How do Plants Really Purify the Air? Research vs Real life


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Having plants in the home is a known staple in every household. Plants bring beauty and style to any decor and adds an accent of contrasting color which soothes the mind and most importantly, improves the air quality by purifying the air in the room.

Plants purify the air through photosynthesis. The plant absorbs carbon dioxide through its leaves where a chemical reaction occurs with chlorophyll in the presence of light which produces glucose (food for plants) and oxygen which is released back into the air.

Photosynthesis

Our homes are made up of many different materials including paint, gypsum and plastics which when put together can create the most stunning decor in our living spaces.

But having these materials in our homes may come at a cost. They all have been found to release small amounts of chemicals into the air we breathe. Some of which are toxic and can affect our health and wellbeing. 

This is where plants come into play. They have been found to have air purifying properties just by carrying out their everyday functions. 

In this article we are going to explain how plants purify the air by removing harmful compounds, along with other beneficial aspects, and the effects of how air flow can aid in the reduction of pollutants.

Plants and VOC bar chart

Air Cleaning Benefits of Plants

Plants clean the air within our living space by “breathing” in the air via their stomata, found on the underside of their leaves, and pores in their roots. 

Harmful compounds such as VOCs (Volatile Organic Compounds) are produced by various materials in our home and offices which are then filtered by plants which inturn releases oxygen into the air we breathe.

Some of these VOCs are benzene, formaldehyde, trichloroethylene, xylene and toluene, which are not noticeable to humans in small amounts.

There are also studies which indicate that plant-filled rooms contain 50 to 60 percent fewer airborne molds and bacteria than rooms without plants.

Plants in an experiment

Here we list the benefits of having plants in our living spaces :-

1. Reduces VOC’s in the air

Plants can remove Volatile Organic Compounds from the air according to a 1989 report from NASA which placed plants in a controlled environment with different VOCs such as Benzene, Trichloroethylene and Formaldehyde. 

An additional experiment published by the American Society of horticultural science (ASHC) in August 2009 which Screened Indoor Plants for Volatile Organic Pollutant Removal Efficiency [Google Scholar], showed that indoor plants can and do remove VOCs from the air.

Both experiments showed that over a period of time, the plants and potted soil in the experiment had the ability to significantly reduce the amount of toxic chemicals in the air.

However, these experiments did not take into consideration the quantity of plants it would require to produce similar results in a real life situation, let’s say in a small room, which we will discuss later in this article.

What the experiment did prove is that plants actually do remove VOCs.

This can be added to the other benefits of having plants in a room. 

Even if the VOC removing capacity it actually has in a real life scenario, is small.

The results from the 2009 experiment is shown below which illustrates (out of the 28 plants tested) the 12 plants which performed better in removing VOCs

Plants and Volatile organic compounds

2. Reduces Carbon Dioxide concentrations

Plants remove carbon dioxide through photosynthesis whereby, 

The plant absorbs carbon dioxide through its leaves where a chemical reaction occurs with chlorophyll in the presence of light which produces glucose (food for plants) and oxygen which is released back into the air.

It is known that the exposure to carbon dioxide can produce a variety of health effects in humans which includes headaches, tiredness and dizziness. 

Within an enclosed room such as a bedroom or basement, carbon dioxide levels can build up over time if it isn’t being removed by plants or being replaced by fresh air.

As a result, when it comes to reducing carbon dioxide levels plants can definitely be beneficial within our living spaces.

3. Increases Oxygen

Plants will increase the amount of oxygen in a room through photosynthesis. 

For this reason, plants are being used by NASA and other spaces agencies to help produce fresh oxygen and support life.

In the article produced by NASA, they explained that they are developing an inflatable greenhouse that could produce oxygen on Mars and feed astronauts, which shows the importance of plants within our living spaces. 

Additionally, it has been shown that increasing the oxygen levels in a room improves one’s health by improving healing, vision, mental clarity and also boosting your immune system which also helps in fighting off cancer cells.

Humidity plants create

4. Increases Humidity

Humidity is a measure of the amount of water vapor in the air.

