WTC OSHA Silica Sampling Data for West Area

Please Note:

The PEL for Respirable Dust containing crystalline silica (quartz) is determined individually for each sample, using the following formula:

PEL = 10mg/m3 ÷ (%SiO2+2), where %SiO2 refers to the amount of crystalline silica measured in that sample.

This calculated PEL is compared with the Respirable Dust sample result to determine whether there is an overexposure. According to this formula, if there is no crystalline silica found in a sample, the PEL for that Respirable Dust sample is 5.0 mg/m3. As the formula implies, the PEL for respirable dust containing crystalline silica varies depending on the concentration of crystalline silica in the sample. The higher the concentration of crystalline silica the lower the PEL. (Click here for more information on the crystalline silica and the OSHA PEL.)

The Particulates not otherwise regulated (Respirable Fraction) OSHA permissible exposure limit (PEL) is 5.0 mg/m3.

aOther forms of crystalline silica (cristobalite) have not been detected in WTC samples. bResults are averaged and reported for the time duration stated. cND = Crystalline Silica None Detected.
Date Taken Operation Sample Type Duration (min) Respirable Dust TWAb mg/m3 Crystalline Silicaa (Quartz)c %b PEL mg/m3 (based on formula) Respirable Dust TWAb >PEL?
04/20/02   Area 365 0.110 32.00 0.294  
04/18/02   Area 503 0.041 ND 5.000  
04/18/02   Personal 320 0.079 ND 5.000  
04/18/02   Personal 188 0.650 39.00 0.244 YES
04/18/02   Personal 455 0.420 25.00 0.370 YES
04/15/02 AREA SAMPLE Area 467 0.049 ND 5.000  
04/15/02 AREA SAMPLE Area 327 0.099 ND 5.000  
04/11/02   Personal 457 0.340 ND 5.000  
04/11/02   Personal 456 0.190 14.00 0.625  
04/11/02   Personal 454 0.480 6.10 1.235  
04/11/02   Personal 487 0.320 9.10 0.901  
04/11/02   Personal 452 0.065 ND 5.000  
02/24/02   Personal 405 2.200 3.00 2.000 YES
02/24/02   Area 465 0.100 ND 5.000  
02/24/02   Area 465 0.046 ND 5.000  
02/24/02   Area 460 0.000 ND 5.000  
02/19/02 LABORER Personal 492 0.390 6.70 1.149  
02/13/02   Personal 435 0.470 ND 5.000  
02/11/02   Personal 435 0.110 ND 5.000  
02/11/02   Area 420 0.190 ND 5.000  
02/10/02   Personal 92 0.280 ND 5.000  
02/08/02 GRAPPLER Personal 454 0.130 ND 5.000  
01/29/02   Area 385 0.048 ND 5.000  
01/21/02 AREA SAMPLE Area 480 0.120 ND 5.000  
01/21/02 DRILLER Personal 385 0.160 ND 5.000  
01/19/02   Area 430 0.000 ND 5.000  
01/17/02   Personal 447 0.230 ND 5.000  
01/17/02   Personal 451 0.210 ND 5.000  
01/17/02   Area 410 0.063 57.00 0.169  
01/17/02   Area 388 0.055 ND 5.000  
01/17/02   Area 361 0.130 ND 5.000  
01/16/02   Area 270 0.055 ND 5.000  
01/11/02   Area 305 0.083 ND 5.000  
01/11/02   Area 310 0.160 28.00 0.333  
01/11/02   Area 285 0.130 ND 5.000  
01/11/02   Personal 90 0.150 ND 5.000  
01/09/02 LABORER Personal 377 0.018 ND 5.000  
01/05/02 AREA SAMPLE Area 375 0.160 ND 5.000  
01/04/02 AREA SAMPLE Area 305 0.130 ND 5.000  
01/04/02 AREA SAMPLE Area 305 0.079 ND 5.000  
01/04/02 AREA SAMPLE Area 383 0.160 12.00 0.714  
01/04/02 AREA SAMPLE Area 400 0.180 ND 5.000  
01/04/02 DOCKBUILDER Area 180 0.470 14.00 0.625  
01/03/02 DOCKBUILDER Personal 143 1.800 3.80 1.724 YES
01/03/02 AREA SAMPLE Personal 154 0.120 ND 5.000  
01/03/02   Personal 362 0.094 ND 5.000  
01/03/02   Personal 375 0.099 ND 5.000  
01/03/02   Area 240 0.061 ND 5.000  
01/03/02   Area 415 0.110 ND 5.000  
01/03/02 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 410 0.160 ND 5.000  
01/03/02   Area 300 0.000 ND 5.000  
01/02/02   Personal 205 0.000 ND 5.000  
01/02/02   Personal 172 0.990 15.00 0.588 YES
01/02/02   Personal 420 0.240 ND 5.000  
01/01/02   Personal 350 0.068 ND 5.000  
01/01/02   Personal 318 0.100 ND 5.000  
01/01/02   Personal 344 0.044 ND 5.000  
01/01/02   Personal 458 0.077 ND 5.000  
12/29/01 AREA SAMPLE Area 405 0.074 ND 5.000  
12/27/01   Area 408 0.026 ND 5.000  
12/26/01   Area 423 0.100 ND 5.000  
