Health and Safety Executive A miniature sampler for in-mask workplace measurements: First pilot tests and site visit experiences Peter Stacey, Rhiannon Mogridge, and Alison Bowry peter.stacey@hsl.gsi.gov.uk
Exposure by Mass Concentration Measurement
The miniature respirable particulate sampler
The miniature respirable particulate sampler
Capability Approved for use with selection of FFP 3 masks Samples respirable fraction 4 h in 94 % humidity Performance comparable with the SIMPEDS cyclone Tested on volunteers in laboratory (NaCl aerosol) Does not affect protection factor significantly Peter Stacey, Andrew Thorpe, Rhiannon Mogridge, Taekhee Lee, Martin Harper; A New Miniature Respirable Sampler for In-mask Sampling: Part 1 Particle Size Selection Performance. Ann Occup Hyg 2016; 60 (9): 1072-1083 Rhiannon Mogridge, Peter Stacey, James Forder; A New Miniature Respirable Sampler for In-mask Sampling: Part 2 Tests Performed Inside the Mask. Ann Occup Hyg 2016; 60 (9): 1084-1091
How is the sampler fitted?
Field Tests Purpose To assess the miniature sampler s practical use at the workplace
Field Tests Three (3) sites visited Seven (7) workers and one (1) researcher Ethics Protocol Volunteers Health questionnaire Chief HSE medical officer approval Fit tested on site with HSE supplied FFP3 masks Monitored through sampling
Field test Our Experience Site 1 Inward leakage for iron = 1-24 %
Field Tests Our Experience- Site 2
Field Tests Our Experience Site 3
Field test The Volunteer Experience Comfortable No complaints Can you feel it? one person = occasionally One person = tubing got caught when writing Three people = pumps positioning (preferred the side)
Field Test Our Experience Generally Sampling times = 1 2 h Tubing came off one pump reattached quickly Two people = moisture noted in post sampler tube to pump
Laboratory Tests Mass and Number Concentration Photo credit GRIMM Miniature sampler Respirable Mass < 16 µm 50 % penetration = 4 µm Mini WRAS Mass and number concentration 0.01 34 µm Photo credit Portacount TSI Inc PortaCount Number concentration only About 1 µm and less
Simulated work tasks
Comparison of mini sampler with MiniWRAS in-mask concentration 3500 Gravimetric mass Vs mass from particle size using density Mini sampler dust concentration (ug/m 3 ) 3000 2500 2000 1500 1000 500 MS1 MS2 0 0 500 1000 1500 2000 2500 3000 3500 MiniWRAS Alveolic dust concentration (ug/m 3 )
Aerosol size distribution 10000 1000 Concentration (paeticles/cc) 100 10 1 0.1 0.01 0.001 Challenge In-mask 0.0001 0.00001 35150 25300 18210 13100 9431 6787 4885 3515 2530 1821 1310 943 679 488 352 253 139 72 37 19 10 Particle size (nm)
Leakage by particle size 3 2.5 Inward leakage (%) 2 1.5 1 0.5 0 Particle size (nm)
Messages Initial workplace trials = success Identified practical issues Miniature sampler opportunity to compare mass and number concentration values Some proportion of inward leakage across all sizes up to 35 µm (face seal leakage) Larger sizes = more mass
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