Different Aspects of Indoor Air Pollution

INDOOR AIR POLLUTANTS AND ITS SOURCES

Combustion Products

• Carbon monoxide (CO)
• Nitrogen dioxide (NO2)
• Sulfur dioxide (SO2)
• Nitrogenized compounds (NOx)
• Particulate matter (PM)

Objects such as wood stoves, space heaters, and fire places all put out the carbon monoxide as well as nitrogen dioxide. Incomplete oxidation during combustion in gas ranges and unvented gas also kerosene heaters may cause the high concentrations of CO in indoor air.Other sources are

• Gas stoves and appliances
• Wood, fire bricks and coal stoves
• Gas and propane engines
• Fireplaces
• Tobacco smoke
• Candles and incense
• Mosquito coils etc.

Volatile Organic Compounds (VOCs)

• Alkanes
• Aromatic Hydrocarbons
• Alcohols
• Aldehydes
• Ketones, etc.

List of these possible sources are:

• Solvents, fabric softeners, deodorizers and cleaning materials
• Paints, waxes, resins, glues and polishing materials
• Spray propellants, dry cleaning fluids
• Pens and markers
• Cosmetics: hair sprays and perfumes etc.

Example:

Pollutant: Formaldehyde

Sources:

Developing countries

• Use of solid fuels in indoors
• Mosquito coils in houses
• Furniture

Industrialized countries

• Household cleaners
• Glues resins
• Smoke of Tobacco
• Carpeting
• Furniture and dyed materials
• Pressed wood products
• Urea formaldehyde insulating foam (UFFI)

Asbestos

Possible sources are:

• Asbestos can be found in different materials used in commonly in the automotive industry as well as home construction.
• Demolition of constructions containing asbestos in products as coatings, paints, building materials, and ceiling and floor tiles

Biological Pollutants

• Molds
• Bacteria
• Dust Mites
• Animal allergens

List of major sources are;

• Water-damaged surfaces and materials
• Humidifiers and stagnant water
• Water vapor from cooking and showering
• Air conditioning systems
• Mattresses upholstered furniture and carpets
• Dirt
• Cat dander (most allergenic)
• Dog dander
• Birds
• Cockroach parts and feces

Radon

Radon is a radioactive gas that comes from the soil. Radon is produced from the natural break down of thorium and uranium found in most of rock and soils. As breaks down radon emits atomic particles. These particles are in the air which we breathe can be deposited in the lungs. Energy associated with these particles can alter DNA leading to an increased risk of lung cancer.

Ozone

Ozone is a molecule composed of three atoms of oxygen. The third oxygen atom can dissociated from the ozone molecule and reattach to molecules of other substances and thereby alter their chemical composition. Scientific evidence shows that at the concentration that does not exceed public health standards. Ozone has little potential to take out indoor air contaminants there is no approval for its use in occupied spaces.

Outdoor Air Pollutants

In some cases outdoor pollution or pollutants also can be the cause of indoor air pollution. Factories, vehicles and other sources emitting pollutants can enter the home and in absence of proper ventilation can cause the health effects to the habitants. This is particularly seen in the unplanned urban areas

Strategies to Control Indoor Air Pollution

• Source Control
• Ventilation
• Air Handler
• Air Filtration

Types of air cleaners i.e. air filtration include

• ¾ Mechanical filters which include the typical furnace or AC filter.
• ¾ Electronic air cleaners for (example, electrostatic precipitators) which trap charged particles using an electrical field.
• ¾ Ion generators which act by charging the particles in a room. The charged particles are then attracted to walls, floors, and draperies etc. or in a charged collector.
• ¾ Hybrid devices, which contain two or more of the particle removal devices discussed above.

• Mechanical Filtration
• Electronic Air Cleaners
• Self-Cleaning Electronic Air Filters
• Houseplants

References:
1. Mackenzie L. Davis & David A. Cornwell, “Introduction to Environmental Engineering”, McGraw-Hill.
2. Gilbert M. Masters, Standford University, “Introduction to Environmental Engineering and Science”, Prentice Hall.
3. Stephan Konz, Kansas State University, “Work design”, Grid Publishing Inc., Colombus, Ohio
3. C. S. Rao, “Environmental Pollution Control Engineering”, New age International (P) Limited, Publishers, India.