# The Environmental Protection (Prescribed Processes and Substances) Regulations 1991, 

Extent: E+W+S

(a) Odorising natural gas or liquified petroleum gas, except where that process is related to a Part A process.
(b) Blending odorant for use with natural gas or liquified petroleum gas.
(c) Any process for refining natural gas not falling within paragraph (aa) of Part A of this Section.

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Source: https://www.legislation.gov.uk/uksi/1991/472/schedule/1/part/1/crossheading/section-11-gasification-and-associated-processes-nil (the official version)
Page: https://openlegislation.uk/environmental-protection-prescribed-processes-and-substances-regulations-1991/schedule-1/part-1/crossheading-section-11-gasification-and-associated-processes-nil
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.