Can green plants really sterilize germs, purify dust, or absorb formaldehyde?
Green Plants Can Purify the Air in Your Home? Not So True…
Green plants are popular. They complement just the right interior design and make us feel good. Of course, besides using them as decorations, many people actually purchase green plants for a particular reason: it is believed that indoor plants are able to purify the air.
【A NASA report misled us】
The idea that “greenery can purify the air” came from a scientific research conducted in the late 1980s.
Bill Wolverton is a NASA scientist who studied the ability of common houseplants to clean the air of a type of pollutants called volatile organic compounds (VOCs), such as benzene and formaldehyde, which are often released by common household products such as paint, nail polish, and shampoo. They can cause itchy throat in mild cases or nasopharyngeal cancer in severe cases. Unlike air pollutants such as soot or dust particles, VOCs cannot be filtered by air purifiers. Therefore they can accumulate in confined spaces, such as spaceships, laboratories, and homes.
Bill Wolverton’s research delivered a pleasing answer. The report says that plants are “a promising and economical solution …… If people are to enter enclosed environments, whether on Earth or in space, they must bring nature’s life support systems with them.” It is this study that provides the scientific basis for the online content on plants and air pollution.
There is nothing inherently wrong with Wolverton’s study, but to take the report’s results at face value would be to significantly overstate the role of plants. Wolverton measured whether houseplants could remove VOCs from a confined laboratory environment. However, a home is usually not a completely sealed space – it has open doors and windows; there is air circulation, and lots of clutter.
【Want to purify the air in a room with green plants? You have to place 1,000 of them in the room】
Over the years, studies have shown that indoor plants may be able to cleanse the air of certain pollutants. However, most scientists now believe this to be false.
For plants to really improve air quality, you have to plant them densely even in a tiny room to make it work.
Recently, Michael Waring, a professor of environmental engineering at Drexel University, along with his colleagues re-analyzed 196 studies on the ability of indoor plants to filter air. They found that certain species of plants removed more VOCs than others; however, once the condition of a “larger room” was introduced, none of the plants worked.
“Assuming there’s a room that is 10 feet long, 10 feet wide and 8 feet high; you would have to grow 1,000 plants in there to achieve the purification capacity of one air change per hour – the air exchange rate of a typical office ventilation system,” Waring said. That means an average of 10 plants per square foot. Even if you choose the most effective plants to filter VOCs, you still need more than one plant for each square feet in your room.
【Green plants are not completely useless as long as they make you happy】
In fact, happiness, not the removal of a tiny bit of air pollution, is the real reason to grow houseplants. These things around you that are full of life and that you care about will truly bring you happiness — whether they make the indoor air cleaner or not.