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Fine particulate matter (PM2.5, particles smaller than 2.5 μm in diameter) air pollution poses a major risk to public health across the world. While the global burden of exposure to PM2.5 has remained persistently high, some regions – particularly in rich countries in the Western hemisphere – have seen more encouraging signs of progress in reducing impacts. This thesis documents some of this progress for the United States over the last 15 years (focusing primarily on PM2.5 with the exception of Chapter 2), and explores patterns that have started to emerge in more recent years that may inhibit further reductions or indeed point to a potential reversal in trends. In Chapter 1, the thesis provides a broad overview of sectoral contributors to monetized air pollution impacts, which we term gross external damage (GED), in the United States from 2008 to 2014. It notes trends such as the continuation of a steep decline in GED from the utilities sector as well as sectors such as manufacturing which exhibit modest increases in GED coinciding with the economic recovery after the financial crisis. The chapter also highlights that GED in the agriculture sector did not follow a comparable trajectory and instead remained largely stagnant over this time period. In addition to sectoral totals the chapter presents GED to value added (VA) at various sectoral scales. The damage intensities computed thusly provide an indication of a more accurate representation of economic performance because they account for environmental damage caused by economic activity.Chapter 2 expands on the work from Chapter 1 by incorporating GED from greenhouse gas (GHG) emissions and damages and updating the estimates to 2017. A modified sectoral categorization and the inclusion of residential activities and wildfires add more comprehensive estimates of the damages caused by human activities to the picture. GED from wildfires in particular (which are not only caused by humans) have increased substantially in recent years, and this trend has been especially pronounced in Western states. They now constitute a larger share of economy-wide GED than every economic sector, and recent evidence suggests that heavy wildfire seasons cause profound negative impacts to the United States economy. This chapter also argues strongly in favor of the power of regulation as a means to lower environmental impacts from economic activities. Sectors and pollutants that are tightly regulated, such as electricity generation or non-carbon pollutants emitted from transportation, are seeing the most success in lowering emissions and damages, whereas agriculture, a sector with precious few regulations on air pollutant emissions, is seeing hardly any progress. In some sectors (particularly in transportation), GHG GED are on an upward trajectory while GED from PM2.5 are falling, offering perhaps the clearest evidence of regulatory efficacy. The last chapter of this thesis provides detailed estimates of industrial GED within the agriculture sector at a national, state and metropolitan statistical area (MSA) level for 2011, 2014 and 2017. It improves upon the attribution method used to compute agriculture GED in Chapter 1 and thus provides more geographic and sectoral detail. Once again GED is compared with economic indicators such as gross domestic product (GDP) or VA, which adds nuance to the results. GED intensities by area differ significantly from GED compared to economic value. One key insight from this chapter is the strong concentration of agriculture GED from activities near population centers ¬ approximately half of all agriculture GED is a result of emissions that occur within the boundaries of metro areas. Overall, the thesis documents some encouraging trends in reducing the impacts from air pollution in the United States over the last decade and more, yet also identifies areas where progress has been mixed, muted, or even non-existent, and should therefore provide policymakers in the United States with useful information when it comes to designing the future regulatory framework for dealing with air pollution. |
