Air pollution and climate change are often treated as if they were two separate problems, when they actually represent the same scourge. While the former has the most acute impact on human health, and causes economic harm to buildings, vegetation and activities such as tourism, the latter affects lives, property and the natural world in a less direct way, through weather disasters, windstroms, floods, droughts and rising sea levels. -- But emission sources for air pollutants and the greenhouse gases coincide, and there is great benefit in simultaneously cutting emissions of air pollutants and greenhouse gases. A combined strategy reduces the cost of counteracting both these threats to human and wellbeing of society.