Modeling the Air Quality and Asthma Impacts under a Four-Day Workweek: Health and Economic Implications for Urban Policy
Author(s): Aiyer P, Surani SR, Mominkhawaja A, Sheta A
Purpose: The four-day workweek appears to be a viable implementation, assuring improvements in work-life balance and traffic congestion, among other benefits. This paper explores changes in several key air quality indices—NO2 (nitrogen dioxide), PM2.5 (particulate matter), and AQI (air quality index)—between weekdays and weekends, in order to estimate the potential economic and health impacts of an extended three-day weekend, based on the volume of asthma-related emergency department visits. Methods: Daily air quality data for the three air quality indices were downloaded from the U.S. EPA Air Quality System for the year 2023, representing real-time pollutant concentrations. Then, a t-test for paired samples was conducted to determine any statistically significant differences at the 0.01 significance level, comparing averaged weekday (Monday to Friday) pollutant levels with those of the weekend (Saturday to Sunday). For the simulation of a four-day workweek intervention, a counterfactual scenario was modeled. Under this intervention, one weekday NO2 level was replaced with the weekend mean based on the observed reduction in traffic-related emissions. Modeled NO2 reductions were applied to a validated exposure-response coefficient linking a 4% increase in asthma exacerbations to a 1 μg/m³ rise in NO2 levels. Baseline asthma-related ED visits for Los Angeles County (n = 33,234 annually) were stratified into pediatric (0–17 years, 12,680 visits) and adult (18+ years, 20,554 visits) categories. The total number of ED visits prevented was calculated proportionally using the modeled NO2 reductions. Healthcare costs were estimated using a median cost of $1,502 per ED visit, and total economic savings were quantified. Results: Of the three air quality indices analyzed, only NO2 showed significant differences between weekdays and weekends. Weekday NO2 levels averaged 23.86 ± 6.72 μg/m³, compared to 20.14 ± 5.86 μg/m³ on weekends (p < 0.01). PM2.5 and AQI exhibited no significant changes, indicating that NO2 is the most responsive pollutant to traffic-related emissions. Modeling a four-day workweek intervention reduced weekday NO2 levels to 22.27 μg/m³—a reduction of 1.59 μg/m³. That reduction, applied to the exposure-response relationship developed and validated in the study, was believed to represent a 6.38% reduction in asthma exacerbations. Health impacts included an estimated 2,121 avoided asthma-related emergency department (ED) visits annually, stratified by 810 pediatric and 1,311 adult visits. Respective healthcare cost savings totaled $3.19 million per year, reflecting high economic returns due to NO2 emissions reduction. These results provide insight into the real-world feasibility of a weekend extension in mitigating vehicular pollution and its potential impact on society. Conclusions: This study demonstrates that a four-day workweek intervention can significantly reduce weekday NO2 emissions, with no significant effects observed for PM2.5 and AQI. By targeting NO2, the most responsive and actionable pollutant, this intervention could prevent over 2,100 asthma-related emergency department (ED) visits annually and generate $3.19 million in healthcare cost savings in LA County, and suggests that this may be only the tip of the iceberg regarding the possible global impact from asthma, which can be mitigated with a reduction in pollution that a shorter four-day workweek enables. Clinical Implications: These findings have significant implications for establishing a four-day workweek as a viable, scalable public health intervention to reduce trafficrelated NO2 emissions and improve respiratory health. NO2-directed strategies, such as extra-long weekends, low-emission zones, and fleet transition to cleaner transportation technologies, should be at the top of the list of policy priorities for consequential, reproducible health and economic benefits.