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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   
 
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