Hello Renee, Unfortunately, Jim Humble has never shared how he came up with that idea, and testing does not support his idea...
I use a sanitizing spray around the house. Here is a test you can do. Mix up a solution by placing 10 ml of 5% sodium chlorite in a glass and adding 10 ml of 10% citric acid. Let this activate for 10 minutes, then pour it into a household spray bottle and add enough water to make 500 ml. You can use this to sanitize your bathroom surfaces, cutting boards, counter tops, and so on. Store it out of UV light and away from high temperatures. It will be yellow in color, and have the distinctive chlorine dioxide odor to it. If you have some chlorine dioxide test strips you can check the concentration of free chlorine dioxide in the solution. Come back in a month and the solution will still be yellow, have the chlorine dioxide odor, and have the same amount of free chlorine dioxide. The official statement on this from the commercial use of these products state 8 weeks, but my solution never lasts that long. Since I have never tested beyond 4 weeks, I just use that as my recommendation. Now, if you mix the same mixture and set it outside in the sunshine it will quickly loose all of the chlorine dioxide and end up colorless with no odor in a couple of hours. Chlorine dioxide is very unstable in UV light. The 28% concentration of sodium chlorite is dangerous to handle so I recommend diluting it down to a much safer 5% solution. If you want to make the sanitizing solution with 28% sodium chlorite you would use 38 drops of it (about 2.2 ml) and an equal portion of 10% citric acid. Tom
