was developed as an alternative since it does not require use of an exposure chamber and test aerosol as does the photometric method. The CNC and the photometer were used to determine fit factors for a 3M Easi-Air silicone half face respirator equipped with high efficiency filters on 24 volunteers. The photometer used a corn-oil aerosol as the test aerosol. During both tests the subjects breathed normally, which was followed by deep breathing, moving their heads side to side and up and down, talking, and finally by normal breathing again. The fit factors measured by the CNC ranged from 61 to 15560, with a geometric mean of 1884 and a geometric standard deviation (GSD) of 3.9. The fit factors obtained by the photometric system ranged from 30 to 52310, geometric mean 2092 and GSD 6.7. Individual fit factors for 14 subjects measured by the photometer were lower than those measured by the CNC. Parametric and nonparametric statistical analysis of the data indicated that the difference between the logarithm of the fit factors and the median difference of the fit factors obtained by the two methods were not significantly different from zero. When fit factors of 100 and 1000 were used as pass/fail criteria the two methods gave good agreement. The authors conclude that on a group basis respirator fit factors obtained by the CNC and the photometric system are very similar.
Respiratory-protective-equipment; Laboratory-testing; Laboratory-techniques; Light-properties; Aerosol-particles; Industrial-hygiene; Statistical-analysis; Health-protection
Issue of Publication
Applied Occupational and Environmental Hygiene
University of Alabama at Birmingham
Page last reviewed: September 11, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division