Mr D.T develops allergic reactions as a result of his job

Mr D.T recently changed job from painting to gardening in an industry. 

He became allergic on the job within one month of resuming the new role.  D.T's employers started to complain when he took one week off sick in his first month of resumption. His company’s health and safety manager organized for him to see an occupational health advisor for an assessment. It was discovered that his Mr DT was allergic to pollen grains. His new job brought him in contact with pollen and he suffered breathing problems. Does everyone with this job role end up this way?