In this study it was concluded that certain species of plants such as ivy ( Hedera helix ), pothos ( Scindapsus aures or Epipremnum pinnatum ), the popular ribbons ( Chlorophytum elatum ), ficus benjamina ( Ficus benjamina ) or espatifilos ( Spathiphyllum ) among others , were capable of eliminating toxins (benzene, toluene, formaldehyde, trichlorethylene) in addition to absorbing CO2 and releasing oxygen.
However, a new systematic review of the scientific literature published in JOurnal of Exposure Science & Environmental Epidemiology shows that this ability may have been greatly overestimated (although this ability remains true).
In this study, they found that natural ventilation indoors is a much more effective and faster way to remove potentially harmful air pollutants. In addition, it is also key to reduce indoor emissions and to ventilate when doing activities such as cooking or cleaning, and to use particle filters.
Why was NASA wrong about indoor plants?
NASA’s mistake when estimating the rate of air clearance lies in how the study was conducted. They were made in sealed chambers in laboratories that did not accurately mimic the factors that influence indoor environments.
The team that did the systematic review reviewed a dozen studies that took the VOC removal data and transformed it into a comparable metric. They called this metric CADR (Clean Air Release Rate), and it was used to parameterize indoor cleaning.
Using this metric, the impact of plants to remove volatile organic compounds was compared to the ability to remove them from other mechanical and natural ventilation systems. Ventilation systems were much more efficient than plants.
In a small office, it would take between 10 and 1000 plants to have the same impact as ventilation at a rate of 1 air change per hour, which is otherwise a typical value.
Indoor air pollutants
Indoor air pollutants can be divided into three main categories:
Volatile organic compounds
These are gaseous phase molecules that are emitted from many sources such as consumer products, cleaners, and building materials. They tend to reside in the air so they are easier to remove.
Semi-volatile organic compounds
This category includes products such as pesticides, flame retardants, and plasticizers. They tend to be sticky and stick to indoor surfaces and can persist for months or years.
Particulate matter can be solid or liquid and can be found floating in the air. These pollutants are linked to asthma, allergic reactions, irritation, and other respiratory problems.
The bottom line is that the best way to have a healthy home is to reduce indoor air emissions, ventilate very well especially during cleaning or cooking, and use particulate matter filters.
Although indoor plants are not as effective for this purpose, it all adds up and their beauty is in itself a reason to have them at home.