Every rush hour, bumper-to-bumper traffic belches out diesel fumes along Madrid's Gran Via, a six-lane artery that bisects the Spanish capital. Art Deco facades line the grand boulevard.
But they're blackened with soot.
"The pollution hurts my eyes, and I can feel it in my throat," says commuter María Villallega, 48, who lives in the city center and walks to work. "I don't own a car myself, and I'll be happy when they're not allowed here anymore. We need to protect the planet, and ourselves."