The world has a love/hate relationship with ozone. Ozone (O₃) is a “super” oxidizer, almost as reactive as fluorine. This reactivity makes ozone either desirable or undesirable, depending on the situation.

As a process chemical, ozone has utility for chemical synthesis, in disinfection of water and waste streams, and in product cleaning.¹ As a constituent of the atmosphere, the levels, trends, and balance of ozone are of environmental concern. Regulations at the local, national, and global level that are designed to prevent or reverse environmental deterioration have had the effect of restricting available options for critical cleaning processes.

GOOD OZONE
Through decades of media reporting, virtually everyone has become aware of “the ozone layer,” a region in the stratosphere, about 6–30 miles above the surface of the earth. The ozone absorbs about 98% of the UV light. This is important because UV light is potentially damaging to living things. Historically, most scientists agree that the concentration of stratospheric ozone has been in dynamic equilibrium. However, chemicals used in manufacturing that are sufficiently stable to be carried by air currents to the stratosphere have disrupted this equilibrium, with a net reduction of O₃. This in turn leads to higher ground level UV radiation and to ecological imbalance.

The Montreal Protocol, enacted in 1989, is a global response to concerns with this ecological imbalance. The Montreal Protocol restricts the production, importation, and use of a number of chemicals that have the potential to destroy stratospheric ozone. Initially, chemicals referred to as Class 1 ozone depleters, with the highest Ozone Depletion Potential (ODP), including chlorofluorocarbons (CFCs) and 1,1,1-trichloroethane, were phased out. Both compounds were widely used as solvents for industrial cleaning.

Understandably, many manufacturers searched for a mythical “drop-in” replacement that would have no impact on the technical aspects of their manufacturing processes. To minimize the impact on process performance, some manufacturers adopted hydro chloro - fluorocarbons (HCFCs) that, although less damaging to the ozone layer than Class I ODCs, still have a significant ODP. Many of these Class II ODCs have either already been phased out (notably HCFC-141b) or will be within the next few years. For example HCFC-225 will be subject to a production and usage ban in 2015. However, in the United States, manufacturers could continue to use stockpiled or recycled material for critical cleaning.² In implementing process changes, manufacturers must be aware of the potential impact of these necessary environmental restrictions on product quality, surface contamination, and leachable residue.