Annual technical reports for the Polycyclic Aromatic Hydrocarbons (PAH) Monitoring Network, part of the UK's air pollution monitoring regime.
Source
https://www.gov.uk/government/publications/polycyclic-aromatic-hydrocarbons-pah-monitoring-network-technical-reportsCanonical document at the regulator. Always cite this URL — not the Vantage detail page — in compliance evidence.