Table 17.
Recommended clearance exposure guidelines for transit passengers as well as various airport employees and personnel for selected CWAs and TICs in air and on surfaces (airborne for inhalation/ocular exposure; percutaneous vapor for protective clothing breach with full respiratory protection; and surface residual for “toddler” transit passenger SRCLs). For use during clearance decision-making following chemical terrorist release of selected CWA or TIC compounds under the LAX remediation protocol.
| Reasonable Maximum Re-entry Screening Guidelines (mg/m3) |
Alternative Re-entry Screening Guidelines (mg/m3) |
CWA Personnel Escape Guidelines (mg/m3) for 30-min percutaneous exposure | Transit Passenger SRCL4hr (mg/cm2 surface, calculated; 4 h continuous exposure duration) | Transit Passenger SRCL24hr (mg/cm2 surface, calculated; 24 h continuous exposure duration) | |
| CWA or TIC | <8-h duration exposurea | >8 but <24-h duration exposureb | |||
| Tabun (GA) | < 0.0010 | < 0.0003 | 11.1 | c | c |
| Sarin (GB) | < 0.0010 | < 0.0003 | 6.0 | c | c |
| Soman (GD) and Cyclosarin (GF) | < 0.00050 | < 0.0002 | 1.5 | c | c |
| VX | < 0.000071 | < 0.000024 | 0.13 | <1.85 × 10−3 | <3.08 × 10−4 |
| Sulfur mustard (H/HD) | < 0.008 | < 0.003 | 0.1 | <1.77 × 10−3 | <2.95 × 10−4 |
| Hydrogen cyanide (AC) | < 1.1 | <0.37 | d | c | C |
| Cyanogen chloride (CK) | <0.25 | <0.08 | d | c | c |
| Phosgene (CG) | <0.08 | <0.03 | d | c | c |
aEquivalent to the 8-h AEGL-1 for nerve agents and sulfur mustard (NRC/COT 2003), and hydrogen cyanide (NRC/COT 2002). Derivation of screening guidelines for phosgene and cyanogen chloride is described in this article.
bDerived by applying standard protocols and straight-line extrapolation from the 8-h AEGL-1 concentration (NRC/COT 2001). The same protocols were used to derive the alternative re-entry screening guidelines for phosgene and cyanogen chloride.
cBecause of the volatility of G-series nerve agents, HCN, phosgene, and cyanogen chloride, these volatile compounds are not considered persistent; there are thus insufficient data from which to estimate surface residues. If there is interest in surface sampling for these volatile compounds, the SRCL concentrations estimated for nerve agent VX can be employed. Doing so is a protective approach given the SRCL assumptions of VX persistence and toxicity, as well as the assumed frequency of child object mouthing behavior and dermal contact with surfaces.
dNot determined by NIOSH.