Plants increase the humidity in a room through a process called evapotranspiration, which is the sum of both evaporation from the plant and transpiration. 

We already know evaporation is the process by which water changes from a liquid to a gas or vapor.

So, transpiration is when plants lose water from their leaves by the capillary movement of water from the soil via the xylem to the leaves where it participates in photosynthesis and is then released through the stomata. 

This process also accounts for what may people deem as “sweat” and would therefore explain the phenomenon of why plants sweat and accumulate water at the leaves.

A good example of evapotranspiration is the water vapor or clouds we see emanating from a well forested hill or mountainous area during the day.

5. Helps Reduce Temperature

As a result of evapotranspiration which was previously explained, plants can reduce the overall temperature in a room.

Dr. Leonard Perry, a professor at the University of Vermont adds that “a USDA estimate is that proper use of plants could decrease air temperature in an office by as much as 10 degrees.

A direct effect of an increased humidity is a reduction in room temperature and inturn, dehydration. 

Therefore, the air we breathe in a room with good humidity will not significantly take away moisture from our system which would leave us less dehydrated.

Having plants in some spaces has been proven to reduce the overall temperature inside buildings and apartments. This directly reduces energy costs when it comes to climate control.

For this reason we are seeing more greenery on the rooftops of buildings and even some homes as the plants tend to “soak up” the sun’s hot rays to produce lush vegetative growth.

Houseplants

Most Common and Best Plants to Purify Air 

From research it was noted that the efficiency of which plants remove VOCs from the air varied with the plant species. 

Here is a list of the most common species of plants which stood out in the experiments.

  1. Golden Pothos 
    Golden pothos
    Golden pothos or devil’s ivy, is native to the Solomon Islands and is a climbing vine that produces abundant yellow-marbled foliage and can reach up to 40′ or more in length.

    The golden pothos was found to be good at removing formaldehyde along with other plants. Source. [Google Scholar]
  1. Spider Plant
    spider plant
    The spider plant is a cultivar of a south african plant having long narrow green leaves usually striped with white or ivory and producing white flowers on long hanging stems.

    The spider plant was shown to have the greatest effect in the removal of formaldehyde in an experiment comparison with aloe vera and golden pothos, which also removed their fair share of formaldehyde. Source. [Google Scholar]
  1. Snake plant (Mother-in-Law’s Tongue)
    Snake plant
    Sansevieria are evergreen perennials that can grow very tall. They have sword-like leaves which can grow to approximately 2 feet in length.

    The foliage is stiff, broad, and upright, in a dark green color variegated with white and yellow striping.

    On the list of plants that remove VOCs, the snake plant came in 9th and does much work in removing Toluene and a-Pinene.
  1. Dragon tree
    dragon plant
    The dragon tree leaves are deep green with narrow reddish edges. Lower leaves fall off with age leaving distinctive diamond-shaped leaf scars on the stems.

    This plant did pretty well in removing formaldehyde, benzene and Trichloroethylene in the NASA test.
  1. Philodendron
    Philodendron
    Philodendrons are known for how easy it is to grow and care for as the plant can adapt to any environment. The large leaves, which can be oval, pointed or heart-shaped, but can also have deep incisions.

    This plant has been found to remove formaldehyde better than other plants.
  1. Peace lily
    Peace lily
    Peace lilies are sturdy plants with glossy, dark green oval leaves that narrow to a point. The leaves can also rise directly from the soil.

    This plant will also periodically produce lightly fragrant white flowers that resemble calla lilies

    The peace lily was also found to be good at removing benzene, formaldehyde and Trichloroethylene.
  1. Spanish Moss
    Spanish Moss
    From a report from Joao Paulo Machado Torres in this article, Spanish moss (Tillandsia usneoides) is used as a sentinel species to detect and absorb mercury from the air in shops contaminated by the gold trade in the Amazon

Plants and the VOCs they Remove

Plant SpeciesBenzeneFormaldehydeTrichloro-
ethylene
Golden Pothoscorrect
Snake Plantcorrectcorrectcorrect
Spider Plantcorrect
Dragon treecorrectcorrectcorrect
Philodendroncorrect
Peace lilycorrectcorrectcorrect
Wax Plantcorrect

How Soil in Potted Plants Helps in purifying air 

It has been shown from the above experiment that potting soil mixed with substrates such as activated carbon also aided in the reduction of VOCs from the air.

