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? u Recent events: People feel vulnerable –Attack of 9/11 –Anthrax attacks –SARS u What can people do to protect themselves? u Authorities say: Use duct tape, plastic sheets

What Can You Do? u Many potential threats –Terrorist attacks seem unlikely but get attention –Fires at home kill /yr from smoke –Concern about SARS u Most people don’t have a respirator u Could something else be used…

Objectives of This Study u Evaluate makeshift measures for respiratory protection –Readily available at home or office u Evaluate masks and respirators commercially available –Collection efficiency for respirable particles –Pressure drop (resistance to breathing )

Protective Measures Evaluated u Makeshift four household items u Dust Mask three commercially available masks u N95 NIOSH Certified Respirator three commercially available respirators

Makeshift Measures: u Handkerchief –Folded three times; eight layers thick u Bath Towel –Folded twice; four layers thick u T-shirt –Folded twice; four layers thick u Paper Towels –Full roll; half roll Wet and Dry

Paper Towels u Need mouthpiece, plug, perforated roll u Breathe through mouth only u Face seal unnecessary Anyone can use

Dust Masks u Package: –“use only for sweeping, mowing, pollen relief” –“use for comfort and breathing relief from cold air, non-toxic dusts, pollen, cut grass” u Cost about $0.40 u Readily available No Warning on Mask

N95 Respirators u Package: –“helps protect against certain particles” –“misuse may result in sickness or death” –“meets OSHA recommendation for protection against SARS” u Cost about $1.75 u Available, if you look Warning on Mask

Procedure Rotameter 40 LPM Total Aerosizer DMP Flow Divider Room Aerosol Mask Room Aerosol Mask Five Replicate Tests 1 - Mask, No Mask; 2 - No Mask, Mask; 3 - Mask, No Mask; 4 - No Mask, Mask; 5 - Mask, No Mask

Perfect Sealing u Edges taped –Best possible seal –No air flow bypass u Best possible efficiency

Makeshift Respirator Performance Dry 4 0.4

Full Towel Roll – Effect of Air Flow 4 0.4

Half Towel Roll – Effect of Air Flow 4 0.4

Bath Towel – Wet is Worse 4 0.4

T-Shirt – Wet is Worse 4 0.4

Handkerchief – Wet is Worse 4 0.4

Dust Masks are Ineffective 4 0.4

N95 Respirators are Good 4 0.4

Pressure Drop is Low u Ranged from 0.01 to 1.90 inches of water  Wet  P > Dry  P u No difficulty breathing through any of the devices

Other Issues for Paper Towels u How does the cardboard roll get perforated? –Manufacturers could do it –Simple punch could be made u What about pollutant gases? –What is adsorptive capacity for paper towels? u Would toilet paper work as well?

Conclusions u Dust Masks offer Little Protection –Low efficiency for respirable particles u Makeshift Measures offer Some Protection –Bath towel and T-shirt better than handkerchief –Wetting fabrics decreased performance

Conclusions, cont’d u N95 Respirators worked Best –All had efficiencies above 80% for 0.2 < d < 4  m –Edges taped; best possible performance u 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?