If you spend a lot of time in the loft, you should strongly consider use of a quality mask. We all know that pigeons create a lot of dust, and has been known to cause breathing problems for a fancier. Foy’s sells an excellent mask with an exchangeable filter that does a great job (#737 Moldex Mask). A good fan that will pull out dust is a good idea along with as much ventilation as you can create. Vents near the floor level and then up near the ceiling will create a natural air flow.