Exploring the Impact of Mask Mandates on Human Movement and Social Contact

During the onset of the COVID-19 pandemic, the implementation of state-wide mask mandates entered the forefront of the discourse on public health policy. While mask mandates have been shown to slow the spread of the virus, it is unclear whether the implementation of the policy has an effect on human movement and social contact. This paper aimed to determine the existence of such a relationship and to quantify its effect. The opportunity for this investigation arose from the difference in policymaking among states—some states opted to enact mask mandates while others abstained. The analytic approach employed a difference-in-differences (DID) model to compare the two groups of states, using a device exposure index (DEX) that tracks smartphone data as a measure of human mobility. To maintain the comparability of mask mandate and non-mask mandate states, only states that border each other were analyzed. Results from the DID analysis showed a generally negative relationship between mask mandate implementation and DEX; that is, the enactment of mask mandates was associated with a decline in human mobility as measured by device exposure. However, some state comparisons yielded positive and nonsignificant effects as well, indicating that the policy intervention had no clear, unidirectional effect on human mobility. Further analysis using the mobility and engagement index and the generalized synthetic control method reaffirmed the indeterminate effect of mask mandate implementation, demonstrating the need for further analysis on a more granular, county-level basis.