Editor's Note: Part 1 of this series was published on June 17,2008. In case you missed it, read it here.

In Part 1 of this series, we looked at how key pollutants may be affecting the quality of air in your workplace and how poor indoor air quality (IAQ) affects the health of your employees. This week, let's take a look at one of the most important systems available to you to manage IAQ: the heating, ventilation and air conditioning (HVAC) system.

Design, Maintenance & Operation of Ventilation Systems

HVAC systems include all of the equipment used to ventilate, heat and cool the building, to move the air around the building (ductwork), and to filter and clean the air. These systems can have a significant impact on how pollutants are distributed and removed. Maintaining good indoor air quality requires attention to the building's HVAC system.

The system's ability to perform properly can be affected by increased numbers of occupants and additional or relocated heat sources (such as computers or other equipment). In some cases, HVAC systems can even act as sources of pollutants, such as when ventilation air filters become contaminated with dirt and/or moisture and when microbial growth results from stagnant water in drip pans or from uncontrolled moisture inside of air ducts.

Because of the HVAC system's importance, good IAQ management includes paying attention to these seven features:

1. Ventilation System Design

The air delivery capacity of an HVAC system is based in part on the projected number of people and amount of equipment in a building. When areas in a building are used differently from their original purpose, the HVAC system may require modification to accommodate these changes. For example, if a storage area is converted into space occupied by people, the HVAC system may require alteration to deliver enough conditioned air to the space.

2. Outside Air Supply

Adequate supply of outside air, typically delivered through the HVAC system, is necessary in any office environment to dilute pollutants that are released by equipment, building materials, furnishings, products and people. Effective distribution of ventilation air to occupied spaces is also essential for comfort.

3. Outdoor Air Quality

When present, outdoor air pollutants, such as carbon monoxide, pollen and dust may affect indoor conditions when outside air is taken into a building's ventilation system. Properly installed and maintained filters can trap many of the particles in this outdoor supply air. Controlling gaseous or chemical pollutants may require more specialized filtration equipment.

4. Space Planning

The use and placement of furniture and equipment may affect the delivery of air to an occupied space. For instance, the placement of heat generating equipment, like a computer, directly under an HVAC control device, such as a thermostat, may cause the HVAC system to deliver too much cool air, because the thermostat senses that the area is too warm. Furniture or partitions that block supply or return air registers can affect IAQ as well, and need to be positioned with attention to air flow.

5. Equipment Maintenance

Diligent maintenance of HVAC equipment is essential for the adequate delivery and quality of building air. All well-run buildings have preventive maintenance programs that help ensure the proper functioning of HVAC systems.

6. Controlling Other Pollutant Pathways

Pollutants can spread throughout a building by moving through stairwells, elevator shafts, wall spaces and utility chases. Special ventilation or other control measures may be needed for some sources.

7. Moisture & Humidity

It is important to control moisture and relative humidity in occupied spaces. The presence of moisture and dirt can cause molds and other biological contaminants to thrive. Relative humidity levels that are too high can contribute to the growth and spread of unhealthy biological pollutants, as can failure to dry water-damaged materials promptly (usually within 24 hours) or to properly maintain equipment with water reservoirs or drain pans (e.g., humidifiers, refrigerators and ventilation equipment). Humidity levels that are too low, however, may contribute to irritated mucous membranes, dry eyes and sinus discomfort.

Conclusion

Maintaining a good HVAC system is just a start. There are a few other ways that you and your employees can improve the indoor air quality in your workplace. We'll discuss these in the conclusion of our series next week.

WILDIFIRES AND AIR QUALITY

13 Recommendations from the American Lung Association

By Catherine Jones

Wildfires are threatening many communities across Canada and the United States this week, spreading with them dangerous air pollution. In addition to the threats posed by the fires themselves, this air pollution poses potentially lethal health hazards to anyone working and living in the surrounding areas, endangering especially those with respiratory problems such as asthma, emphysema and bronchitis, as well as chronic heart disease.

"People with respiratory problems and chronic heart disease are at greatest risk during this time," says Norman Edelman, MD, Chief Medical Officer of the American Lung Association. "Due to the extremely high levels of pollutants, many people may be experiencing increased symptoms and should contact their doctor promptly, especially those using oxygen. People using oxygen are strongly cautioned to not adjust their levels of intake without consulting their doctor first."

But according to Edelman, even if you don't have a respiratory or heart problem, you should still take precautions. "Even those without lung diseases are at risk during this time. With the rising air pollution levels we are seeing in the affected areas, there is increased risk of coughing and wheezing, asthma attacks, as well as heart attacks and strokes, especially for older adults and outdoor workers. Take special care to protect children. They are more susceptible to smoke, because their respiratory systems are still developing."

Here are 13 recommendations from the American Lung Association for those living and working in the surrounding areas of wildfires:

More information on how to protect yourself during wildfires is available at the American Lung Association website.

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