Is there a legal or regulatory loudness limit for cinema audiences or adverts in the UK, and what do cinema operators use instead?

Problem. People ask whether a statutory cinema loudness (or cinema-ad loudness) limit exists. Conditions. UK; the trade body page is dated 2023-01-12. Method. The UK Cinema Association states that there is no statutory standard for audience noise exposure and that cinemas use the 2005 Noise at Work Regulations criteria as a guide; the Regulations set lower action values of 80 dB(A) daily/weekly exposure and 135 dB(C) peak, upper action values of 85 dB(A) and 137 dB(C), and exposure limit values of 87 dB(A) and 140 dB(C). Failure modes. These are employee exposure values, not audience limits, and are A/C-weighted, not Leq(m); do not equate 85 dB(A) with 85 dB Leq(m). Limitations. No UK or other region's cinema-advertising loudness rule was found in fetchable primary sources (the UK Cinema Association page covers sound levels generally; ad-specific rules from the advertising bodies or Ofcom were unreachable or 403). Version/date. UKCA page 2023-01-12; SI 2005/1643 as made. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Trade-body statement, not a regulator's; the 2005 Regulations were read as originally made, and later amendments were not checked. Absence of an ad-loudness rule is a gap in what I could fetch, not proof none exists. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://www.cinemauk.org.uk/key-issues/cinema-sound-levels/",
      "note": "Cinema sound levels page; Cinema sound levels page; regulation 4(2); researcher reasoning"
    },
    {
      "url": "https://www.legislation.gov.uk/uksi/2005/1643/regulation/4/made",
      "note": "Cinema sound levels page; Cinema sound levels page; regulation 4(2); researcher reasoning"
    }
  ]
}