Air Pollution as a Climate Forcing: A Workshop

Day 4 Presentations

Air Pollution Health Benefits and Greenhouse Gas Reductions: A Case Study in Chile

Luis A. Cifuentes
Industrial and Systems Engineering Department, P. Universidad Católica de Chile, Santiago, Chile

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While local air pollution has been a problem in developing countries for some time, climate change is looked upon as a developed world problem. In the face of many more immediate needs, not many efforts are devoted to mitigate GHG emissions. In this work we present a case study of the interaction of measures to abate air pollution and measures to mitigate GHG emissions in Chile. Two types of analysis are considered: i) a global analysis, in which the health benefits associated with a GHG mitigation scenario are estimated, and ii) a detailed mitigation measures analysis, in which both GHG and local air pollution reductions are estimated, and their social benefits compared.

For the first analysis, a moderate "Climate Policy" scenario was considered. This scenario has been developed for the Chilean National Environmental Commission, and considered only non-positive costs measures, like efficiency improvements in the industrial and residential sectors. The level of carbon abatement of this scenario is modest: 13% reduction from the Business-As-Usual scenario. Emission reductions of local air pollutants (CO, SO2, Voss, NOx, resuspended dust and PM10) were estimated from emission factors recommended by the IPCC. These percentage reductions were applied uniformly to major urban areas of Chile with measured particulate matter concentrations. The health benefits due to air pollution abatement were computed using figures derived previously for the cost benefit analysis of Santiago's Decontamination Plan, transferred to the different cities taking into consideration local demographic and income data. The Santiago estimates were obtained using the damage function approach, based on some local epidemiological studies, and on local health and demographic data. Unit social values for the effects were estimated locally (for cost of treatment and lost productivity values) or extrapolated from US values (mainly for WTP values) using the ratio of per-capita income and an income elasticity of 1. The average benefits of emission abatement (in 1997 US$ per ton) are 1,800 (1,200-2300) for NOx, 3,000 (2,100-3900) for SO2, 31,900 (21,900 - 41,900) for PM, and 630 (430 - 830) for resuspended dust. These benefits were updated in time using the expected population and per-capita income growth. Dividing the health benefits accrued from the local air pollutant emissions reductions by the amount of carbon abated, average ancillary benefits of 69 (30-260) and 104 (50-380) US$ per ton of carbon abated are achieved for the years 2010 and 2020.

The second type of analysis involved the detailed analysis of specific mitigation measures in Santiago. Most of the measures considered were primarily aimed at local air pollution abatement, like technology changes in public transport buses, but some were energy efficiency measures. The emissions reductions of both GHG and local air pollutants were estimated from emission factors (some derived locally) and changes in activity levels. The figure shows the relation between reductions in carbon equivalent and PM2.5 precursors (the percentage change was based on the relative contribution of unit pollutant emissions to ambient concentrations during Santiago's winter).

Scatter2 equivalent and in local air pollutants" border="0">

Figure 1: Percentage reductions in CO2 equivalent and in local air pollutants for selected measures.

As is clear from Figure 1, most of the measures have a bigger reduction in local air pollution. Two measures (CNG conversion of existing diesel buses, and extended life-span of existing diesel buses) have zero or negative air pollution reductions, while particulate traps for diesel buses have negative carbon reductions. Next, the benefits from local air pollution abatement and carbon reduction were compared.

Values of 20 and 50 US$/tCe were considered for valuing the carbon reductions, while the previously shown values were considered for local air pollutant reductions.

A comparison of the benefits shows that health benefits are generally much higher than carbon benefits. For the fuel switching measures, carbon benefits are just 9% to 28% of the health benefits (the latter figure for the 50 US$/tCe case for diesel to NG switch in boilers). In the transportation sector, the ratio goes from zero to 13% for hybrid electric buses. The electricity savings measures vary from 5% to 12%.

In terms of offsetting some of the costs of the measures in the transport sector, at 20US$/tCe, carbon credits would account for just 0.6% of the annual costs of CNG buses, for 2.6% for the CNG conversion of existing buses, and for 15% of those of hybrid-electric buses. The figures increase to 1.5%, 6% and 37% if carbon reductions were valued at 50 US$/tCe.

These results show that the local pollution health benefits of reducing GHG emissions are significant, both for the scenario analysis and for the mitigation measure analysis. The public health benefits of carbon reduction measures can offset most of the cost of GHG reduction. However, for most measures analyzed, the public health benefits are an order of magnitude greater than the benefits from carbon reduction. Also, the cost offsets due to potential carbon credits are limited from a few % up to 37% in the best case. This suggests that the main driver for air pollution policy is likely to continue to be local concerns, such as public health issues.

Acknowledgments. This was has been partially funded by National Renewable Energy Laboratory, subcontract N. AMD-9-29778-01 under prime contract N. DE-AC36-99GO10337, and by the Chilean Commission on Science and Technology, Projects Fondecyt 1970117, 1970114, and by the Center for Integrated Study of the Human Dimensions of Global Change, a joint creation of the National Science Foundation (SBR-9521914) and Carnegie Mellon University.

Workshop Homepage * Background
Summaries: Overview, Gases, Aerosols, Tech., Health, Agri./Eco.
Abstracts: Day 1, Day 2, Day 3, Day 4, Day 5 * Participants