Oddly enough, diesel fumes and many substances with a nasty smell don’t seem to cause asthma, even though there is important evidence that they can cause allergic reactions in your nose.
If your asthma is due to your work then it should be possible to remove the cause. The fact that you have asthma from work means that others could also get it, so the discovery could help a lot of people including your employer.
If the asthma is discovered early, then your work environment can be improved, and the asthma treated, the result of which is usually a complete cure.
But if the occupational asthma is discovered after years of working with the offending materials, then it should get better when you no longer have breathe it in all day, but you are very likely to be left with permanent asthma, and this may be mild or severe asthma.
It is important to remember that asthma is so common that most people with asthma in a workplace have it for the same reasons as everybody else, and not because of their job.
This makes it hard to determine and discover the few people who really do have occupational asthma.
If you think that you have become affected by occupational asthma, then consult an expert on ‘Occupational Asthma’, or an allergist, as soon as possible.