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WTC OSHA Silica Sampling Data for Southeast 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?
06/21/02   Personal 450 0.560 6.10 1.235   
06/21/02   Area 470 0.900 7.10 1.099   
06/19/02   Area 493 0.520 4.30 1.587   
06/19/02   Area 480 0.050 ND 5.000   
06/19/02   Area 492 0.000 ND 5.000   
06/15/02   Area 413 0.140 ND 5.000   
06/15/02   Personal 373 6.200 3.40 1.852  YES 
06/12/02 LABORER  Personal 434 0.730 4.30 1.587   
06/12/02 DOCKBUILDER  Personal 421 0.220 12.00 0.714   
06/12/02 DOCKBUILDER  Personal 420 0.220 20.00 0.455   
06/10/02 DOCKBUILDER  Personal 399 0.150 ND 5.000   
06/10/02 DOCKBUILDER  Personal 396 0.210 ND 5.000   
06/10/02 DOCKBUILDER  Personal 408 0.710 6.80 1.136   
06/03/02   Area 190 0.240 ND 5.000   
06/03/02   Area 190 0.140 ND 5.000   
06/03/02   Area 200 0.120 ND 5.000   
06/03/02   Area 195 0.066 ND 5.000   
06/03/02   Area 283 0.300 12.00 0.714   
06/03/02   Personal 315 0.220 9.10 0.901   
06/02/02   Area 440 0.084 ND 5.000   
06/02/02   Area 445 0.250 6.50 1.176   
06/02/02   Area 440 0.150 ND 5.000   
06/02/02   Area 435 0.060 ND 5.000   
06/01/02   Area 420 0.000 ND   YES 
06/01/02   Area 430 0.047 ND 5.000   
05/31/02 DOCKBUILDER  Area 456 0.096 19.00 0.476   
05/31/02 DOCKBUILDER  Personal 440 0.240 34.00 0.278   
05/31/02 DOCKBUILDER  Personal 452 0.150 9.10 0.901   
05/31/02 DOCKBUILDER  Personal 438 0.150 10.00 0.833   
05/29/02 AREA SAMPLE  Area 455 0.043 ND 5.000   
05/29/02 DOCKBUILDER  Area 75 0.110 ND 5.000   
05/29/02 LABORER  Area 540 0.028 ND 5.000   
05/29/02 AREA SAMPLE  Area 530 0.052 ND 5.000   
05/29/02 LABORER  Area 515 0.120 14.00 0.625   
05/29/02 LABORER  Area 545 0.050 ND 5.000   
05/28/02 AREA SAMPLE  Area 306 0.048 ND 5.000   
05/28/02 AREA SAMPLE  Area 304 0.089 ND 5.000   
05/28/02 AREA SAMPLE  Area 301 0.100 ND 5.000   
05/26/02   Area 481 0.140 ND 5.000   
05/26/02   Area 460 0.130 ND 5.000   
05/26/02   Area 462 0.120 ND 5.000   
05/26/02   Area 410 0.094 ND 5.000   
05/26/02   Area 435 0.038 ND 5.000   
05/26/02   Area 410 0.067 ND 5.000   
05/26/02   Area 440 0.051 ND 5.000   
05/25/02   Personal 420 0.730 12.00 0.714  YES 
05/25/02   Area 445 0.100 ND 5.000   
05/25/02   Area 455 0.037 ND 5.000   
05/25/02   Area 450 0.032 ND 5.000   
05/25/02   Area 450 0.061 ND 5.000   
05/23/02   Area 483 0.045 40.00 0.238   
05/23/02   Area 473 0.079 ND 5.000   
05/23/02   Area 193 0.250 ND 0.591   
05/23/02   Area 318 0.250 16.00 0.591   
05/23/02   Area 483 0.043 ND 5.000   
05/23/02   Area 465 0.210 14.00 0.625   
05/23/02   Area 445 0.860 15.00 0.588  YES 
05/23/02   Area 465 0.140 ND 5.000   
05/23/02   Area 445 0.120 21.00 0.435   
05/23/02   Area 442 1.200 15.00 0.588  YES 
05/22/02   Area 465 0.095 18.00 0.500   
05/22/02   Personal 461 0.260 10.00 0.833   
