At a work place the daily exposure to a single chemical is as follows: Time Concentration (ppm) 100 8:00 a.m. to 10:00 a.m. 180 10:00 a.m. to 12:00 noon ( 1 hour lunch break from 12:00 to 1:00 pm) 220 230 1:00 p.m. to 2:00 p.m. 2:00 p.m. to 2:30 p.m. 2:30 to 4:00 p.m. 4:00 p.m. to 5:00 p.m. 190 160 The following exposure limits are given for the chemical: PEL = 210 ppm STEL= 600 ppm Are the workers overexposed to the chemical? Please show work for partial credit