IAQ monitors

CAN WE CLEAR THE AIR?

By Hayley Chandler

Call it Sick Building Syndrome, call it poor indoor air quality; but where do you start to solve the worker complaints that bedevil so many modern buildings?

We’ve almost made it through another winter and for most of us that has meant spending a lot of time indoors. All that time inside can lead to cabin fever, which the Canadian Oxford Dictionary describes as "a condition characterized by lassitude, irritability, anxiety, etc. resulting from long confinement or isolation indoors, especially during the winter." While cabin fever is not something you’re likely to have to address in the workplace, there are illnesses related to indoor air quality that you may have to deal with.

The most common is Sick Building Syndrome (SBS) also called Tight Building Syndrome (TBS). It is not life threatening but it can be difficult to deal with. The symptoms are variable and include headache, fatigue, nausea, dizziness, respiratory problems, dry throat, eye irritation, runny nose, nasal congestion, and/or a loss of concentration. They usually disappear when the afflicted individuals leave the building for a period of time but return when they re-enter it. Often, an exact cause cannot be identified and it is generally believed to be a reaction to low levels of multiple contaminants.

IAQ complaints have increased over the last two decades because of attempts to conserve energy in response to rising energy costs. Buildings are better sealed and ventilation systems bring in outside air and mix it with a percentage of inside air. The air is heated, humidified or cooled and then distributed throughout the building. If the amount of outside air brought into the building is insufficient because of improper design, or if it is reduced in an attempt to reduce heating cost, contaminants start to build up inside.

Indoor pollutant levels have also increased due to growing use of synthetics in building materials and office furniture, the increased reliance on office equipment, which can emit contaminants, and the use of chemical cleaning products. In attempts to lower overhead costs, companies pack as many people as possible into workspaces. These occupants are themselves a source of numerous volatile organic compounds -- such as the residues of dry-cleaning fluids given off by their clothes. In addition, the many grooming products people use, such as hair spray, perfumes and deodorants all contaminate the air.

When you talk about indoor air quality using an office building as an example, "there are probably anywhere from 1,000 to 100,000 different chemicals that are going to be floating around in the air in there," says James LaChance, president of Monitech, a manufacturer of IAQ monitors in Corunna, Ontario. For the most part, those chemicals are going to be at very, very low concentrations.

Air can be monitored in several different ways. Depending on what you’re testing for, you can use detector tubes and pumps, vapour monitoring badges, personal air sampling pumps, direct-reading dust samplers, colormetric tubes, and hand-held or wall-mounted electronic monitors to name a few. But if you don’t know which of the thousands of possible contaminants you’re looking for, conducting a wide range of tests is expensive, time consuming and often ineffective.

Another difficult aspect about solving IAQ problems is that noise, poor lighting, and problems with temperature can all cause discomfort and may be falsely attributed to airborne contaminants. Or affected individuals may be responding to the cumulative effect of a wide variety of irritants.

"IAQ concerns are often unrewarding from the investigator’s point of view and also from the complainant’s point of view because symptoms are nonspecific and sometimes you just can’t measure the presence of some substances that might account for the symptoms," says Greg Naherne, a hygienist and occupational health and safety consultant in Hamilton, Ontario.

The IAQ monitor

Of course, manufacturers earn their livings developing equipment to help us solve such dilemmas. In this case, they created the IAQ monitor, which checks the atmosphere for general air quality.

Rather than attempting to test for all the possible contaminants that might irritate occupants, IAQ monitors measure carbon dioxide (CO2) -- a gas we all exhale -- as an indicator of how well the ventilation system is working. The theory is simple. Because people breathe out carbon dioxide, levels will rise when people enter the workplace. Levels of carbon dioxide will become very high if there is an inadequate supply of outdoor air. While the CO2 could itself be a problem at high levels (see the sidebar on page xx for recommended levels), the fact that levels are up in a given space also indicates that there are ventilation problems; and that means that all those other contaminants of the modern workplace are likely building up, too.

If this is the case and the fresh air intake is increased, the levels of all contaminants should decrease. The IAQ problem could be solved without ever identifying the exact cause. In other words, you can’t easily test for minuscule amounts of thousands of unknown contaminants, but you can test for CO2, and it’s a pretty fair bet that if CO2 is up, so is everything else. "With these general problems, it’s almost always the ventilation system," says LaChance.