05/22/02   Personal 447 0.410 11.00 0.769   
05/22/02   Area 446 0.630 8.00 1.000   
05/22/02   Area 445 1.500 8.00 1.000  YES 
05/22/02   Personal 439 0.410 13.00 0.667   
05/22/02   Area 440 0.480 17.00 0.526   
05/21/02   Area 400 0.310 14.00 0.625   
05/21/02   Personal 260 9.900 3.40 1.298  YES 
05/21/02   Personal 170 9.900 6.20 1.298  YES 
05/21/02   Personal 185 1.600 ND 2.188   
05/21/02   Personal 245 1.600 2.80 2.188   
05/20/02   Area 419 0.094 ND 5.000   
05/20/02   Area 419 0.061 ND 5.000   
05/20/02   Area 424 5.300 6.60 1.163  YES 
05/20/02   Personal 425 0.100 ND 5.000   
05/20/02   Personal 437 0.490 9.80 0.847   
05/17/02 BOBCAT  Area 430 0.650 7.90 1.010   
05/17/02   Personal 407 0.250 14.00 0.625   
05/17/02   Personal 405 0.360 7.70 1.031   
05/17/02   Personal 404 0.190 26.00 0.357   
05/17/02   Personal 410 0.380 9.90 0.840   
05/17/02   Personal 410 0.140 14.00 0.625   
05/15/02 DOCKBUILDER  Personal 420 0.720 9.60 0.862   
05/15/02 DOCKBUILDER  Personal 470 9.300 7.20 1.087  YES 
05/15/02 BOBCAT  Personal 305 0.088 ND 5.000   
05/15/02 BOBCAT  Personal 245 0.240 14.00 0.625   
05/15/02 GRAPPLER  Personal 403 0.073 31.00 0.303   
05/15/02 BOBCAT   Personal 403 0.120 ND 5.000   
05/15/02 AREA SAMPLE  Area 379 0.030 ND 5.000   
05/15/02 LABORER  Personal 377 0.000 ND 5.000   
05/14/02 AREA SAMPLE  Area 390 0.015 ND 5.000   
05/14/02 BOBCAT   Personal 393 0.029 ND 5.000   
05/14/02 BOBCAT  Personal 395 0.150 12.00 0.714   
05/14/02 AREA SAMPLE  Area 392 0.050 ND 5.000   
05/14/02 AREA SAMPLE  Area 383 0.025 ND 5.000   
05/14/02 BOBCAT  Personal 490 0.570 5.50 1.333   
05/14/02 BOBCAT  Personal 510 0.400 8.70 0.935   
05/14/02 DOCKBUIDER  Personal 470 0.470 10.00 0.833   
05/12/02 BOBCAT  Personal 325 0.078 ND 5.000   
05/12/02 LABORER  Personal 451 0.220 11.00 0.769   
05/12/02 DOCKBUILDER  Personal 421 0.680 8.90 0.917   
05/11/02 DOCKBUILDER  Personal 441 0.250 25.00 0.370   
05/11/02 DOCKBUILDER  Personal 440 0.031 ND 5.000   
05/11/02 AREA SAMPLE  Area 423 0.260 29.00 0.323   
05/11/02 AREA SAMPLE  Area 418 0.140 37.00 0.256   
05/11/02 DOCKBUILDER  Personal 341 0.140 14.00 0.625   
05/11/02 BOBCAT  Personal 458 0.093 16.00 0.556   
05/10/02 DOCKBUILDER  Personal 455 0.110 16.00 0.556   
05/10/02 AREA SAMPLE  Area 460 0.110 ND 5.000   
05/09/02   Personal 411 1.900 21.00 0.435  YES 
05/09/02 BOBCAT  Personal 474 0.700 14.00 0.625  YES 
05/09/02 DOCKBUILDER  Personal 466 0.240 ND 5.000   
05/09/02   Personal 207 1.500 10.00 0.833  YES 
05/09/02   Personal 182 0.160 27.00 0.345   
05/08/02   Personal 480 0.110 ND 5.000   
05/08/02   Personal 352 1.200 13.00 0.667  YES 
05/08/02   Personal 347 0.940 23.00 0.400  YES 
05/08/02   Personal 480 0.450 9.50 0.870   
05/07/02   Personal 269 0.073 ND 0.249   
05/07/02   Personal 206 0.073 55.00 0.249   
