WTC OSHA Silica Sampling Data for Southwest 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?
05/05/02 Personal 450 0.260 ND 5.000
05/03/02 Personal 512 0.000 ND 5.000
04/25/02 AREA SAMPLE Area 482 0.089 ND 5.000
04/25/02 AREA SAMPLE Area 480 0.000 ND 5.000
04/19/02 Area 424 0.035 ND 5.000
04/17/02 Area 461 0.072 ND 5.000
04/17/02 Area 453 0.088 ND 5.000
04/17/02 Area 473 0.072 ND 5.000
04/17/02 Area 451 0.094 ND 5.000
04/17/02 Area 449 0.063 ND 5.000
04/15/02 Personal 482 0.072 ND 5.000
04/15/02 Personal 457 0.240 ND 5.000
04/15/02 Personal 452 0.340 12.00 0.714
04/03/02 Personal 440 0.280 9.20 0.893
04/02/02 Area 408 0.020 ND 5.000
04/02/02 Area 424 0.000 ND 5.000
04/02/02 Area 422 0.054 ND 5.000
04/02/02 Area 422 0.190 ND 5.000
03/19/02 Personal 443 0.080 ND 5.000
03/10/02 Personal 355 0.120 ND 5.000
03/10/02 Personal 435 0.064 ND 5.000
03/10/02 Personal 425 0.150 ND 5.000
03/10/02 Personal 435 0.039 ND 5.000
02/24/02 Personal 120 0.120 ND 5.000
02/21/02 Area 345 0.070 ND 5.000
02/19/02 Personal 480 0.840 5.60 1.316
02/17/02 LABORER Personal 465 0.017 ND 5.000
02/17/02 LABORER Personal 463 0.079 ND 5.000
02/17/02 LABORER Personal 273 0.000 ND 5.000
02/17/02 AREA SAMPLE Area 445 0.000 ND 5.000
02/15/02 NY FIRE DEPARTMENT Area 375 0.064 ND 5.000
02/15/02 AREA SAMPLE Area 365 0.000 ND 5.000
02/15/02 LABORER Personal 365 0.056 ND 5.000
02/13/02 Area 420 0.066 ND 5.000
02/13/02 Personal 360 0.000 ND 5.000
02/12/02 Personal 434 0.073 ND 5.000
02/10/02 Personal 445 0.110 ND 5.000
02/10/02 Personal 417 0.340 9.80 0.847
02/10/02 Personal 455 0.064 ND 5.000
02/10/02 Personal 475 0.100 17.00 0.526
02/10/02 Personal 435 0.068 ND 5.000
02/09/02 Personal 391 0.130 ND 5.000
02/09/02 Personal 387 0.084 ND 5.000
02/09/02 Personal 444 0.260 7.20 1.087
02/09/02 Personal 438 0.260 7.40 1.064
02/09/02 Personal 435 0.089 17.00 0.526
02/08/02 DOCKBUILDER Personal 418 0.190 15.00 0.588
02/08/02 DOCKBUILDER Personal 458 0.260 5.90 1.266
02/06/02 DOCKBUILDER Personal 401 0.370 12.00 0.714
02/06/02 DOCKBUILDER Personal 351 1.300 9.20 0.893 YES
02/06/02 DOCKBUILDER Personal 420 0.160 11.00 0.769
02/06/02 DOCKBUILDER Personal 213 0.400 15.00 0.588
02/05/02 LABORER Personal 400 0.140 ND 5.000
02/05/02 LABORER Personal 425 0.320 9.30 0.885
02/05/02 LABORER Personal 420 0.160 12.00 0.714
02/04/02 Personal 431 0.130 15.00 0.588
01/29/02 Personal 480 0.000 ND 5.000
01/29/02 Area 458 0.045 ND 5.000
01/28/02 Personal 460 0.037 ND 5.000
01/28/02 Personal 490 0.290 16.00 0.556
01/28/02 Personal 463 0.290 16.00 0.556
01/28/02 Personal 495 0.051 ND 5.000
01/28/02 Personal 506 0.033 ND 5.000
