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Effectiveness of Paper Towels as a Makeshift Respirator. David Leith Dept. of Environmental Sciences and Engineering University of North Carolina at Chapel Hill. Is This a Crazy Idea?. Recent events: People feel vulnerable Attack of 9/11 Anthrax attacks SARS
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Effectiveness of Paper Towelsas a Makeshift Respirator David LeithDept. of Environmental Sciences and EngineeringUniversity of North Carolina at Chapel Hill
Is This a Crazy Idea? • Recent events: People feel vulnerable • Attack of 9/11 • Anthrax attacks • SARS • What can people do to protect themselves? • Authorities say: Use duct tape, plastic sheets
What Can You Do? • Many potential threats • Terrorist attacks seem unlikely but get attention • Fires at home kill 2000-3000/yr from smoke • Concern about SARS • Most people don’t have a respirator • Could something else be used…
Objectives of This Study • Evaluate makeshift measuresfor respiratory protection • Readily available at home or office • Evaluate masks and respiratorscommercially available • Collection efficiency for respirable particles • Pressure drop (resistance to breathing )
Protective Measures Evaluated • Makeshift four household items • Dust Mask three commercially available masks • N95 NIOSH Certified Respirator three commercially available respirators
Makeshift Measures: • Handkerchief • Folded three times; eight layers thick • Bath Towel • Folded twice; four layers thick • T-shirt • Folded twice; four layers thick • Paper Towels • Full roll; half roll Wet andDry
Paper Towels • Need mouthpiece,plug, perforated roll • Breathe through mouth only • Face seal unnecessary Anyone can use
No Warning on Mask Dust Masks • Package: • “use only for sweeping, mowing, pollen relief” • “use for comfort and breathing relief from cold air, non-toxic dusts, pollen, cut grass” • Cost about $0.40 • Readily available
Warning on Mask N95 Respirators • Package: • “helps protect against certain particles” • “misuse may result in sickness or death” • “meets OSHA recommendation for protection against SARS” • Cost about $1.75 • Available, if you look
RoomAerosol 40 LPMTotal RoomAerosol RoomAerosol Mask Mask Rotameter Flow Divider Aerosizer DMP Five Replicate Tests 1 - Mask, No Mask;2 - No Mask, Mask;3 - Mask, No Mask;4 - No Mask, Mask;5 - Mask, No Mask Procedure
Perfect Sealing • Edges taped • Best possible seal • No air flow bypass • Best possible efficiency
Makeshift Respirator Performance Dry 4 0.4
T-Shirt – Wet is Worse 0.4 4
N95 Respirators are Good 0.4 4
Pressure Drop is Low • Ranged from 0.01 to 1.90 inches of water • Wet DP > Dry DP • No difficulty breathing through any of the devices
Other Issues for Paper Towels • How does the cardboard roll get perforated? • Manufacturers could do it • Simple punch could be made • What about pollutant gases? • What is adsorptive capacity for paper towels? • Would toilet paper work as well?
Conclusions • Dust Masks offer Little Protection • Low efficiency for respirable particles • Makeshift Measures offer Some Protection • Bath towel and T-shirt better than handkerchief • Wetting fabrics decreased performance
Conclusions, cont’d • N95 Respirators worked Best • All had efficiencies above 80% for 0.2 < d < 4 mm • Edges taped; best possible performance • Paper Towels worked Relatively Well • Need mouthpiece, plug, and perforated tube • No edges to seal • Efficiency similar to N95 respirators • Possible to remove pollutant gases?