The Use of Quantitative Health Risk Analysis in Risk Management

The use of Quantitative Health Risk Analysis in Risk Management

Quantitative Risk Analysis (QRA) is largely used to estimate Individual Risk and Societal Risk related to the accidental release of toxic or inflammable substances. This type of assessment takes into account the short duration of accidental releases, usually involving large amounts of materials, and the (low) probabilities of the scenarios.

There are situations involving the release of toxic materials that are not covered by a conventional QRA. Continuous release of toxic materials are associated with fugitive emissions and operating losses from process equipments, valves, lines and connectors. Another approach (Health Risk Analysis - HRA or Quantitative Health Risk Analysis - QHRA) is required to take into account the high frequency of those releases to estimate the probability of impacting human health, especially for long term exposure of populations.

While the occupational health of workers is closely controlled by the industry and the government authorities following well established monitoring procedures and protocols, the health risks posed by process plants emissions to the populations need to be quantified so that proper control measures – usually requiring changes in process and equipments - can be identified and implemented.

A QHRA should answer questions like: Could exposure to a specific chemical cause significant health problems? How much of the chemical would someone have to be exposed to before it would be dangerous? How serious could the health risks be?

The aim of this paper - based on a real case - is to call the attention to the need of considering the control of acute and chronic health risks in Risk Management Programs. It covers and discusses all the steps involved in a QHRA, including the emissions inventory, dispersion analysis and quantification of health risks.