The hygiene hypothesis, a relatively new theory, states that people in the developed world don’t challenge their immune systems enough. As a result, the body’s natural defenses overreact to small irritants such as pollen or dust. This is especially true for children. If a child’s immune system is not challenged early in life, the system may not develop properly, which has been linked to an increased risk of developing asthma and allergies later in life.

Currently, there are several reasons for the lack of exposure to germs. People have smaller families, which reduces the amount of germs brought into the house. Fewer people live on farms, which indicates that many have no contact with animals and their germs. Also, we spend much more time indoors and are not exposed as often to soil. Finally, many people over-use anti-bacterial products, not only eliminating the bad bacteria, but also the good.

Finding the right balance

Basic hygiene, such as handwashing with soap and water regularly, coughing and sneezing into our arms, are two very simple and effective ways of reducing the spread of germs. Taking food safety precautions, (e.g., proper purchasing, transport, storage, preparation and serving) as well as cleaning and disinfecting surfaces, are easy ways to help you stay healthy in your home and workplace.

A Global Perspective

It’s better to risk cleaning too much rather than too little. The World Health Organization estimates that every year two million people, most less than 5 years old, in developing countries die due to diarrhoeal diseases. This death rate can be cut in half by handwashing with soap and water. (World Health Organization. Water supply, Sanitation and hygiene development. http://www.who.int/water_sanitation_health/hygiene/en/)

Key References
Bloomfield, S.F., Stanwell-Smith, R., Crevel, R.W., & Pickup, J. (2006). Too clean, or not too clean: the Hygiene Hypothesis and home hygiene. Clinical & Experimental Allergy 36(4), 402-425.

Curtis, V. & Cairncross, S. (2003). Effect of washing hands with soap on diarrhea risk in the community: a systematic review. The Lancet Infectious Diseases, 3, 275-281.