Easy to preach I know, but for my money I think your initial focus should be on the dust. Shavings and chips can be dangerous underfoot, or even cause you to lose the odd chisel or two in the heap!, but they don't directly kill.
I appreciate that your workspace is fairly well ventilated, but have you tried the fingertip test?
Wipe a shiny surface near the lathe clean, and then just 'lathe' (bit of turning and a bit of sanding) for half an hour or so, with the door open of course. And the causes of that no longer shiny surface is what's heading for your lungs.
It's all the micro bits of crud that mess with our bronchiae, cos we don't inhale the chips! (!! makes me sound like a non-smoking fanatic doesn't it?!).
I'm the first to admit that I didn't really follow this argument until I acquired a respirator thingy - I promise you will not believe the amount of crud that gets stopped, and that's the crud immediately around our heads as we 'lathe' away, stooping closer to gasp in awe and wonderment at our artistic wonderfulness, or as is often the case in my shed in total disbelief at what has appeared!, or indeed disappeared!!
Each time I take off the respirator and admire the crudpile, somehow the pain of the cost of purchase is lessened.
I think you have two areas to consider - one is the health of your lungs, and the second is the hassle of cleaning up lathe fallout. And doesn't it fall out!! Sackfuls!
On to the 'mechanics' - forget the chips, big chips means big suck. Big pipes, big extractors, big storage/filter volumes to handle big airflow etc etc. And pretty big money to do all that. (there are much more technical threads about this somewhere on here - well worth a search/look).
By it's very nature, turning sprays chips everywhere, and at speed! Very difficult to catch. But there is a chance of doing something to help catch the small stuff.
One of the manufacturers actually produces a hood-like structure for their lathes - I think it's Fox - you might get some ideas from that. And I think a certain CHJ has constructed a similar structure too. But I suspect that the micro crud handling is where it gets tricky
Hopefully he'll see this and point you in the right direction for further clues!
Final thought. You may have noticed a number of possible turning bargains on Ebay that have an unfortunate tale that the owner is no longer fit enough to use the kit. What they don't say is that quite a large number are due to breathing difficulties, made worse by the nature of turning.
