The pace of technological advance in the past few decades has opened new possibilities. Consider the technology for controlling emissions from cars, buses, and trucks. Government regulations have driven this technology as much as the technology has driven regulations, resulting in vehicle emission standards in industrial countries that have become increasingly stringent-far more so than those in developing countries. These standards are deemed necessary to adequately protect the public, especially from excess mortality and morbidity caused by air pollution. But air pollution is much more serious in many developing country cities. Doesn't this argue for imposing standards just as stringent, since the technologies to achieve them are now available? Moreover, since the private sector bears the cost of adopting these technologies, there should be little direct impact on the government budget, removing one of the potential obstacles to implementation.