I think that stricter laws against indoor pollution will help prevent things like lung disease. A lot of people this day and age are aware of the dangers of something like smoking. And I think that is the cause for the reduced numbers of smokers. But I think that there is still the danger of second-hand smoke.
I think overall the less pollution in the air the healthier it is for everyone, so some tighter regulations that cut down on the amount of toxins you are breathing in will reduce diseases such as Lung disease, I think it is very sensible to implement more regulations for cleaner air indoors and outdoors.
It has been said and supported by evidence now that indoor air pollution is perhaps even worse than outdoor pollution. So yes, tighter indoor air pollution regulations would cut down on lung disease. How to enforce these laws would be an entirely different story. There would have to be some sort of unit, like an air conditioner, installed everywhere.
As with any law, even if it does not have widespread adoption or following, there is going to be at least some effect made by increasing or tighting regulations. One obvious example would be indoor smoking, whereby it may be possible to reduce second hand smoke by regulating the way people smoke.
No, righter indoor air pollution regulations would not significantly reduce lung disease, because lung disease is not primarily caused by indoor air pollution. It is also impossible to police everyone's air inside their homes. Now that we have to all buy health insurance, people might not have the money left to pay for air quality.