Background: Mercury and its compounds are priority toxic substances. Ireland reports mercury emissions to atmosphere as a party to the UN Convention on Long Range Transboundary Air Pollution using conversion factors based on economic activity (Environmental Protection Agency, 2021a). The conversion factors are no longer relevant to current waste management practices. The Minamata Convention and preceding EU Directives on Eco-Design have reduced the mercury content of products. However, an environmental threat remains in the case of historic equipment and exempted product categories. Aim: This paper scopes and ranks key categories of mercury-added products (MAPs) in the Irish built environment. Methodology: Put on market, waste collected, waste characterisation and data on MAPs in scrap metal collection were analysed. The rate of mercury lost per annum based on these data was calculated. The UN Mercury Inventory Toolkit was employed to identify additional MAPs and grey data were reviewed to scope and priority rank MAPs in the Irish built environment. Findings: Upwards of 18kg of mercury was lost to the environment due to leakage of waste electronics and mercury containing lamps from home maintenance and renovation to general and scrap metal waste streams. The quantity of MAP lighting in building stock is greatly underestimated. Professional lighting installation as part of governmental energy efficiency retrofits caused a stock increase that may not fully be reflected in the put-on-market data available to policy makers. Conclusions & Implications: Contamination of materials prior to treatment needs consideration to realise elements of the circular economy. Exempted MAP stocks in the built environment are currently unknown. Empirical studies are required to quantify these and target safe handling. This work was supported in part through the financial support of Science Foundation Ireland under Grant number 21/PATH-S/9313.