The question sounds simple. The answer, once you examine the actual measurement science behind it, is more interesting than either “yes” or “no”.

The houseplant-as-air-purifier idea can be traced to a 1989 US study, conducted for Nasa as part of research into closed-loop life support systems for space stations. In sealed, controlled chambers, certain plant species reduced concentrations of volatile organic compounds (VOCs). These are chemicals that easily evaporate into the air at room temperature, including some toxic ones like benzene, trichloroethylene and formaldehyde. The science was sound. The problem is the leap from a sealed Nasa chamber to a living room. This distinction matters enormously, and it underpins almost every piece of inflated coverage about houseplants’ purifying abilities that has followed.

Most studies showing that houseplants remove pollutants share a fundamental design feature: small, sealed chambers with artificially high concentrations of pollutants introduced as a single high dose. A plant is placed inside the chamber, concentrations of pollutants are measured over time and a removal rate is calculated. This design works well for comparing plants to each other. It works poorly for predicting what happens in your home.

The critical missing variable is what building scientists call the air exchange rate. This is how quickly outdoor air naturally replaces indoor air through gaps, walls and ventilation........

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