Its not beyond the realms of possibility that a fireplace is constructed partly with asbestos.
No point worrying about it now. If it was asbestos, the damage will have been done. Unless you had a face fitted P3 spec particulate mask, you may as well have not bothered with a mask at all.
Your room is likely to be festooned with asbestos fibres (if it was asbestos). Best thing you can do to limit exposure to your family is open all the windows and beat everything to lift the fibres and hope the wind takes most of it out. Although, to be sure you’d have to spend alot of money on a cleanup team, or chuck all your possessions in that room out.
Hora eh? 😯 🙄