Both effects are the same depending on the severity of the Asthma. Asthma in the bad sense can cause weakening of the lungs and severe breathing difficulties such as needing home oxygen treatment all the time etc.
A short term effect is a consequence which happens in a short amount of time.A long term effect is a consequence which happens after a long period of time.
I'm not sure exactly what type of decision you are trying to find short term and long term for, but for business decisions short term is zero to three months, and long term is anything over a year.