Chapter 25: Indoor Air Pollution

Sources of Indoor Air Pollution

• Secondhand smoke – Most hazardous common indoor air pollutant •

Legionella pneumophila

– Bacterium that causes a type of pneumonia called Legionnaires’ disease when inhaled.

• Some molds (fungal growths) in buildings release toxic spores.

– Cause chronic inflammation and scarring of lungs

Sources of Indoor Air Pollution

• Radon gas – seeps up naturally from soils and rocks below buildings – Thought to be the second most common cause of lung cancer.

• Pesticides – Deliberately or inadvertently applied in buildings to control pest – Are toxic to people as well

Sources of Indoor Air Pollution

• Some varieties of asbestos – Known to cause a particular type of lung cancer • Formaldehyde – A VOC, used in many materials found in homes and offices. – Emit formaldehyde as a gas into buildings. • Dust mites and pollen – irritate the respiratory system, nose, eyes, and skin of people who are sensitive to them.

Dust mite

Pollen grains

Sources of Indoor Air Pollution

• Common indoor air pollutants are often highly concentrated compared with outdoor levels. • Why?

– There are so many potential indoor sources of pollutants. (Furniture, beds, carpet, plastics) – The effectiveness of the steps we have taken to conserve energy in buildings (ie, weather stripping) has led to the trapping of pollutants inside.

Heating, Ventilation, and Air Conditioning Systems

• Systems are designed to provide a comfortable indoor environment for people. • Design depends on a number of variables – Including the activity of people in the building, air temperature and humidity, and air quality. • Done correctly it will – Provide thermal comfort for people inhabiting the building. – Provide the necessary ventilation (utilizing outdoor air) – Remove common air pollutants via exhaust fans and filters

Pathways, Processes, and Driving Forces

• Many air pollutants originate within buildings and may be concentrated there because of lack of proper ventilation.

• Other air pollutants may enter by infiltration, – Through cracks and other openings in the foundations and walls (Radon, VOC’s) – Or by way of ventilation systems. (proximity to roads)

Pathways, Processes, and Driving Forces

• A chimney effect (or stack effect) – Occurs when there is a temperature differential between the indoor and outdoor environments.

– Warmer air rises in the building to the upper levels, it is replaced in the lower portion of the building by outdoor air.

– Secondhand smoke, may also be drawn into a building by the chimney effect.

Building Occupants

• People living or working in particular indoor environments react to pollutants in different ways: – Some groups of people are particularly susceptible to indoor air pollution problems.

– The symptoms reported by people in a particular environment vary.

– In some cases, the symptoms reported result from factors other than air pollution.

Particularly Susceptible People

• A person’s susceptibility to a particular air pollutant also depends on genetic factors, lifestyle, and age.

– Sometimes a matter of concentration rather than susceptibility.

– Older people and children are generally more sensitive.

– People suffering from chronic lung or respiratory diseases are more susceptible.

– Individuals who have suppressed immune systems.

– Some people, when exposed to chemicals, develop multiple chemical sensitivity (MCS).

Symptoms of Indoor Air Pollution

• A great variety of symptoms can result from exposure to indoor air pollutants. – Nosebleeds, chronic sinus infections, headaches, and irritation of the skin or eyes, nose, and throat. – More serious problems include loss of balance and memory, chronic fatigue, difficulty in speaking, and allergic reactions, including asthma. – Other pollutants cause dizziness or nausea. – Radon, asbestos, and chemicals such as benzene, may have long-term chronic health effects (cancer).

Sick Buildings

• There are two types of sick buildings: – Buildings w/ identifiable problems • Occurrences of toxic molds or bacteria known to cause disease. • Diseases are known as building-related illnesses (BRI).

– Buildings w/ sick building syndrome (SBS) • Symptoms people report cannot be traced to any one known cause.

Sick Buildings

• When the cause is not detected. A number of things may be happening: – The complaints result from the combined effects of a number of contaminants present in the building.

