Isocyanate (typically in 2-pack paints) is the most common cause of occupational asthma. It also causes dermatitis.
It affects workers spraying 2-pack (2K) isocyanate paints in motor vehicle repair and in motor and semi-trailer manufacture.
See COSHH Essentials for detailed advice on control.
You breathe isocyanate mist when you raise your BA visor to check the paint film quality, or prime or wash out the gun by spraying without wearing BA.
Check that the air-fed BA and working procedures are effective enough by measuring your exposure using biological monitoring.
Maintain the booth and BA regularly and keep unprotected persons out of the spraying areas.