Indoor Air Pollution

Toxins, carcinogens, oh my!

Indoor Air Pollution

• Indoor Air Pollution Trends

• Sources

➡ Carbon Monoxide

➡ Building Materials: Formaldehyde

➡ Mites and Microbes

➡ Radon Gas

➡ Asbestos

➡ Tobacco Smoke

• Regulation and Abatement

Trends

• Concentrations increased during 1980s

➡ Energy-efficient homes leak in less fresh air

➡ Increased use of insulation

➡ Cheaper woodwork

• Exposure time increased

➡ Longer hours spent indoors

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Carbon Monoxide Sources

Building Materials

• Carpets, textiles

➡ Organic solvents, formaldehyde

• Glue in composite materials (plywood, particleboard, plastic laminate)

➡ Formaldehyde, organic vapors

• Paints and coatings

➡ Formaldehyde, organic vapors

• Foams (insulation and cushions)

• Fiber insulation

Formaldehyde

H2CO, CH2O, or HCHO

• Slightly “sweet” odor

• Organic preservative

➡ Preserve biological specimens

➡ Sets dyes

Organic compound

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HCHO in the Home

• Main (long-term) source is furniture, wood, and insulation, not carpets!

➡ Carpets, drapes, paint emit mainly when new

➡ Insulation trapped in walls slowly outgas over a long period

➡ Glues trapped in carpentry outgas slowly over time

HCHO Health Effects

• Effects as concentration/exposure increases (in order):

➡ Eye irritation

➡ Odor detected

➡ Cerebral cortex affected

➡ Nose, throat irritation

➡ Autonomous system affected

• Also carcinogenic

Mites and MicrobesDust mite Dust mite feces

Bacteria VirusesPollen

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Mold• Fungus

➡ “Black mold”: Stachybotrys

• Live or dead cells and spores can cause allergic reactions

Remediation:

1. Eliminate sources of excessive moisture

2. Remove organisms and spores

Infiltration of Outdoor Air Pollutants

• Comes in through open and closed windows, doors

• Seeps in through cracks and gaps in walls and roof

Radon Gas in the Home

• Source: radon gas seeping out of soil

• Radon gas is a decay product of naturally occurring radioisotopes (Uranium-238)

• Radon gas problem increased during the 1980s

➡ Increased awareness

➡ Energy-efficient homes decreased ventilation

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Air

Soil

Uranium-238 Radium-226

Radon-222

Seepage: due to heating/cooling cycle in house

Basement

Polonium-218

Bismuth-214, Lead-214

House

picoCuries per liter

(pCi/l)

4-pack/day smoker100 pCi/l

Radon-infested10 pCi/l

(1 pack/day smoker)

EPA standard4 pCi/l

Radon test kits

Yellow: risk of < 2 pCi/l

Orange: risk of 2–4 pCi/l

Red: risk of > 4 pCi/l

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Radon Mitigation

Blow air into basement

Air pump

Radon Mitigation

Air pump

Layer of coarse gravel

Radon Mitigation

Air pump

Active Subsoil Depressurization

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Asbestos

• A mineral in the form of fibers

• Used extensively as an insulating material

• Problem occurs when fibers break off and become airborne

• Health effects

➡ Asbestosis: chronic inflamation and scarring of lung tissue

➡ Lung cancer and mesothelioma

Tobacco Smoke

• From combustion of tobacco products in:

➡ Cigarettes

➡ Cigars

➡ Pipes

• Similar smoke from other combustible products

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Partial List of Tobacco Smoke Constituents

Carbon monoxide

Nitrogen oxides

Hydrogen Cyanide

Acrolein

Acetaldehyde

Formaldehyde

Hydrazine

Vinyl Chloride

Nicotine, Tar

Urethane

2-nitropropane

Quionoline

Nitrosamines

Nickel carbonyl

Benzo(a)pyrene

5-methylchrysene

210Polonium

Cadmium

Sidestream Smoke(Environmental Tobacco Smoke)

Same as Mainstream smoke gases

+ Smoldering cigs

Cooler

Less efficient

burn

Higher CO content

Sidestream Smoking

• Dosage—Depends on number of smokers, room volume, ventilation, distance from cigarette(s)

• One pack of cigarettes = 20 µg/m3 of particulates per day

• Near smoker, 500–1000 µg/m3

• Health effects: eye irritation, aggravation of asthma, increased respiratory tract illness, cardiovascular and heart disease, lung cancer

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Regulation

• No NAAQS for indoors

• Occupational Safety and Health Administration (OSHA) has workplace standards

➡ These standards are less stringent than outdoors

• Workers are a healthier subset of general population

• Photochemical smog is not an indoor problem

Indoor Air Pollution Remediation

• Reduce polluting activity

➡ Decreases the source rate

• Enhance ventilation

➡ Decreases residence time or increases mixing volume

• Live plants (?)

• Filtration (air cleaners)

➡ Anthropogenically enhanced deposition

Filtration

• Mechanical: fiber-based filtration medium traps aerosol particles

➡ Fibers: paper, cotton/cloth, fiberglass

• Sorbents: materials that capture gas molecules out of the air

➡ Granulated Activated Charcoal (GAC)

➡ Zeolite

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