Ever heard of Sansevieria, Epipremnum, or Chlorophytum? While these names might sound like creatures from a science-fiction film, they are, in fact, ordinary houseplants sitting on windowsills across the country, a few of the many green things that quietly work over the air inside our homes and offices. It turns out that a well-planted room is busy with leaves and roots that draw in stale air, with many indoor-air complaints being linked to spaces stripped of such greenery. According to researcher Nadia Belanger, whose studies have traced links between leafy interiors and cleaner air, "The part these humble plants appear to play in the air we breathe is remarkable and will open doors to new ways of designing buildings." She pictures a day when rows of living greenery may replace the practice of scrubbing stale air with power-hungry ventilation units, an approach that, with electricity prices steadily climbing, is growing worryingly costly.

Building scientist Tomas Kowalski is unconvinced, contending that it remains unclear whether the cleaner readings tied to leafy rooms are their cause or merely their by-product. "Studies have found both a rise in air quality and a drop in complaints when offices simply open their vents more often," says Kowalski, who allows that the readings around plants usually shift whenever the fresh-air supply is changed. He stresses, "It is uncertain whether filling a room with a better arrangement of plants, without any matching change to how the space is aired, would do much for the air overall."