Disinfection can be defined as the ‘action of killing or destruction of infectious agents outside the body by the help of disinfectants like direct exposure to chemical or physical agents’. It can also refer to the action of antiseptics as well as disinfectants. A disinfectant is a substance that destroys harmful microbes in order to prevent transmission of disease. It can be found in solid, liquid, gas or power form. It is also called a germicide or sterilizer. There are some chemical agents who only restrain the growth of disease germs, but do not destroy them are called ‘antiseptics’ like, borax, boric acid, lime etc. There are others that conceal the smell or neutralized bad odors known as ‘deodorant like camphor, phenyl etc.
Disinfectants can be classified into three major categories, such as:
1. Natural Disinfectants:
Fresh air and sun-light are the two important natural disinfectants that destroy many disease producing germs.
Direct and continuous exposure to sunlight kills many disease producing germs, specially the action of ultraviolet rays. Hence, articles such as linen, bedding and furniture can be disinfected by exposure to direct sunlight for several hours. In a country like India, where so much of sunshine is available it can be considered as one of the cheapest and readily available disinfectants.
(b) Fresh air:
Exposure to open air (airing) is a powerful, though slow disinfectant. It acts mainly on account of the presence of oxygen in it. Through the act of drying or the evaporation of moisture, the growth of most bacteria can be prevented.
However, natural agents like sunlight and air can not be totally depended upon for disinfection.
2. Physical Disinfectants:
The common physical disinfectants are:
For cheap articles, destruction by fire is the best method for killing germs. All articles like contaminated dressing, rags and swabs can be disposed off by burning, as in dry up; the germs will be floating in the air. Faces can be disposed off by burning. It should be done in an incinerator, not in open air.
(b) Hot air:
It is very useful for sterilizing articles such as glassware, syringes, swabs, dressings, French chalk, oils, valentine and sharp instruments. Hot air sterilization is usually done in a hot air oven, having 160-180 degrees centigrade for at least one hour.
Boiling is an effective method of disinfection for small instruments, tools which are used for operations. Boiling for 5-10 minutes only kills bacteria not the viruses. More than 30 minutes of boiling is ideal to disinfect linen, utensils and bedpans etc. It is a slow process and quiet unsuitable for thick beddings and woolen materials.
It is very useful to sterilize the surgical instruments and other accessories like bandages, dressings, surgical instruments etc. through ionizing radiation. This method is the most effective and ideal but very costly. However, commercially this method is widely accepted as it is very safe to use.
3. Chemical Disinfectants:
Chemical disinfectants are useful in case where natural or physical disinfectants can not be based. It may be found in either solid, liquid or in gaseous form. The substances most commonly used as chemical disinfectants are carbolic acid or phenyl, iodine, chlorinated lime or bleaching power, formalin and lime alone, which are cheapest of all disinfectants.
In case of disinfection of rooms, surgical operation theatre, toilets, hospital wards, large amount of clothing’s and linens, ponds, wells, drinking water etc. This type of chemical disinfectants can be used according to each one’s effectiveness and suitability.