Table 2.
Maximum estimated concentrations of BTEX compounds and light aliphatics directly over the Exxon Valdez oil spill compared to recommended human exposure limits.
| NIOSHb REL (ppm) |
||||
|---|---|---|---|---|
| Compound | Hour of spill with maximum concentrationa | Maximum concentrationa (ppm) | TWA | STEL or C |
| Benzene | 1 | 4.86 | 0.1 | 1 |
| Toluene | 1 | 8.24 | 100 | 150 |
| Ethylbenzene | 1 | 0.83 | 100 | 125 |
| Xylenes | 3 | 2.65 | 100 | 150 |
| Hexane | 1 | 1.29 | 100 | 510 |
| Heptane | 1 | 4.36 | 85 | 440 |
| Octane | 1 | 4.04 | 75 | 385 |
| Nonane | 3 | 2.01 | 200 | — |
| TOTAL | NA | 28.28 | NA | NA |
aValues from Hanna and Drivas (1993); hour refers to time after start of the spill; bNIOSH = National Institute for Occupational Safety and Health, REL = recommended exposure limits; TWA = time-weighted average; STEL = short-term exposure limits; C = ceiling REL, not to be exceeded at any time (NIOSH 2007).