On 18 December 2025, the Official Gazette of the Canary Islands in Spain published Decree 185/2025 of 10 December, on the protection of the atmosphere of the Canary Islands. This Decree introduced for the first time in Spain odour limit values at a regional level.

   The Decree 185/2025 of 10 December, on the protection of the atmosphere of the Canary Islands introduces a new regulation on odour pollution, classifying odour-generating activities into three levels with the following odour ambient air target values: 3, 6 and 9 ou_E/m³, measured according to the UNE EN 13725 standard.

   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   The H4 document (now withdrawn) used to provide extensive technical guidance, including benchmarked odour assessment approaches, structured testing and recommended modelling practice.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 Sixteen years later the Agency has concluded that the H4 format was out of date and replaced it with a new online guidance which is shorter (no pdf here) and more principle‑based.