Cannabis and Respiratory Health

Cannabis legalization has increased substantially in the past two decades with state-level policies that permit possession this product. A potential concern with cannabis legalization and the corresponding increase in consumption is that – because smoking is the most common consumption mode – respiratory health could worsen. In this study, we offer new evidence on the impact of recreational cannabis laws on asthma outcomes. To do so, we combine commercial health insurance claims and survey data over the period 2008 to 2022 with difference-in-differences and event-study methods. Our findings suggest that asthma diagnoses do not change following legalization of recreational cannabis, while asthma-related dispensed prescription medications decline, and asthma-related outpatient visits and inpatient hospitalizations are stable. An analysis of changes in use of smoked and non-smoked cannabis post-law suggests that, on net, the increase in overall cannabis use attributable to legalization is driven by use of non-smoked cannabis, which may explain why we find limited evidence that asthma outcomes worsen post-law. Collectively, these results suggest that expanded access to legal cannabis has not worsened respiratory health overall, and hint that some patients may use cannabis to manage asthma symptoms.