Police were justified in using CS spray against juveniles at a Co Down children's home, a watchdog has found.
The Police Ombudsman also concluded that deploying the spray during other incidents in Ballymena and Londonderry had been lawful, necessary and proportionate.
Police Service of Northern Ireland (PSNI) Chief Constable George Hamilton routinely refers the use of CS spray against under 18s for independent investigation.
The incident at the children's home happened in January, when officers responded to reports of two teenagers damaging equipment and furniture.
Staff said the boys, aged 15 and 17, had smashed an alarm system, broken glass doors, destroyed furniture and flooded a corridor, before using a wardrobe to barricade themselves in a room with three female residents.
They also advised that the youths may have had weapons such as chair or table legs with protruding nails or screws, and a n officer who attempted to enter the room said a swipe was taken at him with a metal bar.
The youths were warned to drop any weapons and leave the room. They were also told on several occasions that CS spray would be used if they did not comply.
However, when warnings were ignored, an officer pushed his way into the room and used the spray, allowing his colleagues to restrain the two boys, before providing aftercare and taking them into police custody.
Staff at the home confirmed the police account of the incident, and raised no concerns about how the situation was handled.
Meanwhile, CS spray was used against a 17-year-old boy who had been detained by a member of the public after smashing a window in Londonderry.
Police said the teenager became violent and screamed wildly when officers tried to restrain him, and that using the spray allowed handcuffs to be applied.
Officers were also concerned the situation could escalate, because a crowd of youths had gathered nearby.
The member of the public who had reported the incident to police confirmed the youth had been acting aggressively and resisting police.
Investigators also examined the use of CS spray on a 17-year-old boy in Ballymena.
Police said he had come towards them with fists clenched and had ignored several warnings.
The youth later lodged a complaint about sustaining an eye injury when police put his face against the ground during arrest.
However, police accounts that the youth had a noticeable face injury before his arrest were confirmed by a civilian witness.
In his findings police ombudsman Dr Michael Maguire said that all the officers involved had been properly trained in the use of CS spray and concluded that their actions had been lawful, necessary and proportionate.