# The Air Quality (Ozone) (Wales) Regulations 2003, Part I: Definitions and interpretation


When assessing compliance with the target values and long-term objectives set out in this Schedule—
(a) all values must be expressed in μg/m3;
(b) the volume must be standardised at the following conditions of temperature and pressure: 293K and 101.3kPa;
(c) the time must be specified in Central European Time;
(d) “AOT40” (expressed in (μg/m3)·hours) means the sum of the difference between hourly concentrations greater than 80μg/m3 (which equals 40 parts per billion) and 80μg/m3 over a given period using only the 1 hour values measured between 8:00 and 20:00 Central European Time each day;
(e) in order to be valid, the annual data on exceedances must meet the criteria set out in Part II of Schedule 8.

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Source: https://www.legislation.gov.uk/wsi/2003/1848/schedule/1/part/I (the official version)
Page: https://openlegislation.uk/air-quality-ozone-wales-regulations-2003/schedule-1/part-I
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.