01/28/02 Personal 541 0.160 ND 5.000
01/28/02 Personal 519 0.024 ND 5.000
01/28/02 Personal 552 0.049 ND 5.000
01/25/02 TRUCK DRIVER Personal 480 0.070 ND 5.000
01/25/02 TRUCK DRIVER Personal 475 0.075 ND 5.000
01/21/02 TORCH CUTTER Personal 410 0.090 ND 5.000
01/21/02 TORCH CUTTER Personal 510 0.150 11.00 0.769
01/21/02 DRILLER Personal 510 0.013 ND 5.000
01/21/02 DRILLER Personal 480 0.620 8.10 0.990
01/21/02 DRILLER Personal 485 0.120 ND 5.000
01/19/02 Personal 445 0.000 ND 5.000
01/19/02 Personal 377 0.061 ND 5.000
01/17/02 Personal 389 0.042 ND 5.000
01/12/02 LABORER Area 440 0.076 ND 5.000
01/12/02 LABORER Area 252 0.150 ND 5.000
01/12/02 LABORER Area 504 0.093 ND 5.000
01/12/02 LABORER Area 453 0.094 ND 5.000
01/12/02 Area 436 0.120 ND 5.000
01/10/02 Personal 10 0.000 ND 5.000
01/10/02 Personal 10 3.500 ND 5.000
01/09/02 GRAPPLER Personal 493 0.087 ND 5.000
01/09/02 GRAPPLER Personal 442 0.240 ND 5.000
01/05/02 LABORER Personal 88 0.000 ND 5.000
01/05/02 AREA SAMPLE Area 327 0.037 ND 5.000
01/04/02 LABORER Personal 310 0.500 ND 5.000
01/03/02 AREA SAMPLE Area 391 0.034 ND 5.000
12/27/01 Personal 297 0.077 ND 5.000
12/26/01 Personal 420 0.160 14.00 0.625
12/26/01 Personal 415 0.460 9.30 0.885
12/26/01 Area 415 0.720 10.00 0.833
12/22/01 GRAPPLER Personal 478 0.100 ND 5.000
12/22/01 GRAPPLER Personal 478 0.310 ND 5.000
12/22/01 GRAPPLER Personal 478 0.140 29.00 0.323
12/17/01 Area 310 0.082 ND 5.000
12/15/01 DRILLER Personal 298 0.200 ND 5.000
12/14/01 TORCH CUTTER Personal 230 2.300 1.40 2.941
12/14/01 TORCH CUTTER Personal 220 0.370 ND 5.000
12/11/01 Personal 254 0.220 14.00 0.625
12/11/01 Personal 273 0.220 22.00 0.417
12/11/01 Area 255 0.170 ND 5.000
12/09/01 Area 410 0.030 ND 5.000
12/09/01 Area 360 0.810 ND 5.000
12/08/01 AREA SAMPLE Area 285 4.500 4.80 1.471 YES
12/08/01 DRILLER Personal 285 2.200 3.80 1.724 YES
12/07/01 Area 373 0.480 ND 5.000
12/06/01 AREA SAMPLE Personal 316 0.028 ND 5.000
12/06/01 DRILLER Personal 325 0.110 25.00 0.370
12/06/01 DRILLER Personal 294 0.210 22.00 0.417
12/06/01 DRILLER Personal 354 0.130 ND 5.000
12/06/01 DRILLER Personal 325 0.071 37.00 0.256
12/05/01 DRILLER Personal 301 0.300 ND 5.000
12/05/01 AREA SAMPLE Area 290 0.053 ND 5.000
12/05/01 DRILLER Personal 299 0.120 ND 5.000
12/05/01 DRILLER Personal 298 0.230 23.00 0.400
12/01/01 DRILLER Personal 239 0.890 19.00 0.476 YES
12/01/01 DRILLER Personal 234 0.340 22.00 0.417
12/01/01 TORCHCUTTER Personal 460 0.062 ND 5.000
11/28/01 AREA SAMPLE Area 193 0.070 ND 5.000
11/28/01 AREA SAMPLE Area 341 0.047 ND 5.000
11/28/01 AREA SAMPLE Area 315 0.093 ND 5.000
