Images from a homeland security experiment

Department of Homeland Security officials recently simulated the release of airborne contaminants in Boston's subway system, known locally as the 'T.' The exercise aimed to gauge how the air flows in order to be ready in the event of a real security incident.

Public explanation

A scientist with a team of investigators for the Department of Homeland Security explains how a simulated chemical attack will take place throughout the subway system in Boston as part of a test on airflow.

Through the tunnels

The team is investigating how chemical or biological contaminants released into the air would travel through the subway system's underground tunnel network.

Securing riders

Understanding how substances travel through the subway's five lines will help the MBTA Transit Police fine tune evacuation plans to protect the subway's more than 1.3 million daily riders

Gas monitors

About 40 gas samplers and more than 25 particle counters placed throughout the underground system monitored the concentration of the tracer gases and particles.

Weather effects

Equipment measures how hot, humid summer weather impacts the movement of airborne material. Tests were also conducted in winter to gauge temperature, humidity and other weather factors.

Analyzing contaminant travel

Monitoring and tracking equipment analyzes gas and concentrations, giving scientists an idea of how the chemicals travel and how quickly they disperse.

New plans may save lives

Data will be shared with first responders who can use them in devising evacuation plans for riders, as well as to adjust ventilation, and modify train movements after an attack or accidental release.

Recommended
Join the discussion
Be the first to comment on this article. Our Commenting Policies