An Internet search for Web sites containing “houseplant air pollution” yields more than seven hundred entries. Most of them offer to sell me plants that clean indoor air. They vaguely refer back to a series of experiments conducted by Dr. Bill Wolverton at the National Aeronautics and Space Administration in 1984. Dr. Wolverton discovered that certain houseplants, growing in closed chambers, removed air-born contaminants like benzene and formaldehyde.
In the years since, millions of houseplants have been sold to homeowners hoping to protect their families from pollution. Have the houseplants behaved as expected? Not likely.
Wolvertons’ research, you see, dealt with plants in a closed container. While there is no doubt that pollutants in the chamber were removed, it is estimated that you’d need six hundred and eighty plants in the average home to achieve the same results.
Further, the most promising avenue of pollution removal was not via the plant leaves but by their roots. When contaminated air contacted the soil, roots absorbed the chemicals. This indicates that the best way to have houseplants clean your surroundings is to blow household air through the soil and root system.
Six hundred plants in your home? Pumping air through your potting soil? Neither seem very appealing. Yet houseplants will continue to be sold as indoor air cleaners, even though the science behind the practice is minimal.
Houseplants are great to have…but don’t burden them with unrealistic expectations.