Transparency is all about letting in and embracing new ideas, new technology and new approaches. No individual, entity or agency, no matter how smart, how old, or how experienced, can afford to stop learning.

We need an international solution to the challenge of climate change, there's no question about it. But the real key is, can you actually get that - or get that solution - without the US' involvement? Can you not lead domestically, and expect the rest of the world will take action... the US needs to lead, we need to be out there.

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.

When discussing overall impacts on employment, it is important not to overlook the new technologies and industries that can be driven by pollution control standards.

The climate change is real today, but also the solutions that we have available to us that are cost-effective and beneficial to everyone are at our disposal now.

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.

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