what do mean by emission broadning?

Answer 1

There are several mechanisms for broadening spectral lines. Two of the most prominent are Doppler broadening and Collision Induced broadening. For Doppler broadening, the natural line shape is convoluted with a Gaussian with half-width related to the distribution of molecular (or atomic) velocities in the sample. Collision Induced broadening convolutes the line shape with a Lorentzian function with width related to the sample pressure.

Answer 2

there are different types of emmisions from different sources, and broadening emissions standards would mean including more types of substances in the already massive list of pollutants