Location choice of Air quality monitors in China

Since 2013, China has added more than four thousand air quality monitoring stations that provide the public with real-time information on six airborne pollutants, i.e., particulate matter (PM) 2.5, PM10, sulfur dioxide, nitrogen dioxide, ozone, and carbon monoxide. Authorities manage these monitors at four levels of the government: state, provincial, municipal, and county. Typically, pollution monitors are located where they could be deemed useful, for example, within more air-polluted areas or near schools, hospitals, road traffic, and industries. While the real-time information has helped individuals, firms, and governments make decisions; it is unclear how a government body makes siting decisions. This paper aims to answer three questions: Where are the pollution monitors located? What drives the decision to add a new monitor in a particular location? Is there a difference in location choice behavior between central and local governments in China? We find that, in 2021, central monitors were located in cleaner areas than local monitors, and both monitors were located around public buildings like hospitals. However, when it comes to new placements, both monitors are generally positioned in more polluted areas, with local monitors more likely to be placed in the "dirtiest" locations. We also find that central and local monitors are both clustered around each other.