The effect of the Safer at Home order on the frequency of DUI breath alcohol tests in Los Angeles County.

With Los Angeles County having a population size of just over 10 million and an additional 471,000 people who commute into Los Angeles County for employment, many drivers are at risk of being injured or killed in an alcohol-impaired driving collision. On March 19, 2020, the County of Los Angeles issued the Safer at Home order as a result of the COVID-19 pandemic. This curtailed driving and decreased the number of breath alcohol tests that were conducted in Los Angeles County. The number of breath tests conducted in January-February of 2019 and 2020 and March-April of 2019 and 2020 were evaluated using Fisher's exact test and analysis of variance. There was a statistically significant decrease in the overall number of breath tests conducted in Los Angeles County in March-April of 2020. There was also a significant decrease in the number of collisions where DUI was a factor. Accounting for changes in traffic volumes, the number of breath tests per vehicle miles driven also decreased significantly. Since the Safer at Home order closed all non-essential services such as bars and restaurants, there is indirect data on the relative contribution of liquor-serving establishments, and to some extent large social gatherings, to the incidence of drunk driving. Taking into account traffic volume, it was determined that the odds of encountering an intoxicated driver decreased by approximately 23% during the Safer at Home period. This information could help policy-makers determine the likely effectiveness of various countermeasures to prevent drunk driving.