The German practice of “lüften” is gaining traction on social media. It may improve your home air quality. “Lüften” roughly translates to “ventilate” or “airing out” and involves just that — opening windows in your home once or twice a day, regardless of the outside temperature, to eliminate stale air. The term has recently gone viral, trending on Google and featuring in tens of thousands of posts across TikTok, Instagram, and Meta. Some are simple, featuring pleasant music playing while the video host moves through their house, opening windows.

The practice of lüften is long established in Germany, where many landlords make tenants agree to air out their apartments for several minutes daily, if not multiple times per day, since mold removal often falls on the landlord.

Experts say lüften actually works. The  Environmental Protection Agency recommends opening windows to reduce the concentration of volatile organic compounds in the home, which are released by a vast array of household items, including furniture, mattresses, cosmetics, and cleaning products. These compounds can cause adverse reactions like headaches, itchy eyes, and breathing problems. According to Dr. Parham Azimi, research associate at the Harvard T.H. Chan School of Public Health, there’s also reason to believe airing out a home regularly could help control household mold. In his research, keeping windows closed correlated with a higher likelihood of mold.

But outside air is not always clean, due to toxins that it may contain. Tiny particles from traffic, factories, and gases such as nitrogen dioxide can cause us damage. Where you live shapes the trade-off. Homes close to busy main roads or near recently burned areas tend to have higher levels of traffic- and debris- related particles.