A man who scavenges recyclable materials for a living walks across a mountain of garage amidst smoke from burning trash at Dandora, the largest garbage dump in the capital Nairobi, Kenya Tuesday, Sept. 7, 2021. Tuesday marks the second "International Day of Clean Air for blue skies" aimed at rallying countries to recognise and combat the environmental risk to human health posed by air pollution, according to the United Nations. (AP Photo/Brian Inganga)