General Guidelines for Effectiveness & Safety
Consumer-level Chlorine Dioxide products have a high range of safety for human health and the environment. Below are general principles for use with many Chlorine Dioxide products.
Do carefully read your product’s label to learn specific guidance for that particular product. Stronger precautions may be listed on the label, and should then be followed instead. The guidance listed here should not be regarded as authoritative or expert.
Double-check measurements for ingredients
Most consumer-level products come in user-friendly packaging and with fairly straightforward mixing requirements, and some types of commercial products are also packaged for easy mixing.
Amounts to mix are different for each product. Figuring appropriate amounts to mix can be very complex for some commercial products, particularly when mixing small or extra-large batches. It is useful to write down amounts and double check them before mixing. You can use calculators on the internet to convert measurements between units, where needed.
If desired, you can buy test strips to monitor concentrations, but need to be sure to buy ones that work with the particular product you are using.
Keep careful track of “activation” time when mixing
Some Chlorine Dioxide products are "activated" by combining Sodium Chlorite (which is not the same as Sodium Hypochlorite) with a small amount of acid, such as citric acid.
If a product requires you to mix ingredients, read instructions and add ingredients in the order specified, and carefully allow correct amount of time between adding the next ingredient. Waiting too short of too long of time impacts the level of activation and how strong the resulting solution will be. Check instructions to see if you need to wait some time after mixing, or if you can use right away.
Do not inhale gas when mixing
When Chlorine Dioxide is being initially “activated”, it releases a strong fume, which should not be inhaled. Gas fumes will stop releasing potently when you add water to the activated mixture. If you are mixing large amounts, work in a well-ventilated area.
Use products designed for non-occupied areas only in non-occupied areas
“Shock” or “bomb” or gassing products that release in 24 hours or less should ONLY be used when an area is unoccupied. The room should be aired out afterwards before people enter.
If a handheld fogger of high-concentration disinfectant is being used, people in the area should use appropriate PPE.
Maintain appropriate concentration levels in air
When using a slow-release (multi-day) deodorizer product, be sure the room is large and there is enough ongoing air flow so that the concentration will continually be low.
In appropriate amounts, Chlorine Dioxide can be applied to the air via humidifiers or HVAC systems in occupied rooms, to disinfect air and surfaces. Ultrasonic humidifiers are ideal. Treatment will be more effective if the humidity level in the room is high—preferably 45-65%. (Distilled water should be used in these if you may be sensitive to minerals in air.)
Note: Humidity itself also helps reduce virus transmission and provide moisture that helps your body repel pathogens. However, humidifiers can grow significant harmful bacteria if not thoroughly disinfected at least every three days. Simply adding even a small amount of Chlorine Dioxide in the humidifier tank will prevent that concern, prevent biofilms from forming, and help avoid mold problems.
How can you know how much Chlorine Dioxide to put in a humidifier?
Professionals can provide consultations for large areas, and Chlorine Dioxide test strips can help to check air concentrations and distribution. [More info to be added later as available.] NIOSH recommends an exposure limit of 0.1 ppm volume (which is different than the ppm in the liquid mix being used) over the course of an 8-hour work day, or 0.3 ppm for 15-min. exposure.
[A potential innovation that would be helpful: A product manufacturer could offer an interactive website or video and phone assistance to help users determine the right amounts for specific rooms.]
Be sure Chlorine Dioxide will make direct contact with germs
Spraying will not be effective if mist is not close enough or dense/thick enough to drift onto surfaces.
Also, disinfection will not occur in gaps between droplets. You may wish to also spread liquid more fully over some surface areas using your hand or a dampened cloth.
Protect from sunlight, heat, moisture, and excessive shaking
UV rays from sunlight cause Chlorine Dioxide’s chemical actions to accelerate greatly. Its effectiveness will be used up very quickly if it is kept exposed to sunlight. Store it protected from sun, and always keep it in non-transparent containers, or keep containers covered well.
To prevent chemical activity from speeding up and becoming depleted or bursting the container, do not store in hot environments such as parked cars.
Prevent condensation from reaching materials prior to use. Moisture may start premature activation.
Avoiding vigorous stirring and pouring, and keeping a lid on containers will also help Chlorine Dioxide gas stay in liquid solutions longer and extend the life of the product.
Dispose of leftovers
Chlorine Dioxide's chemical activity level decreases over time. The effectiveness of most products that involve mixing to activate is usually substantially reduced within 5 to 14 days after mixing. Some products are effective for longer times. Read the product descrition to see how long a specific product is formulated to be effective. When you activate a product, write an appropriate “expiration date” on the container.
Try to only mix the amount you know you will use in the next several days, and mix up more later if needed. Do not be tempted to keep a liquid mix after your expiration date; it may no longer kill pathogens sufficiently.
Once Chlorine Dioxide’s activity level has decreased, it is relatively safe for the environment, as it mostly turns to inert salt. To neutralize it further, you can put any leftover mix in sunlight for an hour, and then pour it down the drain.
If you get a high concentration in your eyes, rinse them thoroughly.
Accuracy of basic concentration levels is highly important because of Chlorine Dioxide's high potency, and different parts of the body have different sensitivities to Chlorine Dioxide.
However, for eyes, Chlorine Dioxide is actually classed as only a mild irritant at low concentrations. The effect is mild enough that Chlorine Dioxide is used as a disinfecting ingredient in some contact lens care solutions.
Don’t use over-concentrated mixes for the wrong type of use
Do not use Chlorine Dioxide at higher levels of concentration than are recommended for that specific purpose for that specific product. If a lower concentration is needed, appropriately dilute a small portion of the more concentrated mixture.
Chlorine Dioxide’s potency is fairly consistent across broad pH and temperature ranges, though adjustments should be made for any highly specific situations. (It also retains its potency better in somewhat dirty water than some other disinfectants.)
You do not need to rinse
Let surfaces air dry after applying Chlorine Dioxide. It kills pathogens rapidly, but allowing Chlorine Dioxide liquid mixes to air dry after applying gives it maximum time for best effectiveness, and gives time for chemical to turn more inert. Chlorine Dioxide liquid mixes will not leave noticeable or harmful residue, and effects on skin are mild, so they do not need to be rinsed off.
(Fresh produce should only be treated with very low-level ~5 ppm concentrations. Optionally, after appropriate contact time they may be rinsed off for taste reasons.)
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If precautions listed on a more authoritative document or on a particular product are stronger, you should follow the stronger precautions.
The US EPA's RED document for Chlorine Dioxide and Sodium Chlorite lists some ranges of concentrations (which must be adjusted depending for every specific product's customized formulation) and specific safety limits for various uses of Chlorine Dioxide.
Visit our Related Studies page for additional research, data and government guidelines for more information on safe, effective uses of Chlorine Dioxide.