他们靠燃烧树枝和牛粪来做饭取暖，由此造成的室内空气污染每年导致350万人死亡 — — 这才是世界范围内最迫在眉睫的环境问题。
They cook and keep warm by burning twigs and dung, producing indoor air pollution that causes 3.5 million deaths per year – by far the world’s biggest environmental problem.