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Mother-in-law's Tongue

Photo: Wikimedia Commons/Martin Olsson

Indoor air quality is an increasing concern among safety managers and public health professionals alike, as polluted air in homes and workplaces is often more dangerous to breathe than the air outside. Indoor air often contains pollutants such as formaldehyde (a known carcinogen), benzene, trichloroethylene, dusts and particles that can cause respiratory issues and some serious health problems.

Many of these pollutants come from the off gassing of building materials and furniture, work processes and even the outdoors. Interestingly, newer, environmentally friendly buildings sometimes pose greater indoor air quality hazards than their older counterparts. The buildings leak less air so they’re more energy efficient. This also means that if these buildings aren’t designed for proper air circulation between inside and outside, pollutants can build up indoors.

In 1989, NASA and the Associated Landscape Contractors of America (ALCA) published a study examining whether tropical plants could improve indoor air quality for astronauts in space. The study was limited to a laboratory setting, but its findings might have some practical applications for enclosed work environments. The study found many typical houseplants could remove formaldehyde, benzene and trichloroethylene from the air.

Air Pollution

Listen to our short podcast about indoor air quality hazards.

In the real world—rather than in a contained space in a lab—plants might not be able to clean the air to the same extent that NASA found. The EPA, for example, doesn’t endorse the study. More recent studies such as one performed at the University of Georgia, however, have found plants can reduce levels of VOCs. One of the study’s authors points out that more research is still necessary to determine houseplants’ full potential as air purifiers, though.

Another experimental project in India (described in a TED Talk) sought to improve air quality in an office building and used three types of houseplants (areca palms, snake plants and money plants) to clean the air. According to the researcher who presented the experiment at a TED conference, the project has been very successful at improving air quality and health for the building’s occupants.

So what does this mean for business owners and safety managers? It could mean putting some potted plants throughout the workplace—in offices, break rooms, hallways and any other areas where they won’t get in the way of employees doing their jobs—might help keep the air a little cleaner.

Types of Plants That May Improve Air Quality

Houseplant

Peace lilies can tolerate low-light conditions. Photo: Wikimedia Commons/UshaJ

Generally, tropical plants can remove pollutants from the air most effectively. This is because they perform photosynthesis most efficiently, allowing them to absorb gasses more quickly. NASA tested many plants, and some proved more effective at removing certain gasses than others. A ficus, for example, removed more formaldehyde and benzene than trichloroethylene.

If your workplace has few windows and little natural light, you’ll want a low-maintenance plant that can survive in low-light conditions. Common low-light plants that can improve indoor air quality include the golden pothos (also called devil’s ivy), the snake plant (also called mother-in-law’s tongue), peace lilies and Chinese evergreens.

Houseplant

Spider plants need medium light levels. Photo: Wikimedia Commons/Mokkie

For workplaces with some light, philodendrons, kentia palms, dragon trees, spider plants and bamboo palms would work well.

If you’re lucky enough to have plenty of light in your workplace, English ivy, ficuses and areca palms are good choices. 

The studies that have found that plants have a notable effect on air quality were performed in confined spaces, so keep in mind that large workspaces would potentially need many plants to have a similar effect. The initial NASA study from the eighties suggested that to improve the air quality of an 1,800 square foot house, the occupants would need to have between 15 and 18 houseplants in six to eight-inch diameter pots.

Houseplant

Areca palms like lots of light. Photo: Wikimedia Commons/Mokkie

If you do bring plants into the workplace or you encourage your employees to do so, make sure they are properly cared for. Plants that are overwatered can rot, which can have a negative impact on air quality. In general, you should water plants once per week. Check the soil to see whether it is dry and needs watering.

Other Benefits of Workplace Plants

In addition to potentially removing pollutants from and adding oxygen to indoor air, plants provide other benefits as well.

Potted plants can increase humidity levels, making the air more comfortable to breathe and helping prevent respiratory problems, reports U-T San Diego.

Some studies have also found plants have a positive impact on people’s moods and potentially on their work. Plants may reduce stress levels. One study even found the presence of plants improved a person’s ability to maintain his or her attention while performing a task, according to Scientific American.

Improve Indoor Air Quality

Air Circulation

Control the air circulation in your building.

Plants may help keep the quality of the air in your workplace high. You should also take practical steps to improve air quality in other ways, too.

First, make sure your building’s HVAC system is well maintained. It is responsible for circulating air and maintaining the air at a comfortable temperature and humidity level.

You can also keep the building at a slightly positive pressure (so air flows out), ventilate areas that are being cleaned, prevent dust from building up on surfaces and encourage workers not to wear strong perfumes.

For more information about improving the air quality in your building, read Indoor Air Quality at Work Matters.