Estimated Relative Benefits of Interventions
Based on case studies and expert judgment
Intervention By Sector
Using No. 10 as an example we can see that reducing very high sulfur content in diesel fuel, is not difficult, (green) and is very effective, (a large circle). Lower sulfur fuels result in less PM2.5 and other toxic emissions, so are less dangerous to breath (high health benefits), but because the fuel is still carbon-based, there are not significant CO2 reductions relative to other interventions, hence its position in the upper left quadrant of the chart.
NOTES TO FIGURE
This figure was developed in order to provide a concise overview of the relative effectiveness of all the interventions assessed. It was prepared by the study team and reviewed and revised in discussions with the review group.
The data necessary to quantify the benefits is not available; and therefore, the team used experience and professional judgment to estimate both health benefits and climate change benefits in terms of their relative size and general magnitude. Health benefits were treated as estimated reductions in ambient PM2.5 as a result of the intervention, assuming that implementation was broadly successful. Climate benefits were estimated as reductions in the tons of CO2. The figure refers to interventions designed to reduce air pollution and therefore does not include actions designed specifically intended to reduce other greenhouse gas emissions, such as methane or HFCs.
General guidance in initially classifying the benefits was given to reviewers in the following terms.
PM2.5 levels are used as proxy.
Metric is tonnes of CO2 equivalent reduced:
This is considered as the direct cost to government coffers – the funding that the implementing agency has to provide. Clearly, there will often be considerable direct costs to industry or to individuals in actually putting the intervention into practice. These costs are considered in the context of a major city.
This is a judgment on how straightforward the interventions would it be to implement, especially in cases where the government directs an action that imposes costs on others. Issues could include possible public outcry against increased costs; resistance from companies; objections from utilities who would have to implement; and/or possible interagency complexities.
Estimates were made separately for each intervention and plotted accordingly. Revisions and adjustments were made to reflect consensus views, particularly on the relative positioning of some interventions. With more data and analytical effort it would be possible to refine some of these estimates. Readers are encouraged to make these calculations and to share the results publicly.