Fundamentals of Indoor Air Quality

Refrigeration Service Engineers Society 1666 Rand Road Des Plaines, Illinois 60016 FUNDAMENTALS OF INDOOR AIR QUALITY Frank Prah, CMS INTRODUCTION Indoor air quality in earlier times HVAC technicians are not medical doctors or indus- Anthropologists and forensic scientists know that trial hygienists. However, it is estimated that over primitive humans who lived in caves often suffered 80% of IAQ-related problems could be remedied by from poor IAQ. Smoke inhalation, dampness, and improving the design or maintenance program of generally unsanitary conditions, combined with a HVAC systems. The conclusion is obvious—in many poor diet, led to respiratory problems and arthritis. cases, a trained HVAC technician can improve the Smoke was also a problem in the Native American IAQ of a building or facility. tepee. The tepee actually had a ventilation system that worked reasonably well. However, the Indians An HVAC system serves as a distribution network for who lived in tepees had the same problem that we properly conditioned and filtered air in a building. The have today, especially during the winter. When we same system can serve as a path—and sometimes a increase ventilation, we pay an energy price. They source—for airborne pollutants. The contaminants also had to put up with cold drafts. Interestingly, some can and do affect the health and productivity of the winter camping sites were recently studied and com- building’s occupants. bustion air tunnels were found that led from outside the tepee to its center, where the fire was located. In the past, most of the instruction that a HVAC tech- Today, of course, heat wheels or heat tubes serve as nician received revolved around the mechanical, pip- heat exchangers and help reduce the energy penal- ing, and electrical aspects of installing and servicing ties associated with using outside air. Some claim equipment. Environmental concerns were rarely dis- 80% efficiency rates. cussed. Today the environmental aspects of HVAC systems are becoming much more important, and Indoor air quality in recent times cannot be ignored. Before the energy crunch in the early 1970s, indoor Outbreaks of Legionnaire’s disease have been air quality wasn’t as much of a problem as it is now. traced to air conditioning systems. There are news At that time, buildings were not as “tight” as they are reports about buildings that make their tenants sick. today, and the cost of bringing in outside air was not Individual homes are linked to increases in allergies a significant factor. In many cases, the quality of the and asthma. Can this happen to your home, or to the outside air was also better. In the mid-1970s, how- building that you service? What can you do to prevent ever, operating and maintenance costs for commer- it or correct it? cial buildings escalated rapidly, largely because of rising fuel prices and higher utility rates. Contractors Growing concerns about indoor air quality present began to construct “tighter” buildings and added HVAC technicians and contractors with increased more insulation. A house built prior to the 1970s may opportunities. Knowledgeable HVAC professionals have had one or two “natural” air changes per hour. A can assist building owners and managers in solving new house today may have one-tenth of an air problems and avoiding the expensive repairs and change per hour. high legal costs associated with poor indoor air quality. (Indoor air quality, or IAQ, is also referred to as Most people are aware that outdoor air pollution can indoor environmental quality, or IEQ.) damage their health, but may not know that indoor air © 2002 by the Refrigeration Service Engineers Society, Des Plaines, IL 630-135 Supplement to the Refrigeration Service Engineers Society. 1 Section 17A pollution can also have significant effects. EPA stud- IAQ problems may stem from the fact that school ies of human exposure to air pollutants indicate that administration and maintenance personnel do not indoor air levels of many pollutants may be 2 to 5 understand how to operate ventilation systems, and times—and in some cases more than 100 times— from the introduction of contaminants, such as plug- higher than outdoor levels. High levels of indoor air in chemical deodorizers and art supplies, into class- pollutants are of particular concern in our society rooms. today because most people spend more time inside than outside. In fact, it is estimated that many of us SICK BUILDING SYNDROME2 spend more than 90% of our time indoors (including time spent at home, at work, in the car, shopping, The term “sick building syndrome” surfaced in the etc.). Despite the fact that most people spend more 1970s when, to conserve energy, many naturally ven- time in their homes than at work, the majority of IAQ tilated homes, schools, and offices were replaced complaints originate in the workplace. with tightly sealed, air conditioned buildings. Insula- tion, treated wood, volatile adhesives, and synthetic Over the past several decades, our exposure