How Air Quality Affects Our Health

A study conducted by the U.S. Environmental Protection Agency (EPA) found that indoor exposure to harmful air pollutants could be up to 100 times greater than outdoors. The EPA now classifies indoor air quality as one of our most important environmental concerns.

According to the National Institute of Allergy and Infectious Diseases (part of the National Institute of Health), indoor airborne allergens and pollutants can trigger a wide range of symptoms including:

  • Allergic rhinitis

  • Sinusitis

  • Headaches

  • Fatigue

  • Nausea

  • Depression

  • Dermatitis

  • Rash

  • Sore throat

  • Nasal congestion

  • Itchy or watery eyes

People with weakened immune systems can be especially susceptible to more severe complications, such as bronchial infections or pneumonia. While medical science has made great strides in developing medications to treat allergic reactions, health professionals generally recommend reducing or eliminating exposure over merely treating symptoms.

Types Of Indoor Air Pollutants

The Centers for Disease Control and Prevention (CDC) places air pollutants into three general categories:

1. Particulates
2. Bioaerosols
3. Volatile Organic Compounds


Particulates

Particle size rangeCommon indoor air particulates include dirt, dust, fibers, tobacco smoke particles and fireplace or wood stove soot. Airborne particles can range from 0.1 microns in size to 100 microns in size; however, studies have shown that more than 99% of the particles suspended in air are ultra-fine, one micron (1/1,000,000 of a meter) or smaller. To put this size in perspective, the width of a human hair is about 50 to 200 microns. Most of us can’t see particles smaller than 10 microns. These particles can remain airborne for very long periods of time, unlike larger particles that tend to settle on surfaces.



Ultra-fine particles are called “respirable” particles because they are inhaled in the lungs and are small enough to bypass the human body’s defense mechanisms. According to the American Lung Association, "While larger particles (greater than 10 microns in diameter) get caught in the nose and throat, and are cleared naturally by coughing or swallowing, particles smaller than 10 microns in diameter are easily inhaled into the lungs. Of these, the smallest particles are most likely to reach the alveoli, where they can remain embedded for years, or in the case of soluble particles, be absorbed into the bloodstream.”

Bioaerosols

Bioaerosols are particulates from human matter. Examples include microbial pollutants such as bacteria, molds and fungi, dust mite and insect remains, pet dander and pollens. Fungus-related infections are now thought to be the leading cause of asthma attacks and allergic respiratory reactions in humans. In a 1999 study, researchers from the renowned Mayo Clinic in Rochester, Minnesota found that 96 percent of the cases of chronic sinusitis were related to fungal and mold infections.

Bioaerosols typically range in size from 0.1 to 10 microns, with most particles smaller than one micron. Bioaerosols such as molds (Aspergillus) or dust mites are often present in dust or dirt particles, which they feed on, and can be inhaled along with these particles. The potential harmful health affects of molds such as Aspergillus and Stachybotris have been well publicized over the past few years. Thousands of mold species have been identified, and scientists suspect that many more have not.

Some molds can also produce compounds known as mycotoxins to defend their “territory” against bacteria and other molds. Some scientists and health professionals believe that mycotoxins may be the cause of lung ailments, hemorrhage, coughing, memory loss, chronic fatigue and other symptoms attributable to indoor air quality problems.

Molds feed on materials such as cellulose that are commonly used in the construction of our homes, making our homes almost a perfect habitat for many species. They produce tiny spores that float easily through the air. When these spores land on damp surfaces they can begin to grow and proliferate.

Volatile Organic Compounds (VOC)

Volatile organic compounds include potentially harmful or irritating derivatives of alcohols, ketones, hydrocarbons and aromatics, such as formaldehyde or benzene. VOC are often created from “off-gassing” of man-made materials such as carpeting, composite wood products or household chemicals. They can also be caused by secondhand tobacco smoke, which is known to include more than 200 different VOC.

Some molds and other fungi can produce microbial VOC (MVOC) that can be toxic to humans. MVOC can especially affect people with allergies, asthma or other sensitivities, or suppressed immune systems. MVOC emissions may also include unpleasant odors, such as the characteristic musty smell often associated with molds. MVOC can also cause more serious indoor air odor problems, such as “dirty socks syndrome.”

Home IAQ Check List

If you can answer yes to two or more of the following questions, you may want to take steps to improve the IAQ of your home:

  • Does anyone in your family suffer from allergies, asthma or other respiratory problems?

  • Do they notice that their symptoms (headaches, fatigue, nasal congestion, sore throat, etc.) are worse at night or in the morning?

  • Does any family member have immune system problems or illness?

  • Do you have an infant child or elderly family member?

  • Is there a smoker in the house?

  • Are there any pets?

  • Do you notice a stale or musty odor when the furnace or air conditioner runs?

  • Do you notice dust on furniture shortly after cleaning?

  • Is your home new?

  • Is your home more than 10 years old?

  • Does dirt or dust accumulate on your supply or return air grills?

A Healthy HVAC System Means Cleaner Indoor Air

IAQ experts now estimate that more than 70% of all indoor air quality problems involve the operation and/or maintenance of HVAC systems. Like any other part of a home or building, dirt, dust and other particulates can accumulate on system components and in ductwork. Studies have shown that even a thin coating of dirt and dust on critical HVAC components can significantly reduce energy efficiency.

Some duct systems are insulated with fiberglass or fiberboard on the inside surfaces for sound insulation. These materials can trap dirt, particulates and bioaerosols. They can also absorb moisture from the air stream, making these surfaces a perfect breeding ground for additional microbial growth.

HVAC systems are most susceptible to moisture-related microbial problems during the warmer months, especially when air conditioning is used. In the cooling cycle, cooling coils reduce the temperature of the warm air. Much of the excess moisture is condensed into water and collected in a drain pan. However, the relative humidity of the air coming out of the coils is often elevated as well, making these and any downstream HVAC components vulnerable to mold, fungi and bacteria proliferation. Cold-water humidifiers can also increase mold growth by increasing the moisture in the air.

Homes in hot, humid climates or homes that have experienced moisture, water or sewage leakage problems are at even greater risk of microbial contamination.

Standard throwaway furnace filters and even many “upgraded” filters provide very little protection against microbial contaminants or ultra-fine particles. Each time the HVAC fan cycles air into the home, armies of potentially harmful spores, along with other allergens and pollutants, can be propelled through the supply ducts and spewed throughout your home into the air your family breathes.