Is it safe to run an essential oil diffuser at work in a closed office?

What's actually in it

Essential oil diffusers work by aerosolizing tiny droplets of oil into the air. The oils are concentrated plant chemistry, and once airborne, they're VOCs: volatile organic compounds. They also form ultrafine particles by condensing on indoor dust. Tea tree oil, eucalyptus, citrus, and cinnamon are among the strongest emitters. Other coworkers with asthma, migraines, pregnancy, or chemical sensitivity don't get to opt out of the cloud in an open office.

Indoor air in a sealed office already concentrates every other pollutant. Adding a diffuser makes that worse, not better.

What the research says

A 2025 study in J Occup Environ Hyg measured VOC and particle emissions from tea tree oil in essential oil diffusers. A single diffuser raised VOC levels in an office-sized room into a range where respiratory irritation is well-documented. Multiple diffusers ran together compounded the effect. Coworkers with asthma were the first to complain in any real-world setting.

For personal use in a private home, diffusers are a judgment call (skip them around babies, pets, and asthmatics). In a shared office, essential oils are a "no" unless the team has explicitly agreed to it. A personal inhaler (small glass tube with a cotton wick) lets a person enjoy a scent without forcing it on others. If air freshening is the goal, a HEPA purifier running in the corner actually removes odors by filtering them instead of covering them.