Jason must evacuate the premises, (himself and all people nearby).
Not all chemicals are odorous, some are odorless and even colorless such as carbon monoxide or even radon.
The train may contain radon. Radon is an alpha emitter.
In high doses, it is carcinogenic in exposed populations, with an excess mortality due to lung cancer that increases linearly with the cumulative exposure of the lung to radon and its descendants.
