What Causes Burning Sensation In The Lungs After Working In A Paint Booth?

I've been a car spray painter all my working life. I'm now 66 and have more or less retired. I've been helping out a freind who has a garage over the last year in the paintshop, but have now sore lungs when I come home. I use my blue inhaler two or three times in the evening and it seems to alleviate the burning for a while although the discomfort still persists. Even being in the shop seems to bring it on. If I quit the shop altogether do you think it'll stop, or have I damaged my lungs permanently. Please help....