I am not familiar with the NZ tobacco availability. Since your body knows best what works with your biochemistry, you should certainly stay away from the mass market junk cigarettes which obviously cause you problems. Among the popular supermarket brands, Winston full flavor use additive free real tobacco (so they claim), although they are not organically grown i.e. regular pesticides and fertilizers were used (you would also need to clip the filter to avoid fibers).

If you do run into oldfashioned, additive free tobacco in some specialized tobacco shop there, it still may be worth rolling one or two to test the effect. For me, it works like magic (I especially noticed its positive effects during the last half a year, while I was getting the amalgams out). Instead of filters, use plain cigarette holder (you can even make one from suitable bamboo stick or some such), not the holders with chemical filters built in (unless they are removable). Alternatively, you can try a pipe (which looks pretty cool, to me).

When you have to roll your own, you smoke much less than with ready made cigarettes. Each cigarette becomes a kind of peaceful little ritual, very soothing for the soul. It's after all a sacred plant, gift of gods.

I also find the pure leaf smoke completely non-irritating (premade sticks make me cough). The natural smoke is competely bio-degradable since all life-forms, including our cells, have evolved mechanisms for metabolizing the natural/organic smoke for hundreds of millions of years. Those pictures of the so-called "smoker's lungs", all black and gunked up, they show on TV and to kids in schools are a shameless fraud (they are usually lungs of coal miners, full of coal dust).

If you check Colby's & Whitby's books, you will find that a surgeon or a pathologist can't differentiate the smoker lungs from non-smoker lungs. Biochemically they are different, of course, since smokers lungs have much more glutathione (and several other internal anti-oxidants and detoxifying enzymes). To the naked eye, though, they are indistinguishable.