12/26/01   Personal 422 0.130 ND 5.000  
12/20/01 GRAPPLER Personal 410 0.047 ND 5.000  
12/20/01 GRAPPLER Personal 380 0.043 ND 5.000  
12/20/01 GRAPPLER Personal 400 0.043 ND 5.000  
12/20/01 LABORER Personal 423 0.015 ND 5.000  
12/19/01   Personal 359 0.130 26.00 0.357  
12/19/01   Area 420 0.240 ND 5.000  
12/19/01   Area 545 0.120 ND 5.000  
12/19/01   Area 429 0.180 ND 5.000  
12/19/01   Personal 359 0.078 ND 5.000  
12/19/01   Area 391 0.029 ND 5.000  
12/18/01   Area 377 0.032 ND 5.000  
12/18/01   Personal 359 0.050 ND 5.000  
12/18/01   Area 384 0.200 ND 5.000  
12/18/01   Area 395 0.230 ND 5.000  
12/14/01 DOCKBUILDER Personal 198 0.180 21.00 0.435  
12/10/01   Personal 456 0.072 26.00 0.357  
12/04/01   Personal 320 3.900 ND 5.000  
12/04/01   Personal 175 0.061 ND 5.000  
12/04/01   Area 310 0.130 ND 5.000  
12/01/01 AREA SAMPLE Area 280 0.034 ND 5.000  
12/01/01 AREA SAMPLE Area 290 0.029 ND 5.000  
11/28/01 AREA SAMPLE Area 365 0.110 ND 5.000  
11/25/01   Area 330 0.046 ND 5.000  
11/23/01   Area 440 0.046 ND 5.000  
11/19/01 AREA Area 360 0.200 10.00 0.833  
11/18/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 337 0.110 ND 5.000  
11/18/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 327 0.290 ND 5.000  
11/17/01 AREA SAMPLE Area 221 0.061 ND 5.000  
11/17/01 AREA SAMPLE Area 67 0.035 ND 5.000  
11/16/01 CRANE OPERATOR Personal 358 0.160 ND 5.000  
11/14/01 OPERATING ENGINEER Personal 305 0.066 ND 5.000  
11/13/01 IRONWORKER/TORCH CUTTER Personal 370 0.830 ND 5.000  
11/13/01   Area 345 0.720 ND 5.000  
11/04/01 LABORER Personal 405 1.100 ND 5.000  
10/30/01 LABORER Personal 292 0.061 ND 5.000  
10/30/01 EXCAVATING ENGINEER Personal 344 0.190 ND 5.000  
10/29/01 CRANE OPERATOR Personal 212 0.044 ND 5.000  
10/27/01 EXCAVATOR OPERATOR Personal 386 0.210 ND 5.000  
10/27/01 EXCAVATOR OPERATOR Personal 372 0.140 ND 5.000  
10/23/01 GRAPPLER OPERATOR Personal 378 0.033 ND 5.000  
10/23/01 GRAPPLER OPERATOR Personal 430 0.120 ND 5.000  
10/23/01 WATER TRUCK OPERATOR/GENERAL LABORER Personal 335 0.100 ND 5.000  
10/22/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 405 0.150 ND 5.000  
10/21/01   Area 407 0.051 ND 5.000  
10/19/01 TORCH CUTTING STEEL BEAMS WEST AREA OF PILE WTC-1 Personal 412 0.320 ND 5.000  
10/18/01 TORCH CUTTER/BURNING Personal 384 0.044 ND 5.000  
10/15/01   Area 240 2.300 ND 5.000  
10/13/01   Area 420 0.000 ND 5.000  
10/11/01 CRANE OPERATOR/OPERATING ENGINEER Personal 320 0.020 ND 5.000  
10/11/01 CRANE OPERATOR/OPERATING ENGINEER Personal 300 0.200 ND 5.000  
10/11/01   Area 420 0.000 ND 5.000  
10/10/01 GENERAL LABORER/SPOTTER Personal 278 0.120 ND 5.000  
10/10/01 IRONWORKER-BURNER/CUTTER Personal 281 1.500 ND 5.000  
10/09/01 IRONWORKER-BURNER/CUTTER Personal 365 0.830 ND 5.000  
10/09/01 CRANE OPERATOR/OPERATING ENGINEER Personal 328 0.170 ND 5.000  
10/08/01   Area 287 0.110 ND 5.000  
10/06/01   Area 309 0.310 ND 5.000  
10/05/01   Area 243 0.190 ND 5.000  
10/04/01   Area 466 0.470 ND 5.000  
10/03/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 154 0.210 ND 5.000  
10/01/01 LABORER-CLEAN UP Personal 380 0.720 ND 5.000  
09/29/01 GRABBER/CLAW OPERATOR/OPERATING ENGINEER Personal 310 0.018 ND 5.000  
09/29/01 CRANE OPERATOR/OPERATING ENGINEER Personal 250 0.022 ND 5.000  
09/29/01 IRONWORKER-BURNER/CUTTER Personal 385 0.990 ND 5.000  
09/28/01 IRONWORKER-BURNER/CUTTER Personal 235 0.480 42.00 0.227 YES
09/28/01 CRANE OPERATOR/OPERATING ENGINEER Personal 283 0.030 ND 5.000  
09/27/01 BOBCAT OPERATOR Personal 345 0.044 ND 5.000  
09/27/01 LABORER Personal 234 0.240 ND 5.000  
09/26/01 IRONWORKER-BURNER/CUTTER Personal 270 0.970 ND 5.000  
09/25/01   Area 235 0.022 ND 5.000  
09/24/01 LABORER-CLEAN UP Personal 240 1.200 2.00 2.500  
09/24/01 CRANE OPERATOR Personal 180 0.000 ND 5.000  
09/24/01 LABORER Personal 297 0.083 ND 5.000  
09/24/01   Area 240 0.140 ND 5.000  
09/23/01   Area 219 0.130 ND 5.000  
09/17/01   Area 247 0.000 ND 5.000