Choosing Between Real and Artificial Christmas Trees: What Recent Research Reveals
Each year, the familiar holiday debate returns: should homes decorate with a natural Christmas tree or an artificial one? Both options offer clear benefits. Real trees can be more environmentally friendly in many cases, since their production often involves lower CO2 emissions than some artificial trees. From a health perspective, live trees can change indoor air chemistry and may affect people who are sensitive to volatile organic compounds, or VOCs.
A recent study looked at how natural Christmas trees influence home air quality and the well-being of residents. While many families love the fresh scent of a live tree, that aroma comes from VOCs in the surrounding air. Until now, the exact emission levels and health effects of different tree varieties were not fully understood.
According to Dustin Poppendieck, an environmental engineer at a standards laboratory, the tree’s fragrance acts as a chemical signal for the air we breathe. He notes that researchers aimed to identify which chemicals are released, in what amounts, and how they add to the overall chemical load inside homes.
Planting a fir tree for Christmas. Pixabay
To answer these questions, the team sealed a spruce tree in a controlled chamber and tracked the VOCs emitted over 17 days. They also explored whether these VOCs could react with other indoor air components to form new compounds.
Cough and throat irritation
The researchers’ findings, reported in Indoor Environments, show that the familiar Christmas tree scent comes from a group of VOCs known as monoterpenes. These compounds are also common in scented products, air fresheners, candles, and some personal care items.
Outside, conifers—the family that includes most Christmas trees—release monoterpenes and can influence outdoor air quality. Inside homes, the release levels when a tree is cut and placed indoors were less clearly understood.
Earlier studies indicate that monoterpenes can react with ozone, a pollutant formed when sunlight interacts with pollutants. This reaction can produce symptoms such as coughing and throat irritation. Ozone can also react with other indoor chemicals to form new compounds. The team sought to observe these dynamics in a simulated home environment with an indoor tree.
One of the researchers beside the experimental tree. M. King/NIST
In an environmentally controlled chamber, the tree’s emissions were measured in real time using PTR-MS, a technique that detects trace organic compounds in the air. The simulated home atmosphere included a typical Christmas lighting setup with a day–night cycle, and the tree was watered daily while outdoor air was introduced at a rate typical for homes. Continuous air monitoring captured the evolving chemical profile inside the chamber.
Reactive chemicals
Monoterpenes emerged as the most abundant VOCs, with 52 distinct compounds identified. Concentrations peaked on day one, then declined sharply by day three. Initial levels were similar to those seen with a plug‑in air freshener or a newly built house, but over time they dropped to roughly one‑tenth of the original amount, according to the researchers.
The scientists then introduced ozone into the chamber to study its impact on indoor air chemistry. They found that ozone reacts with monoterpenes to form byproducts such as formaldehyde and other VOCs and reactive chemicals.
With ozone present, monoterpene levels declined further while formaldehyde levels rose, altering indoor air chemistry. However, the formaldehyde concentration remained very low, around one part per billion, far below typical indoor levels in many homes.
For individuals sensitive to VOCs, a live Christmas tree could cause watery eyes or a runny nose during the first days of indoor use. Practical steps include opening a window near the tree to dilute VOC exposure. If possible, storing the tree outdoors or keeping a freshly cut tree in a garage for a few days can reduce emission intensity before bringing it inside.
Overall, the researchers note that for most people, placing a freshly cut natural tree indoors should not pose a major health concern, and many still choose live trees for their aroma and tradition.
New method: trees for rent
When weighing environmental impact, a greener impression may come from an artificial tree, but plastics such as PVC used in many fake trees can generate greenhouse gases during production and are not biodegradable. Independent estimates suggest that a two‑meter artificial tree can emit about 40 kilograms of CO2, while a natural tree of similar size emits roughly 3.5 kilograms. To exceed the environmental advantage of natural trees, an artificial tree would need to be reused about a dozen times.
Supporters of artificial trees highlight cost savings through reuse, the absence of fungi or mold concerns, and a pine-like aroma. In contrast, backers of live trees emphasize local sourcing, supporting local economies, and sustainability, noting that a large share of artificial trees are manufactured abroad, with a notable portion coming from overseas.
In the United Kingdom, some outfits are piloting tree rental programs. These trees are grown in pots that allow them to be dug up and replanted each year. Customers pay a deposit and receive guidance on keeping the tree healthy, such as avoiding heat sources and ensuring regular watering.
Environmental considerations continue to shape the conversation about festive choices. A balanced approach blends tradition with mindfulness, encouraging families to weigh fragrance, sustainability, and indoor air quality when celebrating the season.