Initiatives

Climate and Health

Global estimated annual PM2.5 concentrations (ICCT working document).

The Climate and Health Program develops strategies and tools to address both public health and climate change. The logic of pairing what might at first glance seem distinct issues is straightforward. Many conventional pollutants do double-duty, trapping heat in the atmosphere as well as causing damage to the heart and lungs. For example, soot emissions, including particulate matter from diesel vehicles, is a significant public health problem; a 2006 World Health Organization study estimated the number of premature deaths worldwide attributable to outdoor PM exposure at 800,000 annually. But particulate matter is also a critical factor in climate change because it contains a high fraction of black carbon, a product of incomplete combustion in vehicle engines that may be the second or third largest contributor to global warming after carbon dioxide.

Efforts to reduce or reverse the rate of global temperature change will also mitigate indirect impacts on health and welfare, such as increases in ground-level ozone concentrations, more frequent and dangerous heat waves, severe flooding, infectious disease, and crop damage from drought or other environmental factors.

But these strategies must be pursued carefully, with attention to corollary effects. For example, tightening carbon dioxide standards might lead to an increase in the number of uncontrolled diesel vehicles in a country’s fleet, with harmful consequences for public health. An ICCT analysis has shown that without adequate controls on diesel emissions of nitrogen oxides and particulates, including black carbon, there may actually be no net climate benefit and the negative impacts on public health may even increase.

Accounting for both climate and public health effects when making policy is vital to an accurate analysis of the costs and benefits of different courses of action. Many steps taken to regulate vehicle emissions have generated health benefits that far outweighed their costs; when combined with climate benefits, they may provide even greater value.

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