There is no threshold level of fine particle pollution below which health risk reductions are not achieved by reduced exposure.

EPA gets to set a standard for new. For the existing, EPA sets guidelines for what we think is appropriate, but then states develop plans that work for them, taking into consideration their specific energy mix.

I definitely challenge people. But hopefully, I am working harder than anybody else, and so people won't resent the fact that I want them to work hard, as well.

People are not running to build coal facilities because of the price of natural gas, but we do see them being constructed, and there is an interest in fuel diversity, so we took the exercise pretty seriously.

There is no threshold level of fine particle pollution below which health risk reductions are not achieved by reduced exposure.

I don't think any administration, when they come in, thinks that their job is to tell the scientists what the science looks like or to be quiet about the science. Scientists need to remain true and not allow science to be politicized. Scientists are not politicians, and no politician should consider themselves to be a scientist.

I think that one of our most difficult international challenges is clearly climate change and making sure that the Paris agreement goes forward. While I think the international community understands that President Trump is not taking the same position as President Obama.