Figure 19.1: Days when air pollution is moderate or higher: by site, 2010 to 2014 (1)
Source: Environment, Food and Rural Affairs
Not every site in the automatic monitoring network is included. Sites must also meet certain data capture targets to be used in the index. Urban sites are required to monitor PM10 and rural sites are required to monitor ozone. For the required pollutants it should be more than or equal to 75% of the year. For ozone this applies to both the full year and the summer period in isolation.