Do not use chemicals, only soft cloths to avoid scratching or damaging the paintwork.
IRSAP Advises: https://www.youtube.com/watch?v=6KBtByQH6JU
First you have to vent the radiator. There is a dedicated section on https://www.irsap.com/en/support-en/irsap-consiglia-3/2096-how-to-vent-radiators.
Radiators per se have no emissions after they are switched on. However, especially in the new ignition season,the dust that accumulates between one tube and another during downtimes can spread throughout the room by convection. The solution is to dust them with a slightly damp cloth, preferably a microfibre cloth or a duster. There are specific dusters on the market whose shape makes this operation much easier.
Radiators usually do not require any special cleaning. It is sufficient to dust them periodically with a slightly damp cloth, preferably using microfiber one or a duster. There are specific dusters on the market whose shape makes this operation much easier.