Regulation 23 Average exposure indicator
The Secretary of State must calculate the average exposure indicator for PM2.5 (“AEI”) for the United Kingdom for 2010, 2015 and 2020.
The AEI must be calculated as follows—
an average annual measurement must be derived from measurements at all the sampling points in urban background locations which have been installed in accordance with Section B of Annex V to Directive 2008/50/EC;
the average annual measurement in paragraph (a) must be averaged over three calendar years.
The AEI for 2010 must be based on measurements for the years 2009, 2010 and 2011.
The AEI for 2015 must be based on measurements for the years 2013, 2014 and 2015.
The AEI for 2020 must be based on measurements for the years 2018, 2019 and 2020.
The Secretary of State must ensure that the distribution and number of sampling points used for calculating the AEI adequately reflects the exposure of the general population.