This is primarily because roots also absorb oxygen and other air particles along with it. 

This air draw would introduce the contaminants into the soil with the activated carbon where it would be filtered out.

It was also noted that potted soil with a larger exposed surface area did even more work in reducing volatile compounds or VOCs from the air. 

Wet Potted plant soil

The Truth about Plant’s air puring abilities through Research

Although the NASA experiment stated above said that plants can significantly reduce the amounts of VOCs in the air.

This experiment was done in a very enclosed environment which proves that plants have the ability to remove toxic chemicals.

When you really think of it, if you were to be placed in a closed room with oxygen and a large concentration of VOCs.

The VOC levels will also decrease because we would also breathe in a mixture of these gases which would end up in our system as well.

However, the experiment did not take into consideration the quantity of plants and the length of time it would take to actually remove known VOCs in an average sized room.

In extrapolating the information from the experiments, it was noted that for a single 10ft X10ft room it would take an entire nursery of plants to actually start reducing the VOC’s.

However this debunking theory is entirely based on the removal of VOCs in a room. 

On the other hand we have carbon dioxide which is produced by us when we breathe, which we know plants can definitely remove through photosynthesis.

How Much Plants are Needed to Clean the Air?

Now, from the above study we know that plants can definitely clean the air of VOCs. 

It was done in an enclosed environment with all other conditions being kept constant and the theory was proven. 

One main question arises which is still unanswered. 

How much plants does It really take to clean the air?

The truth is, no one really has the answer, unless some other study is done to give us a really scientific and definitive answer. 

What we do know however, is that plants readily consume carbon dioxide and can significantly reduce CO2 levels within a closed environment while increasing the oxygen levels at the same time. 

Therefore, having plants within our living spaces can definitely have an impact on our health and well-being. 

How much plants you may want to have within your space is definitely up to you and with the above guide you will have a good idea on which plant or plants can be of most benefit to you depending on your liking. 

Having plants in the home has its rewards and ensuring that they are sited in a place that is safe to both you and your pets can add that extra peace of mind to ensure that you get the most out of you plants.

If you would like to know the places to safely put plants in the home, you can see our in-depth article on this topic here.

The Importance of Air flow in the Home

Air flow in the home is important in removing any build up VOCs. Modern HVAC systems incorporate scrubbers which circulate the air, passing it through deep bed scrubbers filled with activated carbon. 

The activated carbon absorbs pollutants in the air which is then reintroduced into various parts of homes or buildings. 

In other instances air circulation occurs where there is conventional air flow through the home form air blowing through one window and leaving through another. 

This leaves no room for CO2 or any other released VOCs to accumulate in the home. 

In such cases, the purpose of having plants in the home is purely recreational which has other benefits linked to calming the senses and creating a sense of serenity. 

However, with good airflow, in some cases crates another issue. Dust! Which leads us to the next question. 

spider plant

Can Plants Remove Dust from the Air?

Dust can come from the air moving through our home from the outside and is more pronounced when there is some type of construction activity outside or if we live in dry arid regions. 

Dust can also be produced in enclosed spaces from fabrics and even the dead skin that we shed on a daily basis.

But can plants really remove dust? 

It has been shown that some plants can remove dust particles from the air better than others. This is because these plants simply have a larger surface area and act somewhat like a duster.

In a closer comparison, you may have noticed that a duster has thousands of small bristles. These bristles increase the surface area of the duster. Continuous movement of the bristles creates static. 

It is the static force that causes positively charged dust particles to be attracted to and stick to the duster.

Plants work in the same way, Let’s take a spider plant for example the spider plant would be good at removing dust since it has multiple blades of leaves growing outwards and with its movement can trap a lot of dust.

Another good example is the foxtail fern, this plant fits the description of the average duster and works well in scrubbing dust from the air.

A general rule of thumb is that if the plant has a large surface area then it will be goo at removing dust from the air.

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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