Yes, lung function can be affected by thalassemia. Iron is one suspected cause but not the only cause.
Use of natural chelators as a supplement to chelation may have some value as they penetrate all tissue in the body. These include IP6, green tea extract and wheatgrass. Wheatgrass may also have some value for asthma in general. In my own cae, both my asthma and allergies have been less severe since I began seriously addressing my low vitamin D level.