Because IAQ investigations are often undertaken to determine the cause of occupants’ discomfort, IAQ monitors also measure two comfort parameters: temperature and relative humidity. (See sidebar on page xx for recommended levels.) Temperature is measured to determine if workers are becoming too hot or too cold throughout the day. When people feel uncomfortable, their sensitivity to other factors is often heightened. If humidity levels are low, people’s nasal passages dry out making them uncomfortable and more susceptible to colds, viruses and flu.

"In Canadian applications, very seldom do you find adequate relative humidity in winter time. It’s much drier in most locations than the recommended 50 per cent relative humidity," says Naherne. "Because if you tried operating your ventilation system at 50 per cent relative humidity, and you have a cold wall you’ll end up with condensation problems." Condensation and high humidity in general can lead to growth of mildew, mold and spores, which, in turn, can produce dangerous air contaminants.

An IAQ monitor measures carbon dioxide, temperature and relative humidity simultaneously and can take measurements automatically at predetermined intervals for a short or long duration. Readings are stored in the device’s memory, which can then be downloaded onto a personal computer for analysis and reporting.

"We first started doing this type of work in the early eighties using individual gas monitors combined with data loggers," recalls Naherne. "So you’d get a continuous read-out for a period of time and load it up onto a data logger and then dump it out. But those were individual instruments -- sometimes a carbon monoxide monitor, sometimes a carbon dioxide monitor, sometimes a temperature and a relative humidity instrument. You’d merge all the data together. Today all of those instruments are combined into one elegant IAQ meter." The monitors range in size from hand-held devices about the size of a large personal cassette player to devices the size of a briefcase.

"IAQ meters can be good because you can record data continuously over a period of time and see what the fluctuations are," Naherne observes. Because contaminant levels can vary greatly throughout the day you might not be able to identify a problem with a single reading or readings of a short duration. By plotting measurements overnight or over a couple of days, you can see what trends occur for more detailed, more useful data.

Additional features

While carbon dioxide, temperature and relative humidity measure the basic indoor air quality, ventilation and comfort parameters recommended by American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE), there are more elaborate models that will also measure a large number of other contaminants and comfort variables. These could include formaldehyde, ozone and volatile organic compounds (VOCs), dust, air movement, lighting and noise.

"A good indoor air quality monitor will give you CO2, temperature, humidity and carbon monoxide (CO)," says LaChance. "I always recommend customers get the CO measurement because pretty much every building today has gas in it and at some point or another everything fails." (See "The Invisible Hazard", Jan/Feb, 1999, page 54.)

When selecting an IAQ monitor, you’ll find that data-logging and software capabilities vary considerably. "Some of them are very simple and limited," LaChance says. Others offer sophisticated features. Some models feature software with the ability to time correlate the data from up to four monitors and present it in one graph. Some monitors can be set up to record data only when the limits you have specified are exceeded. Certain models can be remotely operated from your computer, allowing you to start and stop logging, clear data and view real-time data, without ever touching the instrument. With some software you can create full-colour graphs.

LaChance recommends software that lets you calculate the air exchange rate, scale graphs, add text to the graphs and zoom-in on areas of interest. He suggests software that lets you save and export your files in ASCII format so that you can bring them into your own reports. He suggests that you get minimum, maximum and averages for each of the pieces of data.

LaChance also recommends a start and stop logging feature to allow you to move the monitor from one location to another without having to download it. You stop the logging and start it again in a new location. It breaks the data. When you’re downloading it, you can save the data for different locations in different files. Systems where you get only one file require you to separate the data from different locations, which means you’ve got to know the exact minute that you went from one room to another. "So it’s just one more potential for error there," he says.

The ability to run the instrument overnight and possibly for several days is important, says Naherne. Some models operate from alkaline batteries, rechargeable batteries or AC power. Naherne says battery capacity is important because you may not be able to plug the unit in where you want to monitor. The duration of monitoring offered varies depending on the model, the power source and the sample rate. One model offers 48 hours of datalogging with four AA batteries. Another, when using AC power, provides over 17 days of continuous monitoring capability if 13 variables are saved at a five-minute sample rate; or over six months at a one-hour sample rate.

"Also an optional sampling pump is a nice idea," LaChance says. It draws air across the sensor and provides a constant flow rate. "It provides you with a more accurate, faster responding CO2 measurement under all circumstances. It also allows you the opportunity to do remote sampling." You can place the hose into an air duct or other places you might not be able to put the monitor.

