Yes, if the U.S. wants to be seen to pursue sustainable development for its own citizens and globally, then it must push for tougher regulations on greenhouse gases. These regulations should, in my opinion, include a large increase in the cost of CO2 emmissions, as high as $1000 per CO2 tonne has been suggested by a reputable source. This would provide economic incentive for power stations to develop CO2 capturing technologies, for example.
The U.S. needs to have tougher regulations on ozone pollution put in action. The present policies in place are very vague when it comes to how we handle ozone pollution. The policy need to change immediately because of the climate change. We don't know how climate change and pollution will effect the ozone. Those two factors alone, unregulated, could have an adverse effect on us.
No, I do not think that the U.S needs tougher regulations on ozone pollution because everywhere in the world we are all doing our best to stop all the pollution and keep our air clean but there is really only so much that we can do and I think we are all already doing everything we can.
There are far more pressing environmental issues that need to be addressed rather than ozone pollution, which would have a much more substantial impact on both pollution and human health if they were more strongly regulated. Reduction in coal use, for example, would have a much more positive effect on air quality than tightening automobile exhaust standards (the main source of ozone--and already highly regulated by the EPA).