Toxic chemicals that pollute groundwater are formed up in the stratosphere, surprise findings show

The view of Earth's atmosphere from inside the cockpit of NASA’s WB57 research aircraft.

A toxic chemical that pollutes groundwater originates high in Earth's atmosphere, a scientific flight has revealed.

Perchlorates, a group of chlorine-containing chemicals that can disrupt thyroid function, form on particles of smoke and organic material in the stratosphere, between 6 and 31 miles (10 to 50 kilometers) above the planet's surface, according to a new study.