Could air purifying plants improve your indoor air quality in Shanghai?

As we spend most of our time indoors, it is critical to keep your indoor air clean.

Apart from outdoor pollution, other pollutants can affect indoor air quality, such as emissions from furniture and building materials, cooking and heating gas, plastics and detergents etc.

If we close windows and doors to prevent outdoor pollution from entering, or to save energy, it is even more critical to ensure indoor air is purified.

One of the most effective air pollution solutions is using air purifiers in your home, but a cheaper, if not so effective, solution is to use air purifying plants.

There are several plant and flower markets in Shanghai where you can find hundreds, if not thousands, of varieties of flowers and plants. These markets house many vendors under one roof, so you can usually get good prices just by doing comparison shopping, even if your bargaining skills aren’t so great.

The vendors will arrange delivery, sometimes included for free depending on the amount of your purchase. In case you don’t have a green thumb, there are also some vendors that will rent you plants, including a monthly maintenance service, to make sure they are watered correctly.

How do Plants Clean the Air?

Besides breathing in carbon dioxide and breathing out oxygen, air purifying plants also absorb other toxins.

There is some controversy about how effectively they do this, with the California Environmental Protection Agency stating in a 2005 report on Air Cleaning Devices for the home that “Houseplants do not effectively remove indoor air pollutants.

“One researcher has reported that certain air purifying plants can remove significant amounts of indoor air pollutants. However, six subsequent reviews, and a study in office buildings and portable office buildings, indicated that houseplants have very little, if any, effect on indoor pollutant levels.

“Small effects might occur, but only with an unreasonably large number of houseplants present, which could easily cause other indoor pollution problems such as excess moisture.” Read their full report here.

There have been, however, several studies that do show plants have many benefits, including purifying our indoor air.

NASA Report by Dr B.C. Wolverton

The best-known study of air purifying plants was done by NASA and Dr. B.C. Wolverton in the 1970s and 80s. This study was carried out to find ways to clean air in orbiting space stations, where astronauts would be confined for long periods of time.

Dr. Wolverton went on to do many more of his own studies and published several books on the effectiveness of plants in purifying air.

The NASA study focused on 3 common toxins found in indoor air:

  1. Formaldehyde, which can be emitted by particle board or pressed wood products, used in manufacturing of office furniture, grocery bags, waxed papers, facial tissues and paper towels, adhesive binders in floor coverings, carpet backings and permanent-press clothes, heating and cooking fuels like natural gas, kerosene, and cigarette smoke.
  2. Benzene, which can be emitted by gasoline, inks, oils, paints, plastics, and rubber, detergents, pharmaceuticals, and dyes.
  3. Trichloroethylene, which can be emitted by printing inks, paints, lacquers, varnishes, and adhesives.

The results of the study showed that some air purifying plants can remove up to 87 percent of some air pollutants within 24 hours. Based on their studies, NASA recommended the use of 15 to 18 good-sized houseplants in a 170 m2 home or office.

Dr. B.C. Wolverton’s list of the 50 most effective air purifying plants was published in his book ‘How to Grow Fresh Air‘.

Other Studies On Air Purifying Plants

A separate study from the Pennsylvania State University published in an issue of the American Society of Horticultural Science’s journal HortTechnology revealed that three common houseplants; snake plant, spider plant, and golden pothos, all showed an ability to reduce ozone, another air pollutant which is becoming a serious issue in Shanghai.

Air purifying plants are known to be very adaptable to their environment, as their air purifying capability increases over time. They learn to convert more of the toxic particles in their new environment into their own food source.

The NASA study also showed that the roots and exposed soil plays a big part in absorbing the toxins, so lower lying leaves and branches should be removed to ensure maximum contact with the air.

Some plants, however, can also be toxic, so you should check the list for non-toxic safe air-purifying plants if you have pets or young children.

Reducing Mold and Regulating Indoor Moisture

Another study published by Dr. Wolverton in 1996 in the Journal of the Mississippi Academy of Science showed that rooms with air purifying plants have 50 to 60 percent less airborne microbes, such as mold spores and bacteria, than similar rooms without plants.

Plants do this partly by reducing humidity levels indoors down to between 40 and 60 percent, the ideal level for humans, thereby helping to prevent mold growth.

Although some people recommend removing plants to reduce allergies, a reduction in mold spores and bacteria in the air could actually have a great benefit to allergy sufferers.

Another way air purifying plants reduce microbes is by releasing negative ions. In an article published in the Journal of Environmental Horticulture, also in 1996, Dr. Lohr, found that houseplants can reduce human stress and increase productivity by releasing negative ions, which have been known for many years to have health benefits to humans.

Ions can improve people’s mood, alleviate depression, and help to cure seasonal affective disorder (SAD, or winter depression).

Ions are charged particles in the air which can be produced by UV light, airflow friction, lighting, falling water and plants. As air purifying plants emit water vapors they produce negative ions. Many products found indoors such as plastics have a positive static charge that consumes large amounts of negative ions.