– Environmental stress from another source is responsible.

– Employment-related stress may be leading to the symptoms reported.

– Pollutants or toxins may be present but not identified.

Environmental Tobacco Smoke

• Environmental tobacco smoke (ETS) – Secondhand smoke – Comes from two sources: • smoke exhaled by smokers • smoke emitted from burning tobacco in cigarettes, cigars, or pipes. – People who are exposed to ETS are referred to as passive smokers.

Environmental Tobacco Smoke

• It is hazardous for the following reasons: – Tobacco smoke contains several thousand chemicals, many of which are irritants. – Studies of nonsmoking workers exposed to ETS found that they have reduced airway functions, suffer more illnesses, and lose more work time than those not exposed to ETS.

– In the US, about 3,000 deaths from lung cancer and 40,000 deaths from heart disease a year are thought to be associated with ETS.

Radon Gas

• Radon is a naturally occurring radioactive gas that is colorless, odorless, and tasteless. – Radioactive decay chain from radiogenic uranium to stable lead – Radon-222 has a half-life of 3.8 days, is the product of radioactive decay of radium-226. – Radon decays with emission of an alpha particle to polonium-218, which has a half-life of ~ 3 minutes

Geology and Radon Gas

• The concentration of radon gas that reaches the surface of the Earth and thus can enter our dwellings is – Related to the concentration of radon in the rocks (generally granitic rock) and soil. – Some regions in the United States contain bedrock with an above-average natural concentration of uranium.

How Does Radon Gas Enter Building?

• Radon gas enters homes and other buildings in three main ways: – 1. It migrates up from soil and rock into basements and lower floors.

– 2. Dissolved in groundwater, it is pumped into wells and then into homes.

– 3. Radon-contaminated materials, such as building blocks that are used in construction.

Radon Resistant Techniques for Homes and Other Building

• Protection is straightforward and relatively inexpensive.

• Techniques are variable depending on the type of foundation a particular home has, – The basic strategy is to prevent radon from entering – And to safely ensure that radon is removed from the home site.

• A. Gas Permeable Layer: – Allow the soil gas to move freely underneath the house.

• B. Plastic Sheeting: – Help prevent the soil gas from entering the home. • C. Sealing and Caulking: – Openings in the concrete foundation floor are sealed to reduce soil gas entry into the home.

• D. Vent Pipe: – A PVC pipe runs from the gas-permeable layer through the house to the roof to safely vent radon above the house.

• E. Junction Box: – An electrical junction box is installed if an electric venting fan is needed.

Indoor Air Pollution and Green Buildings

• Building green.

– The processes involves using building designs that result in less pollution and better use of resources.

– Providing for a good indoor environmental quality is a significant part.

• Designing, constructing, and maintaining buildings that minimize indoor air pollutants.

• Ensuring that fresh air is supplied and circulated, and managing moisture content to remove the threat of moisture-related problems such as mold.

Control of Indoor Air Pollution

• There are strong financial incentives to provide workers w/ a clean air environment.

• A good starting point would be passing environmental legislation requiring minimum indoor air quality standards. – Including increases in the inflow of fresh air through ventilation. This concept is at odds with the principles of Energy Efficiency….

Control of Indoor Air Pollution

• One of the principal means for controlling quality is by dilution – Fresh outdoor air mixed via a ventilating air conditioning system and windows that can be opened. • Various types of air-cleaning systems reduce potential pollutants – Such as particles, vapors, and gases. – Can be installed as part of the heating, ventilation, and AC system or as stand-alone appliances.

Control of Indoor Air Pollution

• Education also plays an important role – May involve deciding not to install unvented or poorly vented appliances.

– Educated people are more aware of their legal rights with respect to product liability and safety. – Education provides people with the information necessary to make decisions concerning exposure and strategies to avoid potentially hazardous conditions in the home and workplace.