Regulation and reformulation: how the EU Paints Directive shaped volatile organic compound emissions from UK decorative paints

Decorative paints have undergone substantial solvent reformulation in response to air quality regulatory pressure and advances in materials science, but they remain an important contributor to national VOC emissions. Paint-derived VOCs currently represent 9.6% of total United Kingdom VOC emissions. The changes in UK emissions from decorative paints (1990–2024) have been quantified using a combination of national emissions inventory data, laboratory analysis using headspace GC/MS, and atmospheric modelling. A major decline in total mass of VOC emissions from paints followed the implementation of the EU Paints Directive, with per capita emissions falling by approximately 60% between 2004 and 2019 from 0.532 kg per person per year to 0.210 kg per person per year. The reduction in mass of paint VOC emissions coincided with a transition away from hydrocarbon solvents, notably alkanes such as decane, and other alkane isomers in the C8–C12 range. Paints in 2024 contain virtually no alkane content, instead comprising a wide range of chemical functionalities, including alcohols, ketones, esters, and siloxanes. The VOC speciation in 2024 varied significantly by manufacturer, but rather little across manufacturers' product range for different end-uses. Reformulated 2024 paints exhibited substantially lower SOA formation potential, approximately six times lower than older alkane-based paint formulations and had reduced total hydroxyl radical reactivity. Atmospheric model simulations comparing decane (reflective of 1990 paints) and t-butanol (reflecting 2024 paints) indicated that modern VOC emission mixtures likely degrade more slowly and generate less formaldehyde as a by-product. This study provides an updated VOC speciation for paints, suitable for use in emissions inventories and air pollution assessments.