Indoor Environmental Quality Basics
You have probably lived through at least one scenario where you ask yourself, “Is this building making me sick?” Maybe upon investigation you found something that was obviously amiss and easily corrected. But a number of things likely went wrong, and the complaints were validated. In this month’s column, we intend to help you avoid some common indoor air quality issues and proactively defuse the most common building-related illnesses and complaints.
We strive to maintain employee and occupant health; comfort and productivity are also essential in managing indoor environmental quality effectively. This month the Safety Guys provide a few guidelines for avoiding and minimizing negative impacts of poor indoor air quality, building renovation projects, or adjacent new construction.
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We advise you to involve your environmental health and safety (EH&S) office at the outset. Today, most EH&S programs will have an indoor environmental quality (IEQ) policy and personnel familiar with solving IEQ problems. If given the opportunity, make sure to review renovation and construction projects in advance with all occupants of the impacted areas. If any of our recommendations given here vary from traditional or consensus guidelines or local codes, try to apply the more stringent of the two.
The most common indoor environmental quality concerns stem from construction and renovation projects and include transient smells, nuisance odors, noise, and dust. Building occupants can experience mucous membrane irritation and headaches as well as aggravated allergies or asthma-like symptoms from these contaminants, even at very low concentrations. In addition, excessive noise can have a definite effect on focus, concentration, and productivity. If contaminants are repeatedly introduced into the occupied areas, workers are going to let you know about it, and rightfully so. However, most of these conditions affecting indoor environmental quality and employee comfort, productivity, and health are preventable and reversible. Based on our many years of experience dealing with IEQ complaints in occupied spaces, the following tips can keep your employees happy, healthy, and productive.
First, ensure the ventilation systems supporting the occupied complaint areas are consistent with all appropriate recommendations of the latest version of the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 62, Ventilation for Acceptable Indoor Air Quality.1 In other words, make sure enough fresh air is being brought in, supply volumes meet design, and filtering is adequate.
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If the complaints are about musty odors or mold, look for obvious visible mold growth or excess moisture. Find out whether there has been a recent or prolonged water intrusion event. Fix the moisture issue, and clean off any visible mold with a soap-and-water solution.
Make sure any construction/renovation project areas are separated from adjacent occupied areas with full-height, hard wall barriers. This type of barrier will effectively block any transmission of dust, odors, or other contaminants. In addition, isolate any construction zones from the adjoining work areas to attenuate noise as much as possible.
Maintain any construction/renovation areas at a slight negative air pressure relative to the adjacent occupied spaces. If these work areas go to positive pressure, then contaminants, dust, and odors might find their way into nearby offices and labs. Set up and maintain negative pressure by adjusting the HVAC system, or install additional exhaust ventilation to support the construction/renovation work. If local exhaust ventilation (LEV) is used, it should follow the recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines in Industrial Ventilation, a Manual of Recommended Practice.2
For any construction/renovation work, try to segregate all areas utilized for containment. Locate any odor- or contaminant-generating activities away from outside air intake systems, and ensure adequate exhaust air is provided. Alternatively, the return air vent in the construction/ renovation area could be blocked off temporarily.
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Make sure regular, daily housekeeping is performed to prevent construction workers from tracking dust and debris outside the work area and into occupied spaces. If possible, set up decontamination zones or antechambers so workers can wipe down and clean off before leaving the construction area. Use of sticky mats greatly reduces dust and debris being carried by worker footwear. Your facility housekeeping staff will also appreciate their use.
Request that facility maintenance personnel perform routine checking and replacing of HVAC system air filters. Use more efficient filters if dust loading in adjacent occupied areas becomes excessive. We recommend pleated, extended surface area filters with a minimum dust spot efficiency of 60 percent (MERV 11).
Many construction and renovation projects use equipment that produces odors or contaminants, and often these are set up outside. Examples include roofing tar pots, spray equipment, pressure washers, portable gas- or diesel-powered engines or generators, and portable showers/ lavatories. Any such equipment set up outside must be carefully located well away from any ventilation system air intakes and building entrances to prevent re-entrainment of contaminants.
Make sure that material safety data sheets (MSDS) are maintained on-site for all chemical products used during any construction or renovation process. When the inevitable calls start coming in, you will need to know what the contaminants are so appropriate actions can be initiated.
Even if you are extremely meticulous, chances are that something will upset the delicate indoor air quality balance at some point. There may be times when good IEQ just is not possible. When these cases arise, your only alternative may be to have a professional investigate. It is not often you run into these situations, but sometimes the issue is not obvious or easily found. Good luck with your next IEQ complaint, and remember—safety first!
1. Ventilation for Acceptable Indoor Air Quality. American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 62-2009. Atlanta, Georgia.
2. Industrial Ventilation, a Manual of Recommended Practice. American Conference of Governmental Industrial Hygienists (ACGIH). 27th Edition, 2010. Cincinnati, Ohio.