By Roger Gaudreault
PhD
Worldwide,
about two billion cases of food and water related infectious diseases are estimated
annually1. Public health as well as the economic impact of these
outbreaks are of major concern for both industrialized and emerging countries.
A few examples of outbreaks and their estimated cost since 1990: USA - E. coli
0157, $1.6 billion in 1991-99; Peru - cholera, $770 million in 1991; Asian
SARS - $39 billion in 2003; and, more recently, the H1N1 virus, where the economic
impact is unknown yet. Health authorities are taking precautionary measures
to prevent further spreading of these and other diseases. One of the basic
rules to minimize the propagation of microorganisms is hand hygiene.
There are two sides to hand hygiene: washing and drying. Most of us recognize
the importance of hand washing simply because throughout our lives we have
been told 'wash your hands'! However the drying side, which is also very critical
to reduce the propagation of pathogenic microorganisms, is generally neglected.
Why is hand washing so important? Because getting rid of these microorganisms
is required to reduce the risk of transmitting diseases. The Royal Society
for Public Health showed that the bacteria living within skin pores or under
fingernails can be forced to the skin surface after the act of rubbing the
hands together during washing. Many of the bacteria living on our skin exist
as clumps of cells which are broken up by soap and dispersed into smaller ones.
Thus, the importance of rinsing our hands to remove the soap and the dispersed
bacteria.
Why is hand drying so important? Because it complements the other side of
hand hygiene, washing, by ensuring that touch-contact-associated cross-contamination
is reduced to a minimum. Residual moisture left on hands that are not properly
washed and dried is the single most determinant factor for hand hygiene2.
For instance, about 60,400 bacteria are transferred to the skin of a person
who is touched with damp hands2. However, when hands are carefully
dried with a cloth towel for 15 seconds, the transfer of bacteria to skin is
reduced by 89%2.
How to dry our hands ? There are four main methods: paper towel; warm air
dryer; jet air dryer; and reusable cloth towel. Many people believe that there
is no significant difference between these methods or, if does exist, it is
only a matter of economics and/or environmental footprint.
So which method is the best ?
Although, there have been contradictions in the literature over the last
40 years, the majority of the studies conducted under realistic conditions
showed that the use of paper towel is the best drying method to minimize the
spreading of bacteria, compared to warm and jet air dryers3-8. Bacteria
are transferred from wet hands to the paper towel which reduces the number
of remaining bacteria on our hands9.
Some studies suggest that there are no significant differences between paper
towel and warm air dryers9-13, but two of them used unrealistic
long drying times of 45 seconds to one minute11-12. Ansari14 showed
that warm air dryers are better than paper towel. However, warm and jet air
dryers have the potential for depositing pathogenic bacteria onto the hands
and body as well as projecting them into the surrounding environment4-6,8.
A few studies3,4 showed that reusable cloth towels are slightly
more effective than paper towel or warm air dryers. However, when cloth gets
wet, its efficiency drops. Schwarz7 reported that bacteria are only
reduced by drying hands with absorbent materials.
The importance of hand drying with paper towel to prevent the transmission
of illness has also been recognized by the World Health Organization1 and the
Centers for Disease Control and Prevention (CDC)15 in the US. These
authorities recommend that hands be thoroughly dried using a paper towel.
Additionally, the behaviour of people in public washrooms has to be considered.
They rarely wash their hands for at least 15 to 20 seconds as recommended by
the CDC! Moreover, when people are in a hurry, they rarely use warm air dryers
long enough to ensure sufficient dryness and often complete the process by
wiping their hands on clothing5! This is generally true in crowded
places such as malls, movie theatres and airports. In summary, from the hand
hygiene perspective, the use of paper towel is the best drying method to minimize
the spreading of bacteria, compared to warm air dryer and jet air drier. Moreover,
when considering how people behave in public washrooms paper becomes even more
a preferred choice. For years we have been told 'wash your hands'. Now, we
have to adapt and say 'wash and dry your hands with paper towel'! TW
| Roger Gaudreault PhD is General Manager of Research & Development
with Cascades Canada Inc based in Kingsey Falls, Quebec. rgaudreault@cascades.com |
|
References: 1World Health Organization guidelines on hand
hygiene in health care: http://www.who.int/gpsc/en/; 2Patrick et
al., 1997; 3Blackmore and Prisk 1984; 4Blackmore 1989; 5Knights
et al. 1993; 6Redway et al. 1994; 7Schwarz 2006; 8Redway
and Fawdar 2008; 9Taylor et al., 2000; 10Davis et al.,
1969; 11Matthews and Newsom 1987; 12Meers and Leong
1989; 13Gustafson et al. 2000; 14Ansari et al., 1991; 15Centers
for Disease Control and Prevention: www.cdc.goc/handhygiene.
| The original text of this article was modified by error
when it was first shown on the web site. The text has now been corrected. |
|
