Q: Why is indoor air quality (IAQ) important?

A: One in five Canadians suffers from some type of lung disease (asthma, emphysema, lung cancer) and many more Canadians are affected by allergies. The air we breathe is a factor in all these conditions; therefore, it is vital that we implement the necessary steps to ensure the highest level of indoor air quality.

Canadians spend an average of 90% of their time inside, and our homes and offices contain many substances that may be hazardous to our health. A major cause of poor indoor air quality is lack of fresh air - that is, not enough exchange of air between the outside and inside.

Indoor air pollutants range from minor irritants such as dust and animal dander, to major irritants such as mold and chemical vapors that may be emitted from building materials and furnishings.

Q: What are some factors that contribute to indoor air quality (IAQ)?

A: While most buildings don't have severe IAQ problems, even well run buildings can sometimes experience episodes of poor IAQ.

But what exactly is indoor air quality? It's not a simple, easily defined problem like a wobbly desk or a leaky faucet. IAQ is a constantly changing interaction of complex factors that affect the types, levels and importance of pollutants in indoor environments. These factors include:

  • Sources of pollutants or odors
  • Design, maintenance and operation of building ventilation systems
  • Moisture and humidity
  • Occupant perceptions
  • Susceptibilities, etc.

Q: What is Indoor Air Quality Testing?

A: In reality, there is no one "indoor air quality test." Testing the indoor environment can refer to a wide range of tests, different testing methods (air, bulk & surface samples,) and myriad contaminants or surrogates (indicators of contaminants) to test for. There is no one test that can be used to determine the safety or healthfulness of an indoor environment.

Two of the primary factors that are required for a suitable indoor environment are temperature and relative humidity. Temperature control is always a considered parameter when designing a workspace. However, proper control of relative humidity and its relationship to Indoor Air Quality (IAQ) are overlooked many times.

IAQ test equipment usually monitors moisture and temperature along with other parameters such as nitrogen dioxide (diesel fumes), carbon monoxide, carbon dioxide, and other gases.

Airborne mold can be detected as well.

Q: What is Relative Humidity?

A: Defined as the amount of moisture in the air, humidity measurement and control is required in many industries such a heating and air conditioning, food processing and transportation, agriculture and industrial processes. Our thermo-hygrometers measure both relative humidity and ambient temperature, some also measure dew point.

Relative humidity (RH) is the ratio of the quantity of water vapor in the air to the quantity of water vapor required for saturation at the same temperature.

Another common indication of humidity is dew point. Dew point is the temperature which water vapor begins to form condensation. Dew point can be derived from relative humidity and ambient temperature.

Heat stress is the effect on the body's ability to cool itself when facing high temperature and humidity. Often this occurs when working in hot environments and is especially hazardous during the summer months. Common effects of heat illness include: heat cramps, heat exhaustion and heat stroke, with heat stroke being a life-threatening condition.

There are four environmental conditions that may affect heat stress in an individual: ambient temperature, humidity, radiant heat (ie. oven, furnace) and air velocity.

Important to the level of stress the individual faces are personal characteristics such as age, weight, fitness, medical conditions, acclimatization to the heat and even the clothing or safety equipment worn by the individual. An inspection of the workplace can help determine in advance if heat is likely to be a hazard. Once the problem has been found, more often than not, it is a simple procedure to correct. Common place solutions include installing reflective barriers for heat sources, increasing the exhaust of hot air, increasing ventilation or reducing physical demands of work task through mechanical assistance (hoists, lift-tables ...)

In a 1985 study by Dr. Elia Sterling, Criteria for Human Exposure to Humidity in Occupied Buildings, he reviewed the psychological effects that indoor rh levels had on people and concluded that the optimum range should be within the 40% - 60% range. Dr. Sterling's study details the effects that both high and low relative humidity levels have on people in the workplace. At the midrange, many of the bacteria, viruses, etc. lose their viability, and many cases studies indicate the organisms died and have little affect on the occupants.

As relative humidity rises, bacteria, viruses, etc. have an increasingly greater detrimental affect on the occupants. In the modern office environment, high rh levels are usually reduced to the 50% or 60% level by a properly designed hvac system.

However, humidity can drop to the subdesert conditions as low as 3% rh. This will have a dramatic and detrimental affect on the occupants. Dry skin problems, flu, colds, pneumonia, and other respiratory ailments are usually associated with wintertime conditions when the indoor rh levels are at their lowest levels. These lead to greatly increased absenteeism levels and lost productivity, costing billions of dollars to employers each year. Significant increases in the cost of health care benefits can be attributed to wintertime ailments.

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