Police are considering using a more concentrated form of pepper spray.
The evaluation will compare its effectiveness with the current version of oleoresin capsicum which has the lowest concentration of capsicum available.
This follows a trial in the Bay of Plenty police district.
The new spray has six times more capsicum, a more immediate impact and takes slightly longer to wear off.
Operational services national manager Inspector Jason Ross says the use of oleoresin capsicum spray has become more common and has seen a corresponding levelling off in its effectiveness over time.
"This is consistent with our own research and what has happened internationally among other police jurisdictions, the vast majority of whom have already moved to the enhanced spray."
Police had tried different spray configurations during the trial including a liquid stream spray and a gel version.
Feedback from staff about the new spray has been very positive.
But it was important to try different spray configurations in a range of situations to find the most effective option for staff and public safety, he says.
Oleoresin capsicum spray was used nationally 1505 times from July 1, 2012 to June 30 this year.
The new version of the spray has been deployed 119 times in seven months during the Bay of Plenty trial.
Mr Ross says monitoring of current oleoresin capsicum spray indicated that while it was still effective in the significant majority of incidents, there was room for improvement.
International experience has shown the stronger spray to be more effective in subduing someone who is acting aggressive or violent.
Communication still remains an officer's most powerful tool though there will inevitably be times when the situation necessitates more force being used, Mr Ross says.
Oleoresin capsicum spray is still an effective and important tactical tool for police with the lowest level of injuries, he says.
The new spray works in the same way so there will be little or no change required to current training and tactics.
The evaluation is earmarked for completion by the end of the year.
- © Fairfax NZ News
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