'Officers use spray at their discretion. It stops people by causing eyes to burn'
Irritant spray, called CS spray or Pava spray, is used on a fairly frequent basis by officers and is one of the items in the police 'toolkit'.
Exposure to the gas causes a burning sensation and tearing of the eyes to the extent that the subject cannot keep them open and are thus often incapacitated.
There follows a burning irritation of the nose and throat causing coughing, disorientation and difficulty breathing. Effects last around 20 minutes.
A long-serving PSNI officer explained that there are no set rules for the use of CS spray, unlike the way strict guidelines are in place for the use of batons, guns or Tasers.
"Individual officers make their own decisions, using their own judgment, about the situation they find themselves in.
"They might use their hands to grab or hold someone back.
"On another occasion a baton might be needed to deal with a violent or potentially violent person who is posing a threat to them, to a member of the public or to a colleague," the officer added.
"The substance works best on moist areas of the victim's body, especially the eyes and mouth."
"It's a squirt of liquid directly aimed at the face of one person, not a fine spray that envelops a group of people," the officer revealed.
"It will usually stop someone straight away. They will be incapacitated by the effect of the liquid in their eyes.
"You have to be careful in using it that you don't spray someone else by mistake or one of your colleagues.
"This can easily happen if you are in a fast-moving situation like a brawl where there's a lot of pushing and shoving.
"I have been sprayed in the face myself by Pava during a training demonstration and it really stings." The officer added that using the spray is not regarded as a big deal.
But officers who use it will always be required to fill out a 'use of force' form.
The last time an incident involving CS spray was referred to the Police Ombudsman was in June last year in relation to an incident involving a youth.