Complex sentence: City health officials initially maintained that the smog had not caused any deaths, but a statistical analysis indicated that 168 people likely died because of the smog, and another study found 366 people likely had their lives shortened.
Split into simpler sentences: City health officials initially maintained that the smog had not caused any deaths. However, a statistical analysis indicated that 168 people likely died because of the smog, and another study found 366 people likely had their lives shortened.