September 2004

PLANT ADVANTAGE

By Lydia Dumyn

Odds are that if you discovered a fuzzy, green sandwich in the back of your desk drawer, you’d quickly realize its days as a healthy snack were long gone and toss it in the trash. But what about that mould in the soggy soil of your over-watered, potted plant? Research suggests that well-maintained and appropriately placed office plants can contribute to healthier, happier and harder-working employees. As part of a two-year study, Professor Tove Fjeld of the Agricultural University in Oslo, Norway found that, following the introduction of plants, reports of fatigue dropped 20 per cent, headaches fell 45 per cent, dry and sore throats decreased 30 per cent, and coughs decreased 40 per cent. As well, 25 per cent of employees with dry facial skin reported improvements. But neglecting those office plants can quickly transform that once healthful greenery into something that resembles a failed science experiment. At this stage, says Dr. David Miller, a fungal metabolites expert at Carleton University in Ottawa, all benefits have been lost and those same plants may now pose a health hazard. “People might not think that in a public space, a ‘compost heap’ is a problem, but it is,” Dr. Miller says. The Canadian Lung Association reports that one in five people in this country suffers from respiratory problems and more than two million individuals have asthma. Most people will not have adverse reactions and display symptoms, says Dr. Susan Mary Tarlo, a specialist in occupational lung disease and asthma at the University of Toronto’s Department of Public Health. Dr. Tarlo notes, however, that “people who have asthma and are allergic to mould may have a flare-up with increased coughing, wheezing, shortness of breath and tightness in the chest. [They] may get a stuffy, runny nose, sneezing, itchy, red and watery eyes.”

Here today, gone tomorrow

Other common side effects include headaches and irritability. These effects, she continues, “can be very distracting, not to mention dangerous.”

Respiratory problems can both worsen or develop as a result of inhaling contaminants associated with paint, ink, floors, and moulds in plants, Dr. Tarlo says. There aren’t really any long-term effects, she says, noting that removing a contaminant usually causes side effects to disappear.

The type of moulds commonly found in over-watered plant soil are A. fumigatus, Aspergillus niger and Aspergilus flavus. Countless other airborne mould spores may float in through opened doors and windows, taking hold in moist environments, Dr. Tarlo explains.

Moulds are among the pollutants that can contribute to sick building syndrome (SBS), where air quality in sealed, energy-efficient buildings deteriorates because of the toxins produced there.

Indoor air quality (IAQ) has been a big concern for the past 30 years, since phrases like “energy crisis” and “oil prices” were coined, says Dr. Michael Dixon, director of the Controlled Environment Systems research program at the University of Guelph in southwestern Ontario.

Beyond respiratory

There may be many physiological and psychological consequences to breathing mould spores, such as eye and ear infections, severe nausea and even cancer, Dr. Dixon contends. Health risks reach beyond individuals with pre-existing respiratory ailments, he says, and normally healthy people can develop complications to fungal pathogens whether or not they are susceptible.

“Construction technology has been modified to seal up buildings to conserve energy — and money. North Americans spend 90 per cent of their time in these controlled or semi- controlled environments, trapped with volatile organic compounds (VOCs),” Dr. Dixon says.

VOCs common to office settings — such as methyl-ethyl ketones (like xylene) from paints, or formaldehyde from building materials — are present in relatively trace quantities, he says. What is not typically considered or well-understood is the effect of hundreds of VOCs, all in trace parts-per-billion levels, “and being exposed to that soup indefinitely.”

The three most common office air toxins can be moderated by certain plants, says M.J. Gilhooley, a spokesperson for Plants At Work. 
• Azaleas, spider plants, bamboo palms, poinsettias and chrysanthemums are not only pleasing to the eye, they also provide a defence against formaldehyde, found in foam insulation, plywood, clothes, carpets, furniture, paper goods and household cleaners.
• Gerbera daisies, marginata, chrysanthemums, warnecki and the peace lily can be used to reduce benzene levels, commonly emitted from inks, oils, synthetic fibres, detergents, plastics, tobacco smoke and gasoline. 
• These plants can also diminish the presence of the third most common office pollutant, trichloroethylene, which is found in inks, dry-cleaning, paint, varnishes and adhesives.

Dr. Dixon is quick to dispel the myth that plants “clean” the air. What they do is “provide a component of the ecosystem that houses the microbial systems that do ‘eat’ the air,” he says. Various plants, along with the microbes in the plant’s aqueous system and root zone, absorb almost everything in the air and metabolize it.

