The UK Environment Agency has replaced its long‑standing H4 odour guidance last updated in 2009 with a new GOV.UK guidance hub titled “Odour management: comply with your environmental permit,” a change that removes many of H4’s previously detailed technical prescriptions and moves regulation toward demonstrating compliance with best available techniques (BAT) and appropriate measures. In addition, the odour limits are gone. 

   The H4 document (now withdrawn) used to provide extensive technical guidance, including benchmarked odour assessment approaches, structured testing and recommended modelling practice. The first H4 Horizontal Guidance for Odour was published in 2002 and included the first odour limits set in the UK. In 2009 this Guidance was updated but the odour limits based on percentiles 98 were left untouched. Sixteen years later the Agency has concluded that the H4 format was out of date and replaced it with a new online guidance which is shorter (no pdf here) and more principle‑based.

   The kick-off meeting for drawing up the Best Available Techniques REFerence document for Landfills (LAN BREF) took place as a hybrid event from 6 to 9 October 2025, gathering 166 experts—82 in person and 84 online—representing EU Member States, Norway, industry, environmental NGOs, the European Chemicals Agency (ECHA), and European Commission services. This meeting launched the process of developing a standalone BAT reference document specifically for landfills, reflecting their importance and complexity within waste management.

   On 17 August 2025, the European Commission published the Decision establishing the BAT conclusions for Waste Treatment (WT) in the Official Journal of the EU. This BREF focuses on waste treatment technologies but intentionally left landfills out of its scope. The decision to exclude landfills was made deliberately to allow for a dedicated and more comprehensive BAT document addressing landfill-specific issues, which is now being developed through the ongoing LAN BREF process.