#Negative ions generator#
#Negative ions trial#

#Negative ions generator#

A high voltage generator (Brandenburg Alpha III, Brandenberg, UK) was used to apply a DC potential between the pin electrodes and the earthed agar plate. In order to ensure uniform ionic exposure the agar plates were earthed and placed directly below a 7-pin electrode set, with the surface of the agar being 25 mm below the electrode tips. Cultures were exposed to positive air ions and negative air ions in separate experiments. Experimentation was undertaken on sessile cultures of Staphylococcus aureus (NCTC 10399/ATCC 13709), Mycobacterium parafortuitum (NCTC 10410/ATCC 19687), Pseudomonas aeruginosa (NCIMB 10848), Acinetobacter baumanii (NCTC 12156/ATCC 19606), Burkholderia cenocepacia (NCTC 10744/ATCC25609), Bacillus subtilis (NCTC 10106/ATCC33234) and Serratia marcescens (NCTC 1377/ATCC 274. In the study bacteria in pure culture on agar were exposed to air ions in a test rig, as shown in Figure 1. In this study seven bacterial species were exposed to both positive and negative ions in the presence of air for various durations and the bactericidal effects recorded. A study was therefore undertaken to clarify this issue and to determine the physical mechanisms associated with microbial cell death. the action of the ions, the production of ozone, or the action of the electric field) are responsible for cell death. In particular, it is not clear which of several possible mechanisms of electrical origin (i.e. However, while this body of work collectively suggests a biocidal effect in the presence of ions, in both air and nitrogen, the physical and biological mechanisms involved remain unclear. Over many years, various researchers have reported that 'air' ions inhibit the growth of Penicillium notatum, Neurospora crassa, Serratia marcescens, ' Staphylococcus albus', Candida albicans, Escherichia coli, Pseudomonas veronii, Aspergillus versicolor, Enterococcus malodoratus, Staphylococcus chromogenes and Sarcina flava. One characteristic of 'air' ions which has been widely reported is their apparent biocidal action.

#Negative ions trial#

In particular, results from a clinical trial in an intensive care unit suggest that negative air ions may have the potential to control some hospital acquired infections (HAIs). In recent years there has been renewed interest in the use of air ionisers to control the spread of airborne infection. The results of the study suggest that the bactericidal action attributed to negative air ions by previous researchers may have been overestimated. However in the case of Mycobacterium parafortuitum, electroporation resulting from exposure to the electric field appears to have been the principal cause of cell inactivation. With the exception of Mycobacterium parafortuitum, the principal cause of cell death amongst the bacteria studied was exposure to ozone, with electroporation playing a secondary role. This prevented both the electric field and the air ions from impacting on the bacteria, while allowing any ozone present to reach the agar plate. The second intervention involved placing an earthed wire mesh directly above the agar plates. In addition, the mica plate prevented ozone produced from reaching the bacteria. This intervention, while leaving the electric field unaltered, prevented the air ions from reaching the microbial samples. The first intervention involved placing a thin mica sheet between the ionisation source and the bacteria, directly over the agar plates.

In order to distinguish between effects arising from: (i) the action of the air ions (ii) the action of the electric field, and (iii) the action of ozone, two interventions were made. In the study seven bacterial species ( Staphylococcus aureus, Mycobacterium parafortuitum, Pseudomonas aeruginosa, Acinetobacter baumanii, Burkholderia cenocepacia, Bacillus subtilis and Serratia marcescens) were exposed to both positive and negative ions in the presence of air.

However, whilst the body of evidence suggests a biocidal effect in the presence of air ions the physical and biological mechanisms involved remain unclear. One characteristic of air ions which has been widely reported is their apparent biocidal action. In recent years there has been renewed interest in the use of air ionisers to control of the spread of airborne infection.