A Study of Interior Landscape Plants for Indoor Air Pollution Abatement
Wolverton, B. C. et al. · 1989 · NASA — John C. Stennis Space Center
- Tier
- Historical
- Audience
- For all readers
If you have ever seen a graphic headlined “10 plants that purify your air,” you have seen the long shadow of this report. In 1989, B. C. Wolverton and colleagues at NASA’s Stennis Space Center published A Study of Interior Landscape Plants for Indoor Air Pollution Abatement — a short technical paper that has since been cited, screenshotted and distorted more than almost any other document in houseplant culture. We’re reviewing it not to debunk plants, which we love, but because owning what a primary source actually says is exactly the kind of thing the Library is for.
What it set out to do
NASA’s interest was not your flat. It was sealed, recirculating environments — spacecraft and closed life-support systems — where air can’t simply be exchanged with the outside. In that context the question “can living plants scrub volatile organic compounds from a closed atmosphere?” is both sensible and important. The team sealed individual potted plants inside small Plexiglas chambers, introduced a known quantity of a single VOC — benzene, formaldehyde or trichloroethylene — and measured how much disappeared over a day.
What it actually found
Two things, both real. First: yes, inside those chambers, common foliage plants removed measurable amounts of all three chemicals. Second, and more interesting: a large share of the removal was attributable to the root zone and its soil microorganisms, not the leaves alone — which is why Wolverton’s later work leaned toward plant-and-activated-carbon biofilters rather than pots on a shelf. That second finding is the genuinely useful part of the paper, and it’s almost always the part that gets lost.
Why it’s constantly misread
The misreading is a unit error dressed as a wellness claim. A sealed one-cubic-metre chamber with one plant and one injected pollutant is not a living room. A real room has ventilation — typically half to one full air change every hour — which dilutes and removes pollutants far faster than a plant can absorb them. Reporting per-plant uptake in a closed box and then implying “so N plants will clean your home” silently assumes your home is a sealed box. It isn’t, and that single unstated assumption is where the popular story falls apart.
What modern work says
The decisive reassessment is Cummings & Waring’s 2019 review in the Journal of Exposure Science & Environmental Epidemiology, which pooled decades of chamber studies (including the NASA data) and converted them into a clean-air delivery rate — the metric used to rate actual air purifiers. The verdict was blunt: to match the air-cleaning a normal building’s ventilation already provides, you’d need somewhere between roughly ten and a thousand plants per square metre of floor. A few pots on the windowsill make no measurable difference to the air you breathe. Open a window instead.
How we’ll use it
This is our reference whenever we need to gently correct the “air-purifying plant” claim without sneering at it — which, given Mist’s wellness audience and Myrtle’s evidence-first voice, is a line we’ll walk often. The honest position is: keep plants for the documented benefits (they’re calming, they’re beautiful, caring for them is good for you) and not for an air-purification effect the data doesn’t support. The paper itself is freely available through NASA’s technical reports server, and we’ll link readers to the primary source rather than to a listicle about it.
Who should read it
Anyone who has repeated the air-purifying claim — which is most of us — should read at least the abstract and the chamber methods. Plant writers and wellness brands especially: it’s a short, clarifying lesson in how a careful narrow result becomes a sweeping wrong one. General readers can skip the body and take the summary: real science, real finding, wrong application.
The bottom line
A competent, honest piece of feasibility research that was never about your living room and never claimed to be. The fault lies entirely with what came after it. Read it as history — and as a small masterclass in how to misuse a primary source — then go and enjoy your plants for the right reasons.
Reviewed 2026-05-28. NASA technical report (1989), Stennis Space Center. Primary source available via the NASA Technical Reports Server (NTRS). Modern reassessment: Cummings & Waring, J. Expo. Sci. Environ. Epidemiol. (2019).
- · Genuinely controlled for its purpose: sealed-chamber measurement of three named pollutants (benzene, formaldehyde, trichloroethylene) across common foliage species — a clean feasibility study, not hand-waving.
- · Identified that the root zone and soil microorganisms — not just the leaves — do much of the VOC removal. A real finding, and the part most often dropped from the popular retelling.
- · Honest about its own context: this was research for sealed spacecraft and closed life-support systems, where a glorified terrarium is exactly the right model. The sealed chamber wasn't a flaw; it was the point.
- · Catalysed three decades of legitimate phytoremediation research that continues today.
- · The sealed chamber is the whole problem the moment the result is exported to your living room: no ventilation, a tiny air volume, an enormous plant-to-air ratio, and a single pollutant injected at high concentration.
- · Per-plant removal measured in a closed box cannot be scaled linearly to a leaky, ventilated, multi-pollutant real room — but that is exactly the leap a thousand listicles made.
- · Cummings & Waring's 2019 review recomputed the results as a clean-air delivery rate and found you'd need on the order of 10–1,000 plants per square metre to rival simply cracking a window.
- · Not the paper's fault, but its legacy: decades of marketing have laundered a narrow feasibility study into a wellness truism. It needs reading with that history in mind.