Assessing the application of acute toxic gas standards

In this paper, we compare acute toxic gas standards developed for occupational, military, and civilian use that predict or establish guidelines for limiting exposure to inhaled toxic gases.

Large disparities between guidelines exist for similar exposure scenarios, raising questions about why differences exist, as well as the applicability of each standard. The motivation and rationale behind the development of the standards is explored with emphasis on the experimental data used to set the standards.

The Toxic Gas Assessment Software (TGAS) is used to quantitatively compare current acute exposure standards, such as: Acute Exposure Guidelines (AEGL), Immediate Danger to Life or Health (IDLH), Purser, International Organization for Standardization (ISO 13571), and Federal Aviation Administration (FAA). The TGAS software does this by calculating the body-mass-normalized internal doses of each gas exposure in each standard, which is then plotted on a cumulative distribution function for a normal or susceptible population to visualize the relationship of the standards to each other. To focus the comparison, acute toxic gas standards for five common fire gases, carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen chloride (HCl), nitrogen dioxide (NO₂), and acrolein (C₃H₄O), are explored.

It was found that differences between standards can be reconciled when the target population, effect endpoint, and incidence level are taken into account.

By analyzing the standards with respect to these factors, we can acquire a better understanding of the applicability of each.