Since secondary sulfates make up about 50% of fine particles in the atmosphere in some regions of the United States, sulfur emission reduction will likely be required to help meet PM 2.5 ;
(secondary sulfates; make up; about 50% of fine particles) (sulfur emission reduction; will likely be required; to help meet PM 2.5) (sulfur emission reduction; to help; meet PM 2.5)
secondary sulfates sulfur emission reduction sulfur emission reduction
make up will likely be required to help
about 50% of fine particles
to help meet PM 2.5
meet PM 2.5