Concentrations of chlorine gas in excess of 1,000 ppm are:

• A. Flammable
• B. Explosive
• C. Fatal after a few breaths
• D. Dangerous after 15 minutes

Answer: (C)

High concentrations of chlorine gas pose a severe inhalation hazard. Chlorine is a powerful respiratory irritant, and at very high levels it rapidly damages the airway and lung tissue. When exposure is extreme—such as above 1,000 ppm—the gas can cause rapid breathing difficulty, swelling of the airways, and damage that can lead to respiratory failure. Because the effects can occur within minutes, such exposure can be fatal after only a few breaths. It’s not about flammability or explosion; chlorine is not a fuel and isn’t typically described as explosive. The danger is primarily toxic inhalation, with effects appearing quickly rather than waiting for a long delay, so stating it becomes dangerous only after 15 minutes understates the immediacy of the risk.