The humble doorknob—an object we grasp dozens of times a day without a second thought—stands in stark contrast to the toilet seat, which we instinctively associate with germs and filth. Yet, a ranking of the truly dirtiest items in a home holds a surprising revelation.
According to various studies on the subject, doorknobs can harbor up to 8,500 bacteria per square centimeter—a figure significantly higher than what is typically found on toilet seats. This finding challenges common perceptions, as toilets retain their reputation as the most contaminated area of ​​the home, while doorknobs are almost invariably overlooked during routine cleaning.
However, the most striking statistic relates less to the bacterial load itself than to the potential for transmission. One study demonstrated that a virus deposited on a single building entrance doorknob could spread to 40–60% of surfaces within that building—and to its occupants—in just a few hours. It creates a genuine, invisible domino effect, where a single contact point rapidly becomes a transmission hub for the entire household. The mechanism is deceptively simple: a contaminated hand touches the knob, the next person touches it and then rubs their eyes or nose, and the cycle repeats silently with every new contact.

What this task entails in practice

Cleaning doorknobs and light switches involves wiping these high-touch surfaces with a cloth dampened with a suitable cleaning product, paying special attention to the most frequently used areas of the home (entryway, kitchen, bathroom). Allow about five minutes for this task; a weekly routine is recommended under normal circumstances, while daily cleaning is advised if someone in the household is ill.

Tips and tricks to limit the spread

70% household alcohol remains the most effective solution against viruses and bacteria: highly potent in hospital settings, it dries quickly without requiring rinsing, making it a particularly convenient option for a quick clean of frequently touched surfaces.
If a household member falls ill, increasing the cleaning frequency of shared door handles to at least once a day effectively breaks the chain of transmission identified by researchers; it is precisely this recurring link—a handle touched by a contaminated hand followed by a clean one—that drives the rapid spread observed in the study.
Don't forget light switches; they are often touched immediately after a door handle in a single motion (turning on the light when entering a room), making them a similarly strategic contact point that should be cleaned systematically alongside the handles themselves.

With contamination capable of spreading to 60% of a building's surfaces within just a few hours from a single contaminated handle, this often-overlooked cleaning step deserves a real place in your weekly routine. Simply wiping down these unnoticed contact points regularly can effectively break the chain of transmission before it spreads throughout the entire household.