"Take air quality in the United States today: It's about 30 percent better than it was 25 years ago, even though there are now more people driving more cars"

This quote by Jared Diamond is describing the improvements in air quality in the United States over the previous 25 years. In spite of the reality that there are more people driving more cars and trucks, the air quality in the United States has improved by 30 percent. This is likely due to the execution of more stringent environmental regulations, along with the increased use of cleaner burning fuels and more effective vehicles. In addition, the increased use of renewable resource sources such as solar and wind power has actually likewise contributed to the enhanced air quality. This is a testimony to the development that has actually been made in the United States in regards to environmental protection and sustainability.