Even if phosgene was created during a leak repair, if he's been ventilating the room with fans it's long gone. I've worked with various refrigerants for 20 years with no effects like you're describing. I've been hit with phosgene several times (including when a compressor blew it's terminals while I was standing next to it, bathing me in burning refrigerant and oil). The effect is strong but clears immediately when you get fresh air.
I suspect you're getting irritated by insulation, dust or mold that was disturbed during the repair, or some other environmental contaminant. I also agree with the mental thing, you might just be working yourself up. Have a duct cleaning/inspection done.
Good? Bad? I'm the guy with the gun.
Statements made by me are strictly my opinions and do not reflect the opinions of my employer. I am not authorized to make any official statements on behalf of my employer.
Any technical advice offered by me is for educational purposes only, all HVAC related repairs should only be attempted by qualified personnel.