In another study (Atmospheric Environment, 1996, 30(14): 2565-2568) Dr. Lohr also showed that houseplants could reduce dust levels in a computer room by 20 percent, also helping allergy sufferers.

Air Purifying Plants Improve Work Efficiency

In a study published in 2011 in the Journal of Environmental Psychology, scientists showed that air purifying plants placed in an office helped to boost the attention span of office workers, showing that greenery has regenerative effects for directed attention.

There is a report extensively distributed around Chinese Social media sites promoting the effectiveness of 14 plants for their air purifying attributes. This report does not list who did the study, and just refers to ‘experts’.

Some of the same or similar plants can be found on the NASA list. You can find the list with a rough translation below.

Caojiadu Flower Market Shanghai
Caojiadu Flower and Bird Market in Shanghai

Flower and Plant Markets in Shanghai

Flower and plant market in Shanghai:

  • Cao Jia Du Plant, Flower & Bird Market
    (The largest in Shanghai, but this was relocated at the end of 2017)
  • Hongqiao Bird & Flower Market
    Add: 718 Hongjing Lu, near Hongsong Lu,
    Open till 18:00
  • Yongjia Flower Market
    Add: 406 Shaanxi Nanlu, near Yongjia Lu
    Open till 18:00
  • Pudong Flower Market
    No. 620 Pujian Lu, near YangGao Nan Lu
  • Meiyuan Bird and Flower Market
    49 Fushan Lu, Pudong New Area
  • Shanghai Metropolis Flower Market
    Xizang Zhong Lu, behind Shanghai No 1 Department Store
  • Jingwen Flower Market
    225 Shaanxi Nan Lu

Best Air Purifying Plants List

Chinese report on the 14 most effective air purifying plants with their Chinese language names:

  • Dripping Guanyin (Dīshuǐ guānyīn):
    Can clear dust from air. However, it can be toxic, so make sure animals and children don’t eat it.
  • Gentleman orchid Clivia (君子兰: Jūnzǐlán):
    Very effective in absorbing large amounts of air and releasing oxygen, even at night.
  • Rubber tree (Rubber tree: Xiàngpí shù):
    Good for eliminating many harmful substances including carbon monoxide, carbon dioxide, hydrogen fluoride and other harmful gases as well as remove small particulate matter so reducing indoor dust.
  • Asparagus (文竹 Wén zhú):
    The eradication of bacteria and virus protection umbrella. Asparagus’s aroma has antibacterial ingredients, so can clear the air of bacteria and viruses. The roots are sometimes used as medicine.
  • Silver Queen – Chinese Evergreen (银皇后: Yín huánghòu):
    Very suitable for dark rooms with poor it can clean air with high concentrations of pollutants.
  • Adiantum fern (Tiě xiàn jué):
    Good at absorbing formaldehyde (20 micrograms per hour). In addition, it can also inhibit the release of of xylene and toluene from computer monitors and printers.
  • Spider plants (Chlorophytum: Diàolán):
    Effective in absorbing high amounts of carbon monoxide and formaldehyde under low lighting. Can also decompose benzene and nicotine from cigarette smoke. Known as the green indoor air purifier.
  • Aloe Vera (Aloe: Lúhuì):
    Can absorb formaldehyde, carbon dioxide, sulfur dioxide, carbon monoxide and other harmful substances. Can kill harmful microorganisms in the air and can absorb dust. Spots will appear on Aloe leaves when the air is hazardous, so more plants should be added.
  • Bamboo Palm (棕竹: Zōng zhú):
    Good at eliminating heavy metal pollution, carbon dioxide and sulfur dioxide. As a plant with large leaf foliage its biggest feature is ability to digest large amounts of carbon dioxide and produce oxygen.
  • Monstera (Monstere: Guī bèi zhú:
    Evergreen vines. Clears formaldehyde better than other plants, as well as is good at absorbing carbon dioxide and releasing oxygen during the night.
  • Ivy (Ivy: Cháng chūnténg):
    The champion for absorbing formaldehyde. Ivy can also absorb benzene. Supposedly, 2-3 pots of Ivy in a 10 m2 room is enough to purify the air and adsorb small particulate dust.
  • Lucky Bamboo (富贵竹: Fùguì zhú):
    Suitable for the bedroom. Effective in cleaning the air in rooms with poor ventilation. It also has a disinfectant function.
  • Pachira (Fācái shù):
    Evergreen, through photosynthesis can absorb toxic gas and release oxygen. Effective in absorbing carbon monoxide and carbon dioxide, as well as smoke from tobacco.
  • Cactus (Cactus: Xiānrénzhǎng):
    Has a strong anti-inflammatory sterilization role in the fight against pollution. The cactus is the best plants to reduce electromagnetic radiation. In addition cactus absorb carbon dioxide and release oxygen at night so conducive for sleep.

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