Because door handles are commonplace and are interacted with by large numbers of people on a daily basis, they present opportunities for growth of bacterial colonies.
Many factors determine the habitability of a door handle for a population of bacteria. The material of the handle itself contributes to the growth of bacteria, with most door handles being constructed of stainless steel – a suitable home for bacteria. The material can affect the time bacteria can survive on door handles, but more important is the temperature and humidity of the environment. A hospitable environment can allow bacteria to thrive for anywhere from a few hours to a few weeks on a surface.
A crucial factor in the bacterial growth and spread is the location of the handle. A low-touch handle, such as that of a rarely opened closet will have significantly fewer bacteria than the high-touch handles in a busy public bathroom due to the frequency of contact with people's hands. Door handles in locations where elderly people or immune compromised people frequent should be cleaned frequently.
Precautions and preventions
The most obvious way to prevent the contraction and spread of direct contact diseases is to try not to touch door handles at all, of course this is not always possible. A door may be held open with a device such as a door holder or door closer, which can automatically release the door upon the sound of a fire alarm and protect a building in the event of a fire.
An ultraviolet door handle attendant can be installed to sterilize the existing handle. Automatic door handle sanitisers are used mainly in hospitals. These units spray a tiny amount of sanitiser onto the door handle after each use.
Automatic doors are also becoming more and more popular in hospitals, chemists and other public buildings due to them reducing the risk of cross-contamination since there is no need to handle the door at all. Another prevention technique, which is mainly used in luxury hotels, is the use of a doorman who will open and close the main door, screening visitors and deliveries. These mean passers through do not have to touch the door at all therefore eliminating all risk of catching or passing on direct contact diseases. Precautionary measures which can be taken in order to prevent such diseases include wearing gloves, using paper towel or tissues to open handles or using tools, like the loodini, to avoid using door handles all together.
The primary risk with touching a door handle is the subsequent transfer of bacteria into the body through the mouth, nose or eyes by touching the face. With this in mind handles have been developed that can be operated using the forearm or the foot.
Types of bacteria
Door handles provide a suitable environment for bacteria to spread easily, this makes it a hotspot for bacteria to gather and create colonies. After a study conducted by the Worcester Polytechnic institute, WPI, gathered that 1323 bacterial colonies were displaced among 27 door handles. This study was conducted on the university campus, an area which is considered fairly dense in population, which many people will access these doors, providing a host for the bacteria to travel elsewhere. Flu viruses can have the potential to last up to 24 hours on door handles. Over this period of time, this gives measure for the bacteria to further spread or even other door handles. This bacteria on exposure can be harmful to humans, potentially infecting us with diseases such as e-coli, fungal or other viral infections. Many people may forget the potential for bacteria to thrive on door handles, and after exposure may touch their face, or other places that may lead to ingesting it into their body. The study conducted by WPI using a hidden camera discovered that out of 1,060 people over a period of 35 minutes, 86 people touched their face after exposure with the door handle.