Asthma reccurence

I grew up in Shanghai, China with asthma, but it went away when I came to U.S. as a young adult and for the 25 years I was fine. A few years ago, I got a job and moved to Taiwan. The asthma showed signs of returning two years later.

I came back to the States last year for a long visit, had a cold and the asthma returned.

Now I am back in Taiwan and having the same asthma problem now.

I wonder if my asthma problem is caused by the different environment in Taiwan or if it just occured because I am aging.

I am considering moving back to the States, but that is a major operation and then again, my previous asthma occurence was back in the States.

Any information and suggestions from fellow asthma sufferers is welcome.