05/07/02   Personal 457 0.110 ND 5.000   
05/07/02   Personal 502 0.220 8.60 0.943   
05/07/02   Personal 492 0.110 ND 5.000   
05/07/02   Area 475 0.097 ND 5.000   
05/07/02   Personal 447 0.049 ND 5.000   
05/06/02   Personal 450 0.048 ND 5.000   
05/06/02   Personal 445 0.069 ND 5.000   
05/06/02   Personal 470 0.079 ND 5.000   
05/06/02   Personal 440 0.068 ND 5.000   
05/06/02   Personal 480 1.100 3.40 1.852   
05/05/02   Personal 380 0.034 ND 5.000   
05/04/02   Area 420 0.180 ND 5.000   
05/04/02   Area 420 0.190 ND 5.000   
05/04/02   Area 415 0.200 ND 5.000   
05/04/02   Area 420 0.120 ND 5.000   
05/03/02 DOCKBUILDER  Personal 80 0.470 16.00 0.556   
05/03/02 DOCKBUILDER  Personal 80 0.081 ND 5.000   
05/03/02   Personal 520 0.087 ND 5.000   
05/03/02   Personal 470 0.061 ND 5.000   
05/03/02   Personal 520 0.012 ND 5.000   
05/01/02   Personal 565 0.220 ND 5.000   
05/01/02   Personal 510 0.980 3.10 1.961   
05/01/02   Personal 497 0.280 ND 5.000   
05/01/02   Area 431 0.071 ND 5.000   
05/01/02   Personal 400 0.150 30.00 0.313   
05/01/02   Personal 450 0.032 ND 5.000   
04/30/02   Area 420 0.130 ND 5.000   
04/30/02   Personal 400 0.130 ND 5.000   
04/30/02   Personal 407 0.180 16.00 0.556   
04/30/02   Area 415 0.066 ND 5.000   
04/30/02   Personal 218 0.000 ND 5.000   
04/30/02   Personal 220 0.000 ND 5.000   
04/30/02   Personal 512 0.036 ND 5.000   
04/30/02   Personal 516 0.024 94.00 0.104   
04/30/02   Personal 503 0.018 ND 5.000   
04/29/02   Area 420 0.029 ND 5.000   
04/29/02   Personal 435 0.074 ND 5.000   
04/29/02   Area 420 0.000 ND 5.000   
04/22/02 AREA  Area 419 0.036 ND 5.000   
04/22/02 AREA SAMPLE  Area 415 0.200 26.00 0.357   
04/22/02 AREA SAMPLE  Area 422 0.032 ND 5.000   
04/22/02 AREA SAMPLE  Area 404 0.120 28.00 0.333   
04/22/02 AREA SAMPLE  Area 418 0.035 ND 5.000   
04/21/02 AREA SAMPLE  Area 497 3.400 18.00 0.500  YES 
04/18/02   Personal 451 0.096 ND 5.000   
04/15/02 AREA SAMPLE  Area 480 0.056 ND 5.000   
04/15/02 AREA SAMPLE  Area 475 0.030 ND 5.000   
04/15/02 AREA SAMPLE  Area 472 0.065 ND 5.000   
04/14/02   Area 465 0.038 ND 5.000   
04/14/02   Area 465 0.160 14.00 0.625   
04/13/02 NY FIRE DEPARTMENT  Personal 487 0.035 ND 5.000   
04/13/02 NY FIRE DEPARTMENT  Personal 474 0.000 ND 5.000   
04/13/02 NY FIRE DEPARTMENT  Personal 478 0.042 ND 5.000   
04/12/02 BOBCAT OPERATOR  Personal 452 0.580 3.70 1.754   
04/12/02 BOBCAT  Area 457 0.700 2.00 2.500   
04/12/02 DOCKBUILDER  Personal 510 0.130 ND 5.000   
04/12/02 LABORER  Personal 440 0.970 ND 5.000   
04/11/02   Personal 317 0.250 ND 5.000   
04/11/02   Personal 340 0.260 13.00 0.667   
04/11/02   Area 475 0.110 ND 5.000   
04/11/02   Area 448 0.240 18.00 0.500   
04/11/02   Personal 439 0.120 15.00 0.588   
04/11/02 AREA SAMPLE  Area 450 0.000 ND 5.000   
