Occupational exposure was defined as minimum five
years employment in a xerographic unit. Male and female
operators in the age group of 20 to 60 years with at
least 5 years exposure to emissions from photocopiers
were included in the exposed group. Cumulative exposure
to photocopiers was calculated from the number of
working hours/day and number of working days/week
Exposure was assessed by the amount of time spent in
photocopier centers.
No. of hours exposed = No. of working hours/day ×
No. of working days/week × No. of years of exposure ×
50 weeks/year.