Colder Spark Plug Reduce NOx?

[landtoy80]

Is there any truth that if you use one step colder spark plug, that will reduce NOx? Will it increase other emissions?
I have no idea how the a hotter or colder spark plays a part in the combustion chamber.

 

[unklwedy]

Egr introduces previously combusted gases to combustion chamber and reduces combustion temperatures which reduces NOX.
Don't think colder plug reduces NOX.