Air conditioning, which mechanically cools indoor air, can be installed in a single room or building. Air conditioning strongly protects against adverse health impacts during extreme heat, and is on track to be the leading intervention against extreme heat globally. Air conditioning can be implemented quickly, over hours to days depending on the type of installation. Implementation costs from several hundred dollars for a window unit up to several thousand for air conditioning an entire home. While strongly protective, air conditioning is costly to install and operate and is not equitably distributed; its use can also contribute to air pollution and carbon pollution. Multiple more sustainable, albeit less effective, cooling strategies are available, and strategies for subsidizing installation and operating costs can decrease inequities in air conditioning distribution and utilization.