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Can green plants purify indoor air?Scientists tell you: when it comes to growing green plants, the most important thing is to be happy-IT HOME



This article comes from the WeChat public account:SF Chinese (ID: kexuejiaodian)text: Ceri Perkins, translation: Mei Lin, editor: Zhao Jiaming

Studies have shown that the concentration of harmful substances indoors can reach more than 5 times that outdoors.

We often see content such as “Green plants must not be placed casually”, “Help stickers! Several kinds of ‘detoxification’ plants that most people don’t know”, and some health media even list “10 kinds of the strongest air purification ability green plants”.

In addition, in the past two years, due to the impact of the epidemic, we spend more time indoors. Many friends have paid more attention to indoor air quality and started to put green plants everywhere in their homes.

So, are there any benefits to having green plants at home? Is there any scientific basis for this statement?

What exactly do green plants purify?

Only by knowing yourself and the enemy can you be victorious in a hundred battles.

Before answering whether green plants can purify the air, we must first know who the “enemy” of green plants is.

According to NASA’s research, the main effect of green plant purification is “Volatile Organic Compounds“(volatile organic compounds, abbreviated as VOCs) harmful substances.

The well-known formaldehyde is a typical representative of VOCs.

According to the definition of the US Federal Environmental Protection Agency, among indoor air pollutants, except carbon monoxide, carbon dioxide, carbonic acid, metal carbides, metal carbonates and ammonium carbonate, all carbon compounds that can participate in atmospheric photochemical reactions are VOCs.

Friends may think that these substances seem to have been seen in middle school chemistry textbooks, and they seem to be no big deal.

You can think wrong, according to the survey, the deaths of more than 20 million people around the world are directly related to them.

Even if there is no death, according to some research institutions, when the concentration of VOCs is small, people may feel sick.

If the concentration of indoor VOCs continues to rise, it will cause headaches, symptoms of neurotoxicity such as nausea and memory impairment, and even induce serious diseases such as tumors, especially some closed and narrow indoor environments are full of risks.

Cooking is one of the main sources of indoor VOCs. In Guatemala, such traditional cooking produces a lot of VOCs. (Image credit: gringologue/Flickr)

works a bit but not much

Sources of VOCs can be found everywhere in our homes – furniture, paint, plastics, wood floors, kitchens, etc. Now that we already know, the enemy of indoor green plants is mainly VOCs.

Can green plants really purify VOCs in the air?

Unfortunately, it works, but not by much.

According to NASA research from 1989, green plants can indeed purify indoor air (in a closed environment).

Scientists have found that some species of greenery can remove as much as 70% of the experimental VOCs after 24 hours.

But this does not mean that in real indoor environments (such as our homes or office environments), green plants can really effectively purify the air.

A scientific review published in 2019 pointed out that NASA has done 11 more studies over the past few decades: In a closed environment, scientists blow VOCs to green plants with fans, and then collect them with carbon filters to measure the effect of green plants on VOCs purification level.

In other words, such an experimental setting does not exist in our real life.After all, experimental research has some “special settings”, which are still somewhat different from our actual life.

Are green plants really useless?

You may have noticed that in these NASA studies, the experiments were conducted in a closed environment – green plants were put into small airtight containers.

In the place where we work and live, such a sealed environment cannot exist.

In other words, NASA’s experimental results cannot be “replicated” in real life.

But it cannot be said that placing green plants indoors has no effect at all. According to estimates by NASA researchers,If you can place 10 to 1,000 green plants on every square meter of ground in your home, maybe the green plants can purify VOCs at a rate that can catch up with the rate of indoor and outdoor air circulation through gas exchange..

Because in the home and work place, the air can always circulate indoors and outdoors, so that air pollutants can continue to enter the room.

Although green plants do not do much to clean indoor air, studies have found that green plants have some other value.

For example, green plants can adjust the indoor humidity; indoors, placing green plants can improve people’s mood, thereby improving work efficiency; green plants can also beautify the indoor environment. If you still want to improve your indoor air quality, it is best to buy an air purifier with better filtration performance.

In addition, if the outdoor air quality is good in your area, you can also open the windows appropriately for ventilation.

Green plants complete gas exchange through the stomata on the leaves. For example, in photosynthesis, carbon dioxide in the air enters the leaves through the stomata, and the oxygen produced by the plant is discharged into the air through the stomata. Along with the gas exchange, some air pollutants (such as VOCs) also enter the blade through the stomata. Green plants purify the air in this way. (Image credit: H McKenna)

Green plants cause carbon dioxide poisoning?

As we mentioned earlier, green plants purify the air through gas exchange.

Seeing this, some friends may have to worry: respiration is a process of gas exchange among green plants. During respiration, green plants will release carbon dioxide. If you put a lot of green plants in the bedroom, when you sleep at night, you will not be able to breathe. It’s carbon dioxide poisoning.

In fact, there is no need to worry at all, this is just a “rumor”.

In fact, when you turn off the lights and go to sleep, the photosynthesis of green plants almost stops due to the lack of energy from the light source, but the respiration is always going on.

Green plants do continue to release carbon dioxide through respiration.

However, there is nothing wrong with that. Because the size of green plants determines how much carbon dioxide they release.

Studies have shown that all kinds of green plants are so small that they emit far less carbon dioxide than human breath.

Therefore, we don’t have to worry about carbon dioxide poisoning caused by placing green plants in the bedroom. After all, we are not “poisoned” by the carbon dioxide we exhale.

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