Aerosol Hazards

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World HealthOrganization

National Institutesof Health

1

Aerosol Hazards

in the Laboratory


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Aerosol Hazards

Objectives

Identify major aerosol-producing activities

List the major factors affecting the ability ofairborne microbes to cause infection

Describe the limitations of workplace

monitoring for aerosols

Describe the effects of the physical

environment on aerosol transport and removal


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Episodes of Single-Source,

Multiple Laboratory Infections

Disease Probable Source

ofInfection

Maximum Distance

From Source

Number

Persons

Infected

Brucellosis Centrif ugation Basement to 3rd floor 94

Coccidioidomycosis Culture transfer solid media 2 Building floors 13

Coxsackie Virus

infection

Spilled tube of infected

mouse tissue on floor

5 feet (estimated) 2

Murine Typhus Intranasal inoculation of mice 6 feet (estimated) 6

Tularemia 20 petri plates dropped 70 feet 5

Venezuelan

encephalitis

9 lyophilized ampoules

dropped

4th floor stairs to 3rdor

5th24

Reitman and Wedum, 1956


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What is an Aerosol?

Particles suspended in a gas

0.5 Q- Q in diameter

In this instance the gas is air


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Approximate

Size Ranges ofVarious

Bioaerosols

Particles Diameters ()

Smoke 0.001 0.1

Viruses 0.015 0.45

Bacteria 0.3 5

Cat Ag-bearing

particles

5)

Fungal spores 2.0 50

Algae cells/clusters 1 100+

Protozoa 2 100+

Dermatophagoides

fecal pellets ~20

Fern spores 20 60

Pollen 1

0 - 100


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Unscrewing Bottle Cap


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Withdrawing Needle from Septum Cap


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Vortex Mixing


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Blowing Out the Last Drop


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Blender Lid Open After Stop


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Aerosols Produced from Laboratory Operations1010 bacteria/ml culture 10 min

Blender, opened at once 106

Sonicator, with bubbling 106

Pipetting, vigorous 10

6

Dropping culture 3 x 105

Splash on centrifuge rotor 105

Drop spill on zonal rotor 2 x 104

Blender, opened at 1 minute 2 x 104

Pipetting, carefully 104

Dimmick et al., 1973


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Aerosol and Surface Recovery from Pipetting

Operations of 109/ml B. subtilis

(average time 3 minutes; 1 ml pipette; ea. 2 ml bulb)Chatigny et al, 1979

RUN Airborne CFUSettled CFU

Hands Area

1 2,040 35,800 3,700

2 657 22,000 860

3 2,050 14,800 1,700

4 388 9,300 550

5 5,110 6,900 2,100

6 649 228,000 2,900

Average 1,820 52,800 1,970


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Aerosols from Animal Cage Cleaning


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Factors Affecting Survival of

Aerosolized Organisms

Environmental temperature, relative

humidity

Suspending Medium pH, specific gravity,

constituents, e.g., protein

Surface porous vs. non-porous


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Factors Affecting Character of

Aerosols

Energy Input

Low Large particles

High Small particles

Infectious Units/Particle

organisms/unit, volume of original

suspension Persistence particle size


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Estimated Small Particle Aerosol Dose

from Pipetting 1010/ml - min

At 3 feet - 1,200 At 10 feet - 50


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Estimated Small Particle Aerosol Dose

from Blender 1010/ml 5 min

At 3 feet - 2,000

At 10 feet - 200

Dimmick 1973 et. al.


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Aerosol Dispersion in a Poorly

Ventilated Room

Dimmick 1973 et. al.


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Summary

Aerosols are generated from most

laboratory tasks

Aerosols can spread through a building

and effect many people

Contamination is often heaviest in work

areas and on worker hands

Documents

Aerosol Hazards