As flames and smoke from burning bushes billowed toward them, Catalan firefighters calmly controlled the progress of a planned fire on a forested hillside — an exercise aimed at reducing the danger of blazes breaking out later in the summer heat.
Prescribed forest burns like this, which thin out flammable undergrowth, are a well-known way of lowering wildfire risks, which are rising as the Earth's climate heats up.
Less understood is the impact on the health of the people who work to prevent and battle those forest fires.