Every industrial chemical has some safety concerns that need to be understood and properly addressed. Chlorine dioxide and it’s precursors are certainly no different. There are three primary safety concerns involved.
1. Chlorite or chlorate when allowed to dry are strong oxidizers and will cause a fire if they come in contact with organic materials (paper, cotton clothing, leather, hydrocarbons, etc.). It is sold only as an aqueous solution, and as long as it remains as such, it is safe to handle.
2. Chlorite and chlorate should be stored in separate containment areas from acids. Contact with acid will form chlorine dioxide gas. This is similar to bleach, which will form chlorine gas when mixed with acid.
3. Chlorine dioxide gas in air at concentrations at or above 10% is flammable. For this reason, properly designed chlorine dioxide generators will produce their ClO2 solutions at concentrations below about 3,000 ppm. This insures that if a spill or line break occurs, the solution is not capable of producing flammable concentrations in the atmosphere under worst case conditions with warm carrier water. See chart below which shows the safe concentration range for chlorine dioxide solutions of various temperatures.