Abstract
Background: It is often argued that liquid biofuels are “cleaner” than fossil fuels, and by implication, better for human health. However, the literature on this issue is not clear. Brazil's high uptake of ethanol and its role as a major producer of the fuel makes it the most appropriate case study to assess the potential merits of different biofuel policies. In this study, we evaluated the impact on air quality and health of two future fuel scenarios in São Paulo State: a business-as-usual scenario where ethanol production and use proceeds according to government predictions (a nationwide increase of 3,800 MW from 2010-2020) and a counterfactual scenario where ethanol use is frozen at 2010 levels (5,300 MW) and all future transport fuel demand is met with gasoline. Methods: Concentrations of particulate matter (PM2.5) and ozone were modeled for the state of São Paulo in 2020 at a 10km x 10km resolution using the CATT-BRAMS atmospheric chemistry transport model. Health impacts from multiple causes of death were estimated with life table methods using concentration-response functions from studies of long-term exposure. Results: The population-weighted annual average exposure to PM2.5 was 3.0 μg/m3 higher in 2020 in the business-as-usual (ethanol expansion) scenario compared to the scenario that emphasized gasoline, with the biggest differences in urban areas. The corresponding figure was 0.3 ppb for ozone (average of summer 1-hour maximums). The higher exposure in the ethanol scenario would result in the State's population living 1,200 fewer life-years in the first year, and if sustained, would rise to 43,000 life-years lost in year 20. Estimates assume no temporal trend in population health attributable to other causes. Conclusion: Without additional measures to limit emissions, increasing the use of ethanol in Brazil is likely to lead to higher air pollution-related health burdens when compared to a transport fuel policy that instead prioritizes gasoline.
Highlights
As one of the few alternatives to fossil fuels in the transport sector, liquid biofuels have received increased attention for their potential to help mitigate climate change, improve energy security, and revitalize agricultural economies
In 60% of municipalities, the annual average concentration of PM2.5 was higher in the Ethanol Expansion compared to the Fossil Fuel scenario, but there was marked seasonal variability: 100% of municipalities were higher in summer in the Ethanol Expansion scenario but only 19% in winter (Figure 3)
This study suggests that a transport policy promoting ethanol over gasoline would result in more particulate air pollution and higher levels of tropospheric ozone in São Paulo State
Summary
As one of the few alternatives to fossil fuels in the transport sector, liquid biofuels have received increased attention for their potential to help mitigate climate change, improve energy security, and revitalize agricultural economies. Public Health 2016, 13, 695; doi:10.3390/ijerph13070695 www.mdpi.com/journal/ijerph
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