11/24/01 AREA SAMPLE Area 330 0.076 49.00 0.196
11/23/01 AREA SAMPLE Area 327 0.480 ND 5.000
11/23/01 AREA SAMPLE Area 379 0.260 ND 5.000
11/23/01 CORER Personal 421 1.300 23.00 0.400 YES
11/23/01 CORER Personal 398 0.310 22.00 0.417
11/23/01 AREA SAMPLE Area 382 0.130 ND 5.000
11/23/01 AREA SAMPLE Area 350 0.240 ND 5.000
11/23/01 AREA SAMPLE Area 362 0.400 12.00 0.714
11/22/01 EXCAVATOR OPERATOR Personal 300 0.079 ND 5.000
11/22/01 Area 245 0.068 ND 5.000
11/22/01 LABORER Personal 293 0.050 ND 5.000
11/21/01 Area 260 0.094 ND 5.000
11/21/01 CORE DRILLER Personal 402 0.330 16.00 0.556
11/21/01 CORE DRILLER Personal 387 0.210 ND 5.000
11/21/01 Area 325 0.051 ND 5.000
11/21/01 Area 262 0.038 ND 5.000
11/20/01 Area 331 0.780 9.90 0.840
11/20/01 OPERATING ENGINEER Personal 73 0.580 ND 5.000
11/18/01 BORING MACHINE OPER Personal 400 0.038 48.00 0.200
11/18/01 AREA Area 350 0.077 ND 5.000
11/18/01 AREA Area 320 0.280 9.50 0.870
11/18/01 AREA Area 282 0.290 14.00 0.625
11/17/01 AREA SAMPLE Area 317 0.180 ND 5.000
11/16/01 AREA SAMPLE Area 198 0.066 ND 5.000
11/13/01 CONCRETE DRILLER Personal 140 0.130 ND 5.000
11/13/01 CONCRETE DRILLER Personal 182 5.700 14.00 0.625 YES
10/27/01 Area 369 0.057 ND 5.000
10/25/01 Area 282 0.058 ND 5.000
10/24/01 GRAPPLER OPERATOR Personal 275 1.000 ND 5.000
10/22/01 Area 365 0.310 ND 5.000
10/22/01 Area 390 0.250 ND 5.000
10/21/01 LABORER-CLEAN UP Personal 202 0.120 ND 5.000
10/21/01 LABORER Personal 79 0.140 ND 5.000
10/19/01 MACHINE OPERATOR, RUBBLE AND LOADING TRUCKS Personal 224 0.036 ND 5.000
10/19/01 IRONWORKER, RUBBLE SOUTH OF TOWER 2 AND NORTH OF 90 WEST. Personal 140 1.000 ND 5.000
10/19/01 Area 386 0.037 ND 5.000
10/19/01 Area 384 0.000 ND 5.000
10/18/01 EXCAVATOR OPERATOR Personal 360 0.300 ND 5.000
10/18/01 EXCAVATOR OPERATOR/OPERATOR ENGINEER Personal 362 0.710 ND 5.000
10/16/01 CARPENTER Personal 390 0.120 ND 5.000
10/16/01 OTHER RESCUER Personal 328 0.260 ND 5.000
10/14/01 GENERAL LABORER Personal 273 0.300 ND 5.000
10/12/01 Area 420 0.110 ND 5.000
10/10/01 Area 405 0.170 ND 5.000
10/10/01 BOBCAT OPERATOR Personal 385 0.830 ND 5.000
10/07/01 BOBCAT OPERATOR Personal 392 0.150 ND 5.000
10/05/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 155 0.240 ND 5.000
10/05/01 FRONT END LOADER Personal 223 0.000 ND 5.000
09/30/01 LABORER Personal 345 0.330 ND 5.000
09/29/01 Area 315 0.093 ND 5.000
09/25/01 GRAPPLER/CLAW OPERATOR/OPERATING ENGINEER Personal 162 0.000 ND 5.000
09/24/01 Area 240 0.110 ND 5.000
09/23/01 Area 239 0.220 18.00 0.500
09/22/01 EXCAVATOR OPERATOR/OPERATING ENGINEER Personal 125 0.000 ND 5.000
09/22/01 Area 376 0.054 ND 5.000