(18)Appendix C to Annexes I and II to Delegated Regulation (EU) 2021/2139 (‘Appendix C’) lays down generic technical screening criteria for ‘do no significant harm’ to pollution prevention and control applicable to different activities. That Appendix specifies criteria for the use and presence of chemicals. So far, it has provided for exemptions in certain cases, where the use of those chemicals has been proven to be essential to the society. That exemption poses certain concerns in terms of legal certainty and verification for undertakings and financial market participants, linked to the absence of clear definition of the concept of ‘essential use’. Therefore, pending further guidance clarifying how operators should assess and document that they comply with the upcoming Commission’s horizontal principles on essential use of chemicals, targeted changes should be made to that Appendix and the concept of ‘use essential for the society’ should be replaced by criteria that offer more legal certainty and for which compliance can be verified more easily. Pending that further guidance, the concept of ‘use essential for the society’ should thus be replaced by the requirement that no other suitable alternative substances or technologies are available on the market, and that the substances are used under controlled conditions.