CAA §615 provides the EPA Administrator authority to promulgate regulations controlling any substance anticipated to affect the stratosphere to the detriment of public health and welfare. This authority has never been utilized for any pollutant, and its application would be subject to some legal uncertainty. EPA may also seek to classify nitrous oxide as a class I or class II substance under §602, but the phaseout of production and consumption mechanisms available under that section would only impact a very small amount of nitrous oxide, since the majority of nitrous oxide pollution is not the result of deliberate production or consumption.