04/11/02 AREA SAMPLE  Area 430 0.000 ND 5.000   
04/11/02 AREA SAMPLE  Area 435 0.000 ND 5.000   
04/10/02 AREA SAMPLE  Area 525 0.070 ND 5.000   
04/10/02 AREA SAMPLE  Area 518 0.290 ND 5.000   
04/10/02 DOCKBUILDER  Personal 417 0.230 8.00 1.000   
04/10/02 DOCKBUILDER  Personal 414 0.900 12.00 0.714  YES 
04/10/02 AREA SAMPLE  Area 526 0.076 ND 5.000   
04/10/02   Area 385 0.052 ND 5.000   
04/10/02   Area 380 0.061 ND 5.000   
04/10/02   Area 396 0.170 ND 5.000   
04/10/02   Area 395 0.042 ND 5.000   
04/08/02   Personal 435 0.072 ND 5.000   
04/08/02   Personal 435 0.450 5.60 1.316   
04/08/02   Area 435 0.190 13.00 0.667   
04/08/02 AREA SAMPLE  Area 480 0.035 ND 5.000   
04/08/02 AREA SAMPLE  Area 491 0.048 ND 5.000   
04/08/02 AREA SAMPLE  Area 481 0.043 ND 5.000   
04/08/02 AREA SAMPLE  Personal 480 0.039 ND 5.000   
04/06/02 AREA SAMPLE  Area 385 0.130 13.00 0.667   
04/06/02 AREA SAMPLE  Area 405 0.000 ND 5.000   
04/05/02 AREA SAMPLE  Area 459 0.026 ND 5.000   
04/05/02 AREA SAMPLE  Area 453 0.000 ND 5.000   
04/04/02 NY FIRE DEPARTMENT  Personal 398 0.240 ND 5.000   
04/04/02 AREA SAMPLE  Area 390 0.092 ND 5.000   
04/03/02   Personal 429 0.140 ND 5.000   
04/02/02   Personal 410 0.180 ND 5.000   
04/02/02   Personal 408 0.270 ND 5.000   
04/02/02   Personal 482 0.120 ND 5.000   
04/02/02   Personal 483 0.210 ND 5.000   
04/02/02   Personal 455 0.066 ND 5.000   
04/02/02   Personal 452 0.190 ND 5.000   
04/01/02   Personal 445 0.830 3.20 1.923   
04/01/02   Personal 446 0.270 10.00 0.833   
04/01/02   Area 445 0.036 ND 5.000   
03/31/02   Personal 488 0.067 ND 5.000   
03/31/02   Personal 480 0.036 ND 5.000   
03/31/02   Personal 491 0.033 ND 5.000   
03/31/02   Personal 494 0.033 ND 5.000   
03/30/02   Area 435 0.055 ND 5.000   
03/30/02   Personal 438 0.310 11.00 0.769   
03/30/02   Personal 435 0.320 8.30 0.971   
03/30/02   Personal 424 0.650 11.00 0.769   
03/29/02 AREA SAMPLE  Area 120 0.420 14.00 0.625   
03/29/02 DOCKBUILDER  Personal 190 1.500 15.00 0.588  YES 
03/29/02 AREA SAMPLE  Area 120 0.068 ND 5.000   
03/29/02 DOCKBUILDER  Personal 190 0.340 11.00 0.769   
03/25/02   Area 419 0.085 51.00 0.189   
03/25/02   Personal 422 0.200 27.00 0.345   
03/25/02   Area 419 0.560 9.50 0.870   
03/24/02   Area 420 0.076 ND 5.000   
03/24/02   Area 435 0.110 ND 5.000   
03/24/02   Area 365 0.530 6.20 1.220   
03/24/02   Area 420 0.130 ND 5.000   
03/24/02   Area 240 0.240 16.00 0.556   
03/24/02   Personal 420 0.160 10.00 0.833   
03/24/02   Personal 420 0.220 13.00 0.667   
03/23/02 AREA SAMPLE  Personal 420 0.077 ND 5.000   
03/23/02 AREA SAMPLE  Personal 209 0.062 53.00 0.182   
03/23/02 AREA SAMPLE  Personal 424 0.036 ND 5.000   
03/23/02 DOCKBUILDER  Personal 404 0.085 ND 5.000   
03/23/02 DOCKBUILDER  Personal 399 0.210 21.00 0.435   
