At any point during the course of a person's work life, he or she could become impaired. A 1990 study by E. I. du Pont de Nemours and Company found that just one-third of the company's disabled workers were disabled at the time of hire. The share of severely disabled people with a job increased from 23 percent to 26 percent over the time period. Since many disabilities appear with age, disabled workers are older than other workers. Almost half of nondisabled workers are under age 35, compared with 30 percent of mildly disabled and 28 percent of severely disabled workers.
Age also varies by type of disability.
The median age of the disabled population aged 18 to 64 is 42, compared with 36 for the general population, finds an analysis of 1990 SIPP data by Michele Adler of the Department of Health and Human Services. Adler also finds large differences in the share of disabled people who are employed, depending upon the type of impairment they have. Almost half of those with bad backs and visual impairments were employed, as were nearly two-thirds of those with hearing impairments. Disabled workers are more likely than others to work part-time, which explains some of the earnings difference between them and other workers. Education explains some of the earnings difference, too.