Urban air pollution may become the largest environmental cause of death, overtaking dirty water and poor sanitation, according to a report from the Organization for Economic Cooperation and Development (OECD). The report indicates that, by 2050, exposure to particulate matter may cause up the 3.6 million premature deaths per year. In addition, wealthy countries with aging populations will suffer due to ground-level ozone, as older people are more susceptible. "Unless the global energy mix changes, fossil fuels will supply about 85 percent of energy demand in 2050, implying a 50 percent increase in greenhouse gas emissions and worsening urban air pollution," said the OECD in its 2050 environmental outlook. The study said that governments can act quickly to address many of the problems outlined in the report, which included urban air pollution, climate change, biodiversity loss, and water depletion. For instance, though many governments currently tax diesel fuel at a lower rate because it is less polluting in terms of greenhouse gases, it is far worse in terms of particulate matter emissions. "In environmental terms, there is no reason to give diesel tax breaks over petrol," said Simon Upton, environment director at the OECD. In addition, governments could remove subsidies for fossil fuels and activities that encourage water depletion, and should consider whether biofuels are worth the risk of increased biodiversity loss and land use changes. For the full story, see and