Trump's claim that US is cleanest lacks support from studies

Is the United States the cleanest and most environmentally friendly country on Earth? President Donald Trump says it is, but some studies of the American environment don't agree.
Data show that the US is among the dirtiest countries when it comes to heat-trapping carbon pollution. One nation that has cleaner air in nearly every way is Sweden.
In fact, the US emits more carbon dioxide than any other nation except China.
Taking into account economics, the US ranks 10th highest in carbon pollution per gross domestic product. China is No. 1, followed by India and Russia.
In some traditional air pollution measurements, the United States is cleaner than most nations. The US is better than most of the world when it comes to dangerous soot or fine particles.