April 28, 2005
WSU study says plants are good for us
It's no placebo effect, plants make your healthier, happier and more productive.
By VIRGINIA I. LOHR
Many people think they feel better in places with plants. Some think this is just because of the placebo effect if you think plants work, then you'll subconsciously make yourself better. What are the facts? Should you invest in plants?
At Washington State University, we have used double-blind studies to examine the impacts of plants. We have documented effects of interior plants on air quality, well-being, productivity and pain perception.
We have also explored the impacts of trees on people's well-being and the impacts of childhood contact with nature on adult attitudes towards trees in urban spaces. During the past two decades, many researchers, including those in my lab, have documented many benefits from plants, including these:
- Healthier indoor air. Plants reduce pollutants, such as formaldehyde and carbon monoxide. Plants can raise the relative humidity from levels below what is recommended for human health and building performance to levels within the recommended range. Dust accumulation on surfaces is also lower when plants are present.
- Reduced stress. Blood pressure and muscle tension are lower when people are around plants, both indoors and outdoors. Stress is reduced when people have window views of plants and gardens. People performing stressful tasks recover from that stress more quickly and completely with plants in the room where they are working. Walking in gardens is particularly beneficial.
- Better health. When stress is lower, stress-related illnesses including headaches and backaches are fewer. Improved air quality results in fewer respiratory and skin problems. Pain perception is also reduced when plants are present, so people feel better.
- Improved productivity. Productivity on repetitive tasks is higher when performed with plants present. Even cognitive capacity has been shown to be higher in the presence of plants.
- Reduced mental fatigue. Mental fatigue, which is increasingly common with the constant intrusions from e-mail and cell phones, is lower when plants are present. People are more attentive when they are in environments with plants.
- Enhanced moods. People are happier and feel friendlier when plants are present. They also are less sad when plants and trees are nearby.
- Better employee morale. People recognize that putting plants in their workspaces and creating places to relax and exercise outdoors around plants show that their employers are concerned with their health and well-being. Satisfaction with spaces is higher when plants are present.
- Reduced absenteeism. When employees are healthier, less stressed and happier, they take fewer sick days.
- Less violence. Rates of physical violence are lower when people are in spaces with plants than when they are in stark surroundings.
- Reduced energy costs. When plants are appropriately placed around buildings, both heating and cooling costs can be reduced. Proper plant placement can even reduce snow removal costs in cold climates!
Benefits such as these come from having interior plants and from landscaped areas outside. Green roofs with seating areas also contribute to these effects.
To get the most from the plants, they must be healthy and well-maintained. With all of these positives, why not try it?
Virginia I. Lohr is a professor in the Department of Horticulture at Washington State University.
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