# The Air Quality (Ozone) (Wales) Regulations 2003, Paragraph 1


The flow around the inlet sampling probe should be unrestricted (free in an arc of at least 2700) without any obstructions affecting the air flow in the vicinity of the sampler, i.e. away from buildings, balconies, trees and other obstacles by more than twice the height the obstacle protrudes above the sampler.

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Source: https://www.legislation.gov.uk/wsi/2003/1848/schedule/2/paragraph/1 (the official version)
Page: https://openlegislation.uk/air-quality-ozone-wales-regulations-2003/schedule-2/paragraph-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.