Table 3. Data source and the assumptions used for environmental exposure calculations.

NO.	Policy ID	Sources	Assumptions
1	E-transport system	NA	No additional data requirements.
2	Active travel	London Travel Demand Survey ( TFL, 2018), ( BEIS, 2012)	As with GHG emissions, the London Travel Demand Survey is used to establish the current proportion of passenger kms travelled by various modes. Transport emission factors for various pollutants per km were obtained from the National Atmospheric Emissions Inventory ( BEIS, 2012).
3	Building upgraded	Hamilton et al., 2015; Taylor et al., 2018	Predictions for changes in indoor environmental exposures due to home energy efficiency retrofit were taken from Hamilton et al., 2015. This includes indoor and outdoor PM 2.5, Radon, mould and standard indoor temperature. Predicted changes in overheating were based on work by Taylor et al. (2018).
4	Heat pumps	NA	No additional data requirements. Heat pumps assumed to completely eliminate direct emissions of pollutants from homes.
5	Heat networks	NA	No additional data requirements. Heat networks assumed to eliminate direct emissions of pollutants.
6	PV installation	DEFRA, 2019	Emissions due to power generation were determined from DEFRA (2019). This was multiplied by the reduction in demand due to the adding solar PV.
7	Grid decarbonisation	DEFRA, 2019	Emissions due to power generation were determined from DEFRA (2019). It is assumed grid decarbonisation would eliminate the majority of these emissions.
8	Green gas supply	NA	No data currently available.
9	Greenspace	GLA, 2015	Proportion of pollution removed by the urban forest was obtained from Valuing London's Urban Forest ( GLA, 2015).
10	Zero waste city	NA	No data currently available.