I tumble dry most of the washing (except on sunny days) as we've found since getting a tumble drier DD1's asthma has been MUCH better (no trips to A&E for nebs) due to the lower level of dust and damp.
Prior to the tumble drier I always had 3 clothes horses of washing lurking about in the living room and the house was really damp(used to have a dehumidifier running as well!). The amount of dusting has dropped too .
I know it's not great for the environment/my purse but neither is having to rush DD1 to local hospital every few weeks and then her having to be transfered to the big hospital by ambulance. DH then has to follow in car with DD2 & DD3, park the car in the £2 per hour car park (after paying for parking outside local hospital as well) and we all wait around for hours until Drs decide DD1 is well enough to go home. Costs upwards of £25 each time DD1 has an asthma attack just for petrol/parking let alone what the NHS's costs for nebs/ambulance/Drs & nurses time.
I figure the tumble drier is saving everyone money