In general you should not spray someone with pepper spray unless they have committed an arrestable offense. If the person you are spraying has not done anything that is bad enough to get them arrested, then how can you justify spraying them with a weapon? The offense that they commit could be the reason they are being arrested.
Once sprayed with pepper spray, make the arrest and handcuff the suspect. Do a good search incident to arrest to look for any potential weapons that the suspect may have. Then you need to decontaminate the suspect. Turn their face into the wind and encourage them to be still and allow the air to blow the pepper spray away.
If you have access to a water hose or bottled water that can be used to rinse off the pepper spray too. Sometimes suspects may have a greater than normal reaction to pepper spray and sometimes they can even have trouble breathing. Carefully monitor the person until they are turned over to the jailor to insure they are breathing without difficulty. I like to call the paramedics to check the subject out before I transport so they can decontaminate the suspect and they can clear them of any allergic reactions or breathing difficulty. He’s your prisoner; you are responsible for him; that’s what the SGT Says.