Cleaning people that have been exposed to chemical or biological agents.

The air in and around the stadium is also being constantly monitored to make sure it has not been contaminated by chemical or biological agents.

Resources listed in this guide cover the history, nature, toxicity, and physical effects of chemical and biological agents.

Moreover, on the vital matter of chemical and biological agents, the agencies' overall assessments were entirely reasonable.

Authorities also found books relating to the production of chemical and biological agents.

This depends on the chemical or biological agent used.

But several officials were concerned about the possibility of a chemical or biological agent being dispersed inside a subway car.

But they have not found traces of chemical or biological agents that could be used as weapons, officials acknowledged.

Was it low levels of exposure to chemical or biological agents?