Our focus is the cumulative influence of biomass burning (BB) on PM_2.5 concentrations in a country far-removed from major BB sources. We find that ~10% of UK annual mean PM_2.5 is conditional on BB emissions, 97% and 73% from BB outside the UK and outside Europe. The majority of the long-range component is secondary, of which much of the inorganic is mediated through local anthropogenic emissions. The relative contribution of BB in such locations is an increasing challenge for PM_2.5 targets.