Climate change and health

Sari Kovats and Andrew Haines, in their commentary on the interrelationship between global climate change and health,¹ comment on the increase in deaths from extreme heat in Europe, particularly France, during summer 2003. It is important to note that some of these deaths were due to the elevated tropospheric ozone levels that accompanied the high temperatures.² In the Netherlands, about 400 deaths were attributed to ozone,³ and similar calculations have been done for France and Britain.

In 1990, I reviewed the implications of global warming at a parliamentary conference,⁴ noting that increased ozone levels would occur unless precursor emissions were reduced. Neither Canada nor the United States has succeeded in effecting major reductions in the emissions of oxides of nitrogen, and these are still substantial, as illustrated in a recent newsletter from the North American Commission for Environmental Cooperation.⁵ It has also recently been documented that tropospheric ozone levels are slowly rising over the North Atlantic.⁶

Fortunately, any steps taken to reduce carbon dioxide emissions will also reduce oxide of nitrogen emissions, with a consequent lowering of ozone levels. All physicians should agree with Kovats and Haines that it is urgent for Canada not only to implement the Kyoto Protocol but also to take an international leadership role in urging much greater reductions.

David V. Bates Professor Emeritus of Medicine University of British Columbia Victoria, BC