Worryingly, people can become allergic to the dangerous chemical at any time, even if they have been exposed to it before without problems.

Supertankers squeeze dangerous chemical cargoes through a city of more than 15 million people every week.

These guides have been developed to ensure worker safety when handling dangerous chemical toxins.

This eliminated the need to use osmium tetroxide, a rare, expensive, and dangerous chemical.

Some units have video systems and remote control in case of dangerous chemical fires.