In 1989, NASA published a study that would reshape how designers and health-conscious homeowners think about indoor plants. The research — conducted by Dr. Bill Wolverton for the NASA Clean Air Study — tested which common houseplants were most effective at removing volatile organic compounds from enclosed air. The study was designed for space station air purification, where sealed environments made air quality a survival issue. What it revealed applies to every home on Earth: specific plant species metabolize formaldehyde, benzene, trichloroethylene, xylene, and ammonia as part of their normal biological function. These are the same compounds released by building materials, furniture, cleaning products, and personal care items in virtually every modern home.
The Most Effective Species
Peace lily (Spathiphyllum) — the top performer in NASA’s study for formaldehyde, benzene, and trichloroethylene removal. Thrives in low to moderate indirect light and blooms indoors. Prefers consistently moist soil but tolerates occasional neglect. English ivy (Hedera helix) — exceptional at formaldehyde removal, effective in hanging baskets where its trailing growth pattern maximizes leaf surface area. Boston fern (Nephrolepis exaltata) — formaldehyde removal plus natural humidification through transpiration, releasing moisture into dry indoor air.
Rubber plant (Ficus elastica) — a powerhouse formaldehyde remover with thick, glossy leaves that tolerate low light and extended periods without water. One of the most forgiving houseplants available. Snake plant (Sansevieria trifasciata) — uniquely converts CO2 to oxygen at night through CAM photosynthesis, making it ideal for bedrooms. Nearly impossible to kill. Pothos (Epipremnum aureum) — thrives in virtually any indoor condition including low light, dry air, and irregular watering. Effective formaldehyde absorber and one of the easiest plants for beginners.
How Many Plants and Where to Place Them
NASA recommended approximately one plant per 100 square feet of floor area for meaningful air quality improvement — roughly 15–20 plants for a typical home. That sounds like a lot, but distributing 2–3 plants per room covers most of the house. Even a single plant in a room contributes measurable benefit, and the effect is additive — more plants, more filtration, more impact.
Beyond air quality, research has documented that indoor plants reduce cortisol levels, lower blood pressure, improve mood and concentration, accelerate recovery from illness, and reduce perceived stress. A 2015 study in the Journal of Physiological Anthropology found that interacting with indoor plants reduced both physiological and psychological stress compared to computer-based tasks. Plants are functioning biological systems that interact with the human body on multiple levels simultaneously — they are not decoration.
Placement Strategy
Bedroom: Snake plant (produces oxygen at night). Bathroom: Pothos or peace lily (thrive in humidity and low light). Kitchen: Herbs on a windowsill — basil, rosemary, mint — provide greenery and fresh cooking ingredients. Living room: A fiddle leaf fig or rubber plant anchors the room with scale. Home office: Plants on or near the desk reduce stress and improve focus during sustained cognitive work.
Where To Start
- Start with pothos and snake plant. Nearly indestructible, effective purifiers.
- Add peace lily or Boston fern to rooms with light. Excellent formaldehyde removal.
- Aim for 2–3 per room. The effect is additive. More plants, more benefit.
One of the most important things in design is bringing nature indoors. Plants are the simplest, most beautiful, and most biologically effective way to do it — and they improve the air quality of every room they occupy while improving the health of every person who lives with them.
How many living plants are in your home — and how does the room with greenery feel compared to the one without?