As noted above, chlorine is less efficacious (at least in solu | Aprenda como utilizar o Dióxido de Cloro

As noted above, chlorine is less efficacious (at least in solution) compared to chlorine dioxide. Comparative studies have shown that chlorine forms more byproducts from reaction with various organic compounds than do either ozone or chlorine dioxide (41). Ozone is substantially less stable (in both air and water) than chlorine or chlorine dioxide, hence it would be more difficult to maintain a concentration over a prolonged period of time than chlorine or chlorine dioxide.

There is limited information with all of these agents with respect to the target organisms under consideration, including bacterial spores.

Factors and Challenges to be Considered in Determining a Decontamination Strategy
A basic task in developing a decontamination strategy is the setting of a target cleanup level. This task – defining “how clean is clean” – is conceptually no different than faced in other aspects of environmental remediation. For the particular aspects of biological warfare agents (as well as chemical agents), a framework for this decision can be set up using risk based principles. Like other applications, the residual acceptable risk level must be set after incorporation of the views of stakeholders (37). This task requires the inevitable recognition that absolute certainty of absolute building cleanup is impracticable.

From an acceptable risk level, a value for the amount of residual biological agent (e.g., anthrax spores) that would be tolerable can be developed providing that information on the agent dose-response as well as exposure factors (e.g., breathing rates) are available. For most of the agents considered it might be necessary to rely upon animal data to assess target levels. Principles of quantitative microbial risk assessment have been developed, including by myself and colleagues (19). For some organisms it has already been shown that animal data provide good estimates of human risk (20, 21). There is animal dose response data for Bacillus anthracis that could be used to form the basis for development of target levels (5, 11, 15).

Once a target level of microorganisms is stipulated, then given an estimate of the initial level of contamination, the ratio of these two numbers defines the degree of removal or inactivation that a decontamination system must achieve. As an example, if a particular room is estimated to have been contaminated by 100,000 spores, and if a final target level of 10 spores is deemed allowable (i.e., produces a sufficiently low risk), the a reduction of 99.99%, or 4 logs, must be achieved.

Given the degree of reduction that must be achieved, the required chemical concentrations and times need to be estimated from information on the rates of inactivation. This requires experimentation (likely using small-scale facilities) with the target organism(s) or suitable simulant(s). The objective of these studies would be to determine combinations of concentrations and times that result in the required degree of inactivation. This needs to be assessed as a function of temperature, humidity, and other factors that might influence the performance of the process. There is a large knowledge base on estimating kinetic parameters of disinfection processes (primarily in water and food applications) that is readily transferable to the problem of building decontamination(17, 18, 36). The results of these studies would have general significance, and once basic inactivation information was obtained, would not need to be repeated for each particular required decontamination event.

The results of these experiments would allow determination of the concentration of decontaminant that must be attained at every point at which microbial inactivation is needed. This concentration must be maintained for the required time to give the desired degree of inactivation. One of the important questions in implementation would be how much of a particular chemical (e.g., chlorine dioxide) needs to be fed into a building to achieve kill.