to fabrics, furnishings, and carpets were often incorpo- indoor air pollutants is believed to have increased rated into these buildings. Especially when new, due to a variety of factors, among them the construc- many of these products release low levels of poten- tion of more tightly sealed buildings, reduced ventila- tially harmful chemicals, such as formaldehyde, into tion rates (widely practiced as a means of saving the recycled air. Carpets can add to the problem by energy), the use of synthetic building materials and absorbing various cleaners and solvents and then furnishings, and the prevalence of chemically formu- releasing them over a long period of time. lated personal care products, pesticides, and house- hold cleaners. In recent years, comparative risk A book entitled Chemical Exposures: Low Levels studies performed by the EPA and its Science Advi- and High Stakes states that “vapors from various sol- sory Board (SAB) have consistently ranked indoor air vents are the most prevalent of indoor air contami- pollution among the top five environmental risks to nants,” and goes on to point out that “solvents are public health. among the chemicals most frequently implicated by chemically sensitive patients.” Many people like the IAQ problems in schools1 smell known as “new car smell,” produced by the volatile organic compounds (VOCs) found in new U.S. government studies have shown that one in five cars. But many of the same materials—upholstery, schools has IAQ problems, but they are problems adhesives, carpeting, and other such outgassing that can be improved through the use of active components—are found in so-called “sick” buildings. humidity control and continuous ventilation. More than 8 million students are affected by IAQ problems, While most people seem to be able to cope with the according to government research outlined in an arti- environment inside such buildings, some develop cle in IAQ Applications , published by ASHRAE symptoms ranging from headaches and lethargy to (American Society of Heating, Refrigeration and Air- asthma and other respiratory tract problems. These Conditioning Engineers). Problems can include symptoms generally disappear when the affected drowsiness, lack of concentration, and headaches, people leave the environment. But the British medical all of which affect the student’s comprehension and journal The Lancet notes that in some cases, motivation. “patients may develop multiple chemical sensitivi- ties.” Why do some individuals get sick from chemi- Dr. Charlene Bayer, of Georgia Tech Research Insti- cals while others do not? This is an important tute, says that IAQ should be a top priority because question, not least because those who seem to be children, who are still developing physically, are more unaffected may find it difficult to be understanding of likely to suffer due to indoor pollutants. In addition, those who become ill. the number of children with asthma has increased 49% since 1982. It is estimated that one child in five As noted previously, many building owners and man- has asthma. agers responded to the increased energy and utility 2 costs of the 1970s by reducing outside air, and by ª low occupancy of rental space making their buildings tighter with weatherstripping. To make matters worse, maintenance personnel ª lawsuits. sometimes were cut to help pay for the additional energy costs. Even today, some buildings are If you service a building with SBS, what should wrapped with plastic over the outside walls. Many you do? buildings have no provision at all for outside air. In some strip malls, you can see rooftop units without Attempting to correct IAQ problems without under- economizers. A building of this type depends on standing the cause of the problems can be ineffec- opening and closing the front door for ventilation. tive, expensive, and legally catastrophic. However, there are things that a capable HVAC technician can All of these conditions create an indoor environment do when SBS is suspected: in many buildings where fresh air is virtually nonexis- tent. The air is recirculated along with cigarette ª First, ensure that there is sufficient ventilation in smoke and other pollutants. In some cases, bacteria, occupied spaces. Measure and record air flow fungi, and germs grow in the duct system and spread rates. throughout the entire building. There have been extreme instances of “sick” buildings that could not ª Ensure that the HVAC system is clean and free be cleaned up economically, and had to be torn down from chemical or biological contaminants. completely (at great cost, because of the biohazards involved). Both commercial and residential buildings ª Identify potential sources of contaminants, such have been demolished with severe infestations of as building exhausts, internal combustion black mold. exhaust, condensate pans, rodents, etc. Symptoms of poor indoor air quality ª If possible, eliminate all potential sources of the problem, and continue to monitor.

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