[The effect of air pollution on human health].

Heidi Wald, a professor at the CU School of Medicine who helped run the study, said the results come with caveats. The project didn’t have a control group, so it did not measure whether opioid use also dipped at hospitals that did not participate in the program. The results presented Thursday also did not include measurements of patient satisfaction, which would reveal whether the alternatives controlled pain as well as opioids.