03/22/02 GRAPPLER  Personal 419 0.150 ND 5.000   
03/22/02 BOBCAT  Personal 424 0.250 ND 5.000   
03/22/02 DOCKBUILDER  Personal 407 2.700 21.00 0.435  YES 
03/22/02 DOCKBUILDER  Personal 413 0.220 8.10 0.990   
03/22/02 DOCKBUILDER  Personal 402 0.290 25.00 0.370   
03/22/02 DOCKBUILDER  Personal 421 0.440 16.00 0.556   
03/22/02 DOCKBUILDER  Personal 416 0.160 17.00 0.526   
03/21/02   Personal 405 0.330 18.00 0.500   
03/21/02   Personal 411 0.260 21.00 0.435   
03/21/02 AREA SAMPLE  Area 540 0.320 18.00 0.500   
03/21/02 EXCAVATOR  Personal 540 0.230 ND 5.000   
03/21/02 DOCKBUILDER  Personal 510 0.330 21.00 0.435   
03/21/02 GRAPPLER  Personal 540 0.022 ND 5.000   
03/21/02 GRAPPLER  Personal 540 0.092 ND 5.000   
03/20/02   Personal 315 0.200 22.00 0.417   
03/20/02   Personal 387 0.130 ND 5.000   
03/20/02   Area 387 0.490 ND 5.000   
03/20/02   Area 385 0.200 ND 5.000   
03/20/02   Area 381 0.079 ND 5.000   
03/20/02   Area 129 0.000 ND 5.000   
03/20/02   Personal 314 0.820 21.00 0.435  YES 
03/20/02   Personal 316 0.400 20.00 0.455   
03/19/02   Personal 426 0.440 19.00 0.476   
03/19/02   Personal 425 0.450 13.00 0.667   
03/19/02   Personal 425 1.900 3.20 1.923   
03/19/02   Personal 424 1.100 6.30 1.205   
03/19/02   Personal 444 0.025 ND 5.000   
03/19/02   Personal 430 0.069 ND 5.000   
03/18/02   Personal 420 1.400 12.00 0.714  YES 
03/18/02   Personal 417 0.400 25.00 0.370  YES 
03/18/02   Personal 413 0.910 42.00 0.227  YES 
03/18/02   Personal 409 1.100 20.00 0.455  YES 
03/17/02   Personal 413 0.150 ND 5.000   
03/17/02   Personal 419 6.900 ND 5.000  YES 
03/17/02   Personal 425 0.047 ND 5.000   
03/17/02   Personal 428 0.095 22.00 0.417   
03/17/02   Personal 403 0.630 2.90 2.041   
03/17/02   Personal 420 0.150 ND 5.000   
03/16/02 BOBCAT  Personal 393 0.220 ND 5.000   
03/16/02 AREA SAMPLE  Area 369 0.120 ND 5.000   
03/16/02 GRAPPLER  Personal 396 0.310 ND 5.000   
03/16/02   Area 470 0.031 ND 5.000   
03/16/02   Area 470 0.031 ND 5.000   
03/15/02 GRAPPLER  Area 430 0.420 ND 5.000   
03/15/02 AREA SAMPLE  Area 424 0.810 9.30 0.885   
03/13/02 AREA SAMPLE  Area 445 0.085 ND 5.000   
03/13/02 AREA SAMPLE  Personal 455 0.120 ND 5.000   
03/11/02   Personal 460 0.073 ND 5.000   
03/11/02   Personal 455 0.058 ND 5.000   
03/11/02   Personal 455 0.000 ND 5.000   
03/09/02 GRAPPLER  Area 438 0.044 ND 5.000   
03/09/02 AREA SAMPLE  Area 435 0.035 ND 5.000   
03/09/02 AREA SAMPLE  Area 420 0.039 ND 5.000   
03/09/02 AREA SAMPLE  Area 420 0.110 ND 5.000   
03/09/02 AREA SAMPLE  Area 420 0.035 ND 5.000   
03/09/02 AREA SAMPLE  Area 420 0.036 ND 5.000   
03/08/02 NY FIRE DEPARTMENT  Personal 478 0.087 ND 5.000   
03/08/02 AREA SAMPLE  Area 404 0.062 ND 5.000   
03/08/02 DOCKBUILDER  Personal 406 0.067 ND 5.000   
03/08/02 DOCKBUILDER  Personal 423 0.088 ND 5.000