Department of Labor Seal photos representing the workforce - digital imagery© copyright 2001 photodisc, inc.
Department of Labor Seal www.osha.gov   [skip navigational links] Search    Advanced Search | A-Z Index
   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   
 
Back to Top Back to Top www.osha.gov www.dol.gov
Contact Us | Freedom of Information Act | Information Quality | Customer Survey
Privacy and Security Statement | Disclaimers
Occupational Safety & Health Administration
200 Constitution Avenue, NW
Washington, DC 20210