Does Having Indoor Plants Improve Air Quality?

January 22, 2021

When you think about air pollution, your thoughts probably go to smog, ozone and other outdoor air pollutants. Most people are shocked to learn that the air in their homes is typically two to five times more polluted than the air in their backyards. If the quality of your Seattle, WA, home’s air concerns you, you may wonder what you can do about it. Someone may have told you that houseplants are a good way to cleanse the indoor air. Before you drive to the nursery and stock up on a trunk full of plants for your home, it’s important to know how those indoor plants affect the air quality in your living space.

What’s in Your Home’s Air?

In the United States, people typically spend 90% of their time indoors. This increases during the winter months of the year. Most of your time will be spent at home, and the particles, vapors and other pollutants in your home’s air will have a big impact on your health, comfort and well-being. Some of the most common indoor air pollutants found in Seattle area homes include radon, volatile organic compounds and combustion gases from burning natural gas.

Dangers of Indoor Air Pollution

Indoor air pollutants can cause irritation to your eyes, nose, throat and skin. When you breathe particles into your lungs, they can trigger an inflammatory process that reduces your ability to respire. If you already have a respiratory disorder, such as asthma or chronic obstructive pulmonary disorder, you may experience difficulty breathing when exposed to poor air quality. Some types of indoor air pollutants, including radon and formaldehyde, are known to cause cancer in people. The Seward Park neighborhood of Seattle and other parts of King, Snohomish and Pierce Counties are known to have high concentrations of radon in the soil, and the gas can seep into the lowest level of your home.

What Plants Have to Do With Indoor Air Quality

You may have heard that indoor plants can pull those pollutants out of your home’s air. Plants respire differently from animals, including humans. They use carbon dioxide and create oxygen as a waste product. They release the oxygen from their cells during a respiratory cycle. This is the opposite of how animals respire.

Laboratory Study of Indoor Plants and Volatile Organic Compounds

Volatile organic compounds are chemicals that can be off-gassed from an item. Some examples of these compounds include methylene chloride, benzene and formaldehyde. Houseplant enthusiasts and natural living proponents have extolled the virtues of houseplants and their ability to remove volatile organic compounds from the indoor air. This opinion comes from a small, limited study that took place in NASA’s laboratories in 1989. In that study, researchers placed 12 varieties of common houseplants into small sealed chambers. Each chamber measured about one cubic foot in volume. They tested popular indoor plants, such as mother-in-law’s tongue, ficus and peace lily. Their measurements found that the plants removed between 10% and 70% of volatile organic compounds from the chambers within 24 hours. However, people don’t live in sealed chambers. The chambers were empty other than the plants. Homes have materials that can be a constant source of volatile organic compounds, and people bring new items into their homes on a regular basis. These new items can be fresh sources of indoor air pollutants.

New Analysis Indoor Plants and Volatile Organic Compounds

There has been little scientific evidence to date that houseplants are able to make a measurable reduction in the concentration of volatile organic compounds in a typical home. In a study published in the Journal of Exposure Science & Environmental Epidemiology, researchers reviewed 196 experiments and 12 studies of volatile organic compounds. The researchers found that in typical household conditions, no houseplants were able to make a noticeable difference in the level of any volatile organic compound.

Recreating the Old Study

Researchers wanted to see if they could recreate NASA’s results from 1989. When they re-ran the experiments, they found that the 12 varieties of houseplants yielded a clean air delivery rate of less than 1%. This meant that the houseplants removed less than 1% of the volatile organic compounds, vapors and other pollutants from the air in real-world conditions.

What These Studies Mean

The scientists showed that while houseplants can remove some volatile organic compounds and other indoor air pollutants, they remove very little of them. You would need to have between 10 and 1,000 houseplants per square meter of space in order to make a measurable difference in the quality of your home’s air. The researchers determined that air purifiers are a much better solution for removing indoor air pollutants compared to houseplants.

What Houseplants Can Do for Your Home

Even if indoor plants can’t remove enough volatile organic compounds to make a big difference in your home’s air quality, there are some benefits of bringing them into your living space. Several scientific studies have shown that indoor plants diversify the microbiome in homes. They have beneficial bacteria that can out-compete harmful bacteria. Houseplants also release some oxygen and remove some carbon dioxide from your home’s air. If you have a tightly sealed home, this may help you breathe easier. There are also many mental health benefits of houseplants. The greenery delivers a sense of calm. Studies have found that including houseplants in living spaces can improve productivity, life satisfaction and mental wellness. The presence of plants may lower anxiety, stress and depression.

Which Houseplants to Choose

You may decide that even a small reduction in volatile organic compound concentrations makes houseplants a good addition to your home. The indoor plants that are the most effective at removing indoor air pollutants include English ivy, bamboo palm, Chinese evergreen, spider plant, peace lily, golden pothos and philodendron. The flowering plants that are the most effective at capturing volatile organic compounds include gerbera daisy, chrysanthemums and flamingo lily. For the best results, the scientists who conducted the studies recommended combining a whole-home air purifier with a collection of these houseplants.

Proper Care of Indoor Plants Impacts Air Quality

If you choose to bring indoor plants into your home, the way you care for them will impact the air quality in your living space. Overwatering is not only bad for most houseplants, but it can also be detrimental to your home’s air quality. Excessive moisture in the potted plant could fuel mold growth. Extra water in the pot could also attract mites, gnats and other insects that are troublesome. Some houseplants produce pretty flowers, but those flowers may release pollen. If you’re allergic to pollen, you may want to reconsider the types of houseplants you choose.

At Brennan Heating & Air Conditioning, we’re the trusted installers of indoor air quality solutions. Seattle homeowners also turn to us for affordable heating and air conditioning maintenance, repair and installation services. Our electric, water heater, air duct cleaning and home energy performance services are designed with your safety, health and comfort in mind. To learn more about the ways indoor plants affect your home’s air quality, get in touch with us at Brennan Heating & Air Conditioning today.

Brennan Heating & Cooling icon