Two new studies by COEH member Kirk Smith show how mitigation strategies to reduce global warming often improve public health by reducing risks for disease and mortality, particularly in the world's poorest and most vulnerable nations.
Smith's research formed part of a Health and Climate Change series in The Lancet that examined mitigation strategies in four sectors: household energy; urban transport; electricity generation; and food and agriculture, with a separate evaluation of the role of short-lived greenhouse pollutants. The series was timed to inform discussions at the December 2009 UN Climate Change Conference in Copenhagen.
The first article co-authored by Smith, professor of global environmental health at UC Berkeley, used hypothetical case studies in the UK and India to identify co-benefits realized through interventions within the household energy sector.
Researchers estimate that, in the UK, household insulation, ventilation, fuel switching and behavioral interventions would result in 850 fewer disability-adjusted life years (DALYs) and 89 fewer premature deaths, and a savings of more than half a megaton of carbon dioxide (CO2) per million population per year.1
In India, introducing 150 million low-emission household cookstoves produced an estimate of 12,500 fewer DALYs and a savings of up to 0.2 megatons of CO2 per million population per year.2
In total, over the 10 years of the stove introduction, more than 2 million premature deaths would be avoided from childhood respiratory infection, chronic obstructive pulmonary disease and ischemic heart disease.
Currently, the use of household biomass fuel accounts for nearly half a million premature deaths in India per year, reports Smith. The majority occur in children under five due to acute respiratory infections such as pneumonia.3
The second study in The Lancet, conducted by an international team including COEH member Michael Jerrett, professor of environmental health sciences at UC Berkeley, is the first comprehensive review to jointly examine the health effects of short-lived greenhouse pollutants —sulfates, elemental (black) carbon and ozone. Black carbon and ozone exert health effects and have global warming potential. In contrast, sulfates exert health effects, but act to cool the atmosphere.
Researchers conducted a meta-analysis of existing time-series studies, a toxicological review, and a cohort study of 352,000 people followed for 18 years in 66 US cities. The cohort study was the first to examine the joint effects of ozone, black carbon and sulfates with mortality.
Study authors also reported the first estimates of the health effects of elemental carbon on long-term mortality risk.
The pollutants causing most of the direct damage to human health from energy use worldwide are also all climate-active, some warming and some cooling.4
"Interventions targeted to reduce short-lived pollutants in the atmosphere would produce health benefits within days, if not weeks, and lead to reductions in global warming," said Jerrett.
"For black carbon and ozone, this would also be accompanied by quick reductions in climate impact," added Smith. "For sulfates, however, there is an unfortunate inverse relationship. Needed reductions in sulfate levels to protect health will reduce the sulfate cooling that now partly counteracts warming produced by other climate-active pollutants, such as CO2."
1, 2 Wilkinson P, Smith KR, Davies M, Adair H, Armstrong BG, Barrett M, Bruce N, Haines A, Hamilton I, Oreszcyn T, Ridley I, Tonne C, Chalabi Z. Public health benefits of strategies to reduce greenhouse-gas emissions: household energy. The Lancet. 2009 Dec;374(9705):1917-29.
3 World Health Organization, Regional Health Forum WHO South-East Asia Region (Volume 7,Number 1)
4 Smith KR, Jerrett M, Anderson HR, Burnett RT, Stone V, Derwent R, Atkinson RW, Cohen A, Shonkoff SB, Krewski D, Pope CA 3rd, Thun MJ, Thurston G. Public health benefits of strategies to reduce greenhouse-gas emissions: health implications of short-lived greenhouse pollutants. The Lancet. 2009 Dec;374(9707):2091-103.
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