Mould liability

The tenants in my property have used a drier in the laundry, un-ventilated for three months. This has led to a great deal of mould and peeling paint. Prior to this, the three-monthly inspection reports for this tenant were clear that there was no damage/mould anywhere in the house. The reports covering the six years before (for the previous tenants) also confirm this.

But, unknown to me, the EQC painting in this area seven years ago was substandard - so when there was excess unventilated moisture, mould grew and paint peeled. There is a strong communication trail from the property manager showing requests that the property be ventilated. There are also neighbour reports that the curtains and windows were never opened. And mould has also appeared in other very sunny rooms.

I accept the painting of the laundry is a contributing factor and my responsibility. But my property manager tells me that the tenants are not liable for anything at all. That’s because they “didn't understand” what they were doing and the initial paint job negates them fully. Yet they initially admitted liability. I’m very confused.