Elgin isn't one of the best places to live in America according to CNN/Money Magazine (boohoo!). But at least its a contender. And apparently it has very good air. The average score for the best places is on the right and Elgin's score is on the left column. 100 is the national average; the lower the score the better:

Air pollution index	55	90
Personal crime risk	72	69
Property crime risk	52	78

Elgin scores better than the best places average for property crime, and trails the best places average for personal crime only slightly. That's pretty good considering the size of the city (look at Rockford and Peoria's crime numbers--worse than Elgin's by orders of magnitude). Also interesting is that Elgin's student to teacher ratio is better than Naperville, which was ranked as the 3rd best place to live in America.

See for yourself how Elgin stacks up:
Elgin
Naperville
St. Charles
Aurora
Peoria
Rockford