Norovirus, and Bleach Dilution For Sanitization

2012 January 13
by Daniel Lakeland

If you have small children, especially in daycare, eventually you will be exposed to a wide variety of illnesses. One of the least fun is viral gastroenteritis caused by norovirus.

Norovirus is not susceptible to alcohol hand sanitizers due to its durable protein coat, and the main method for sanitizing surfaces that have been exposed is the use of bleach.

Sources I read online suggest that 1000 ppm bleach (1:50 dilution) is effective for surfaces like countertops, toilets, and other durable surfaces, 200 ppm (1:250 dilution) is recommended for things that come in contact with food or human mouth (like baby toys etc). These dilutions are MUCH less concentrated than the average person might think. If you have a typical say 500ml bottle you’re talking about putting in about 10ml (two tablespoons) of bleach and filling the rest with water for the strong solution, and 2 ml of bleach with the rest water for the weaker solution (half a tablespoon). Bleach solutions lose their effectiveness in a matter of days due to offgassing and reactions caused by light. One source said 30 days for complete ineffectiveness. If you’re in an institutional setting they recommend pouring out old bleach and making a fresh solution each morning.

The best way to apply it is via a wash bottle which does not aerosolize the bleach and therefore keeps it out of your mucous membranes and lungs etc. Do NOT use a normal squeeze spray bottle due to the possibility of breathing in irritating bleach droplets from the air which then makes you irritated and more susceptible to illness.


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