Portability is another consideration. "You want a small unit that’s not going to get in the way of the people," LaChance says. Some IAQ monitors come in tamper-proof cases that can be locked and cabled in place. Theft resistance will be important to buyers who are wary of leaving expensive instruments unattended.

The units also vary in the accuracy of their measurements. When comparing monitors, "the quality of the measurement is one of the biggest differences," says LaChance. "Your temperature and humidity sensor accuracy can range dramatically." Check the product’s literature specs for an accuracy rating. But, according to LaChance, "the best thing is a 30 day personal trial."

"Make sure that the instrumentation is very sturdy, put together very well and that, most important, there’s warranties and there’s service backup by a reputable company that would handle the situation if you need to have it repaired or recalibrated or whatever," says Patricia Pickup-Rose, international sales co-ordinator for Metrosonics, a monitor manufacturer based in Rochester, NY. "You want to make sure that there’s real strong customer support available from the manufacturer or from the company you bought it from."

What’s all this going to cost you? "The average user shouldn’t have to spend any more than $2,500 to get himself into a good datalogging IAQ monitor," says LaChance. Although he also points out that "the average in the industry is probably $4,800." He says the prices are coming down because of new technology. You can also rent monitors for about $300 to $400 per week.

"Most companies do buy their own equipment versus going through a consultant who has the equipment," says Pickup-Rose. "They want to be able to have them [IAQ monitors] available in house." The monitors are useful for long term monitoring of indoor air quality parameters and assessing ventilation-related problems. They can be used to determine compliance with ventilation requirements and codes, and to monitor ventilation rates to avoid IAQ problems.

It’s important to note, however, that monitoring indoor air quality is very different from specific-hazard detection. If you have a potential source of a hazardous contaminant, you should monitor for it as an effort separate from IAQ monitoring. "You have general and you have local problems; the CO2 [monitor] is really only good for general problems," says LaChance. So, for example, if you have reason to suspect that levels of formaldehyde are too high -- you have identified a possible source, in other words -- you should use detector tubes or a monitor designed to measure formaldehyde.

"You go in first and see if you can spot possible sources and possible problem areas so you can focus and determine if this is the right tool to use," advises Naherne. He also cautions that some investigators wave an instrument around and conclude that if everything is fine according to the instrument the problem must be in the complainant’s head. "That’s not a good situation to get into."

Indoor air quality remains one of the more difficult areas of building management, especially once there have been complaints from workers. You may never be able to track down and fix a single cause -- simply because IAQ problems are so complex and nebulous. But adequate ventilation, as measured and confirmed by an IAQ monitor, are the big first step in bringing workers up to their comfort level.

Hayley Chandler is associate editor of safety purchasing for ohs canada.

SIDEBAR

Standards and Guidelines

The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) has established ventilation rates based on acceptable carbon dioxide levels being maintained below 1,000 parts per million (ppm). The recommended temperature range is 20-24 C in winter and 22-26 C in summer. ASHRAE has determined that when relative humidity levels are 50-70 per cent, less than 10 per cent of building occupants are dissatisfied. The following standards are widely used:

* Ventilation for Acceptable Indoor Air Quality. (ANSI/ASHRAE Standard; 62a-1991) Atlanta, ASHRAE, 1996.

* Thermal Environmental Conditions for Human Occupancy: An American National Standard. (ANSI/ASHRAE Standard; 55a-1995) Atlanta: ASHRAE, 1995.

The American Conference of Governmental Industrial Hygienists (ACGIH) time-weighted average exposure limit (TWA) for CO2, as an air contaminant in its own right, as opposed to its role as an indicator of inadequate ventilation, is 5,000 ppm. This would normally occur only in workplaces in which there was a source of CO2 other than the exhaled breath of workers.

Canadian documents that provide guidance on managing IAQ include the following:

* Indoor Air Quality: Health and Safety Guide, published by the Canadian Centre for Occupational Health and Safety (CCOHS) 1998. Copies are available for $10 plus GST and may be ordered by contacting Marketing, Sales and Communications, CCOHS, 250 Main Street East, Hamilton, ON. L8N 1H6 Tel. 905/570-8094 or 800/668-4284 Fax 905/572-2206, E-mail: custserv@ccohs.ca

* Z204-94 Guideline for Managing Indoor Air Quality in Office Buildings, published by the Canadian Standards Association (CSA) 1994. To order contact the CSA at 178 Rexdale, ON. M9W 1R3.

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