As some of the above-linked articles eventually get around to noting, this report shows a mathematical association between traffic air pollution components in a certain range, as the authors calculated them, and an increased autism risk.

FORBES: 5 Caveats About The Autism And Air Pollution Study

The authors broke down air pollution exposure into ranges (quartiles) and then presented odds of autism in relation to each exposure range for different time points.

FORBES: 5 Caveats About The Autism And Air Pollution Study