10 © Centre for Economics and Business Research The annualised revenue from those users continuing to use non ULEZ compliant vehicles is £169 million. The assessed cost to those who change their behaviour in response to the charge is about half that at £84 million. This gives a total direct negative economic effect of £253 million per annum. 3.6. Indirect economic effects There are indirect effects from the private journeys that are suppressed or shifted by mode or by type of vehicle as a result of ULEZ. But we argue that the direct estimates incorporate them. For business journeys or activities that do not take place, the economics is less clear. A tradesperson who decides not to undertake a piece of work because of ULEZ is making a calculation based on his or her loss of profit; but the loss of activity includes the entire value added that is lost. But in many cases the type of business where activity is lost is small and may well be proprietor owned. It is probably not unreasonable therefore to assume that the direct cost of ULEZ to the proprietor is not very different from the total cost to the economy. 3.7. Total economic effects The total economic impact is the deadweight cost to the consumer plus the revenue cost to the consumer minus the revenue earned by TfL/GLA (in other words the revenue drops out – it is in economics terms a transfer from one party to another) plus the admin costs. This is £84 million (from 3.5) plus £115 million (from 3.4), which equals £199 million. 3.8. Air quality impact The House of Commons briefing on the proposed expansion quotes the most comprehensive independent study by Imperial College6: In a study published in the journal, Environmental Letters, in 2021, researchers from Imperial College London used publicly available air quality data to measure changes in pollution in the twelve-week period from 25 February 2019, before the ULEZ was introduced, to 20 May 2019, after it had been implemented7. They attempted to control for the effects of weather variations, and then used statistical analysis to look for and quantify changes in pollution. They concluded that the ULEZ had “caused only small improvements in air quality in the context of a longer-term downward trend in London's air pollution levels.” The authors argued that ULEZ on its own was not an effective strategy 6 House of Commons Library The Expansion of the Ultra Low Emissions Zone Debate Pack 19 December 2022 Number CDP-0240 (2022) by Marguerite Dallas, Iona Stewart, Dr Holly Edwards, Louise Smith 7 Has the ultra-low emission zone in London improved air quality? Liang Ma et al 2021 Environ. Res. Lett. 16 124001