The third approach is the banding system, which is more popular in European countries like the UK and France (websites 3, 13). The main deviation is that instead of using an index scale of 0 to 500, a scale of 0 to 10 is being used. For the UK system, this index scale of 10 is further broken down into four bands of ‘low’ (1-3), ‘moderate’ (4-6), ‘high’ (7-9) and ‘very high’ (10) (website 13). The key reference point for this banding system is the breakpoint value between the ‘low’ and ‘moderate’ bands. The lower bound of index value 4 is set to correspond to the UK Air Quality Standards for all pollutants but NO 3 2. In this case, the 1-hour national standard for NO2 is 200 g/m , whereas the lower bound of index value 4 for NO2 is 287 g/m3 (website 13).
A Study of the Air Pollution Index Reporting System by Prof. Wong Tze Wai School of Public Health and Primary Care The Chinese University of Hong Kong