Household air pollution, much of it due to a lack of electricity, causes an additional 4.3 million deaths. Roughly half this pollution can be attributed to outdoor air pollution. This corresponds to an estimated loss in welfare in OECD countries that is far above one trillion USD, corresponding to roughly 3% of GDP (OECD, 2014). While the range of uncertainty over impacts and their monetised values remains considerable, methodologies are now firmly established and ranges of reasonable values exist.