As the fear of the risk of catching a serious disease such as the coronavirus, H1N1 and deadly strains of the flu increases, more Americans are becoming concerned with keeping their homes germ-free. While it's not possible to eliminate germs and microbes entirely, learning about how long they live on different surfaces can help improve your cleaning regimen.
Lifespan of Cold and Flu Germs on Common Surfaces
When you're in the vicinity of someone suffering from an infectious disease like the flu, it's very easy for these germs to leave their body due to coughing, sneezing and bodily contact. Once these germs come into contact with surfaces commonly found in the home, they can remain infectious for quite some time out of the body. It's actually not correct to describe germs as "living" on surfaces as they are not alive in the sense that people are, and they require a living host to latch onto and replicate. The ability of a germ to make you ill degrades over time and if it is no longer "intact" it cannot cause an infection.
How Long Do Germs Live Outside the Body?
There have been several studies looking at how long germs remain intact on surfaces with some differences in the results. For example, these studies found a wide variety of time frames for germ viability on hard surfaces:
- A study of influenza germs on stainless steel and plastic found they could remain viable up to 24 to 48 hours. This same study found that germs on tissues, fabric and paper remained viable for between eight and 12 hours.
- A study in England in 2011 looked at flu germs on household surfaces and found that germs were no longer viable after about nine hours at the longest. Surfaces they studied included computer keyboards, telephones, stainless steel, plexiglass and light switches. In comparison, germs on porous surfaces like fabric and wood only remained intact for about four hours.
- A longer time frame was found in a study in 2016 looking at stainless steel surfaces, which found that flu germs can remain viable up to seven days after the surface was contaminated.
- Unlike stainless steel, germs seem to have a much shorter viability time on substances made with copper, with the average time germs can be infectious lasting about six hours or less.
- A research study in a hotel found that 60% of volunteers picked up the cold virus after about an hour after surfaces such as telephones and light switches had been contaminated. However after 18 hours the rate of transmission dropped to only 33%.
- Another study found that dollar bills could carry intact germs for approximately three days.
Soft, Porous Surfaces Vs. Hard, Non-Porous Surfaces
While there is a range of times that cold and flu viruses can live outside the body on common surfaces, it's clear that there's a definite difference between soft and hard surfaces. Because germs need a moist environment to thrive, such as inside the human body, they tend to degrade faster on soft surfaces that pull moisture away from them. Germs are also weak to temperature changes, UV light, changes in alkalinity and acidity, humidity and the presence of salt. In general they will last longer in environments that are dark, humid, and warm.
Longer Viability Surfaces
Surfaces that are likely to have longer germ viability include:
- Equipment made from hard plastic and metal
- Household appliances like refrigerators and stoves
- Light switches
- Paper that is less porous such as money and printing paper
- Toys made from hard plastic and materials
Surfaces Where Germs Lose Viability Faster
On the other hand, you can expect germs to lose viability faster on softer surfaces such as
- "Hard" surfaces that are porous such as wood
- Paper products that are porous and designed for absorbing moisture such as tissues, toilet paper and paper towels
- Plush, stuffed toys
Enveloped Versus Non-Enveloped Viruses
Most cold and flu germs are from "enveloped viruses" which are inherently weak to being destroyed both by time, the environment and disinfecting agents. It's commonly thought that these viruses will no longer be viable after 48 hours at the longest. However, "non-enveloped" viruses can remain viable on surfaces for much longer. For example, the norovirus is notorious for making cruise ship passengers seriously ill and it can remain intact for several weeks. Another non-enveloped virus, calicivirus, can be viable for weeks on surfaces.
How Long Can Germs on Surfaces Cause Infections?
While cold and flu germs can be viable for days at a time on surfaces, this doesn't mean that they can make you ill all of that time. As the germs sit on the surfaces, they begin to degrade almost immediately. Cold viruses will lose their potency after about 24 hours and flu germs can degrade enough after only five minutes to no longer be able to make you ill. Knowing how long germs can cause problems can help you to realize when you should break out the disinfectant and cleaning supplies and clean right away. This is especially relevant if you have a sick person at home as the more you can clean up after them and avoid touching surfaces they have just used, the less likely it is you and others in the home will get sick.