In his research of sealed chambers with various indoor pollutants, Dr. Bill Wolverton, an expert in the use of natural processes for environmental pollution control and author of How To Grow Fresh Air, found in research he conducted for the National Aeronautics and Space Administration (NASA) that all plants tested were effective in reducing toxin levels. For optimal benefits, however, Dr. Wolverton recommends selecting leafier plants and combining different plants for their individual abilities to filter different toxins.

Plant leaves can absorb certain organic chemicals and destroy these chemicals by a process called “metabolic breakdown”, Wolverton Environmental Services, Inc. reports on its website. “When plants transpire water vapour from their leaves, they pull air down around their roots. This supplies their root microbes with oxygen. The root microbes also use other substances in the room air, such as toxic chemicals, as a source of food and energy.”

Increasing soil volume increases the plant’s rate of absorption and plants grow more efficient at “cleaning” the air. “Microbes, such as bacteria, can rapidly adapt to a chemical contaminant by producing new colonies that are resistant to the chemical. As a result, they become more effective the longer they are exposed to the chemical,” the information says.

Dr. Dixon is involved in various plant research projects, including the CLER, or the Canada Life Environment Room. He tracks the progress of a breathing wall — an indoor ecosystem designed to do for indoor air what earth’s ecosystem does for all air. David House, vice-president of development for GWL Realty Advisors, the asset manager and development party responsible for the Canada Life complex, describes the breathing wall as “a slice of a Costa Rican rain forest.”

Keeping SBS at bay

The airtight building features a high-quality exterior wall and, therefore, a very low air leakage rate, House says. If not properly ventilated, he says “it would suffer quite quickly from sick building syndrome. So an attempt was made not only to ventilate it to a very high standard, but also to look for technologies which could help to improve the air quality inside a relatively tightly sealed building.”

A little green, House says, seems to go a long way when it comes to employee satisfaction. “There’s been a fairly significant demand for the room to be opened at common periods — early in the morning, lunch time and after work, so that people can take some time to spend in there, perceptually because they seem to feel better. We’re not yet sure whether it’s the air quality, the humidity, the visual impact of the plants. More research needs to be done to really discern in an effective way what the response is really to. But it is regarded as a space where people generally tend to feel better, when they’re congested, have colds, asthma and other respiratory issues. And clearly it’s a space that people find visually interesting.”

Installing a breathing wall may not be practical for every space and budget. But Dr. Dixon maintains that office workers can reap similar benefits from potted plants. The rule of thumb is “a floor area of 100 square metres needs a bio-filter of one square metre,” he says.

This is fairly standard no matter what type of plant is used, he explains, although, naturally, even plants of the same species are different and how they are maintained must be taken into account.

It is important to remember, Wolverton Environmental Services reports, that “the efficiency of plants or a filtering device decreases as the concentration of chemicals in the air decreases.”

If plants are to be part of the office décor, proper maintenance can sometimes be done in- house; other times, it’s advisable to call in the professionals. By keeping the soil clean and dry, the potential mould source can be eliminated, says Brian Stocks, air quality manager for the Canadian Lung Association. A few potted plants can be easily maintained in-house by taking them outside, tilling their soil and letting them dry out, Stocks says.

Get rid of the compost by picking out the dead leaves, advises Christine Skene, owner of Southern Tropic of Plants, an office plant maintenance provider near Winnipeg. “Plants need more than just a bit of water. They need to be kept clean, trimmed and free of dead debris.”

It’s also important not to over-water office plants. If the plant’s pot becomes a pool, says Joanne Young, president of Greenery Office Interiors Ltd. in Calgary, the conditions are receptive for mould growth. “Over-watering is a bigger problem than under-watering. If you under-water, the plant will just eventually dry up and die,” says Young.

Of course, Young adds, there are many factors to consider in an office environment. Lighting differs according to location; heating and cooling systems may come into play. So each time plant technicians visit an office, they must consider office conditions to determine watering requirements. “When you don’t have somebody that’s trained, they’ll go around and pour to their heart’s content and think, ‘I don’t need to do this again for another couple of weeks,’” Young says.

A plant that is starting to droop is the surest sign that owners are guilty of over-watering, she adds. “Usually, the stock of the plant will start getting really soft and wrinkled, and really look like it’s unable to stand on its own.”

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