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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 |