Aiyer P¹, Surani SR^2*, Mominkhawaja A³, Sheta A³

¹The Quarry Lane School, Dublin, CA, United States

²Division of Pulmonary Medicine, Texas A&M University, Corpus Christi, TX, United States

³Texas Tech University, Lubbock, TX, United States

⁴Department of Computer Science, Southern CT State University, New Haven, CT, United States.

^*Corresponding Author: Surani SR, Division of Pulmonary Medicine, Texas A&M University, Corpus Christi, TX, United States.

Received: 06 July 2025; Accepted: 14 July 2025; Published: 23 July 2025.

Article Information

Citation: Aiyer P, Surani SR, Mominkhawaja A, Sheta A. The Health and Economic Benefits of a Four-day Workweek: Modeling Air Quality Improvements and Asthma Impacts. Journal of Environmental Science and Public Health. 9 (2025): 29-37.

DOI: 10.26502/jesph.96120219

Abstract

Keywords

Four-day workweek, Nitrogen dioxide, Air quality, Traffic, Pollution.

Article Details

1. Introduction

The concept of a four-day workweek has gained traction in recent years, primarily as an intervention aimed at improving work-life balance, reducing employee burnout, and enhancing productivity. Trials conducted in countries such as Iceland, Japan, and the United Kingdom have demonstrated promising outcomes, including sustained economic performance, increased worker satisfaction, and improved mental health among employees [1, 2]. While the social and economic benefits have been extensively tested, the environmental and health impacts of this intervention remain underexplored. A reduction in workdays has the added potential to decrease commute traffic, a major and modifiable factor contributing to urban air pollution, thereby leading to significant improvements in air quality and its related public health effects [3, 4].

Among the most pressing global public health concerns, the issue of air pollution remains at the forefront. As per the World Health Organization (WHO), around 99% of the global population consistently breathes air that surpasses the recommended limits for PM2.5, nitrogen dioxide (NO₂), and ozone [5]. These pollutants are commonly associated with the progression of COPD, exacerbation of asthma, and increased emergency department (ED) visits [6, 7]. In Los Angeles, as in other urban areas where traffic emissions are a major source of pollution, NO₂ levels often exceed 18 ppb, posing significant health risks, particularly for vulnerable populations, such as children and older adults [8, 9]. Observational studies have consistently demonstrated a “weekend effect,” where air quality improves significantly during weekends due to reduced traffic volumes [3, 10].

Given the well-documented link between air quality and respiratory health, structural changes to work schedules—such as a four-day workweek—present an innovative yet underexplored opportunity to address pollution and its associated health burdens. While prior research has studied the impact of reduced traffic on air quality during weekends, few studies have investigated the application of this phenomenon to policy-driven interventions, such as a four-day workweek [11, 12]. The extent to which key air quality indices such as NO₂, PM2.5, and Air Quality Index (AQI) would respond to such a change, and the resulting health and economic benefits, remains unclear.

The purpose of this study has two primary objectives: 1) to note changes in the three air quality indices (NO₂, PM2.5, and AQI) from weekdays to weekends, implementing real-world air quality statistics, and 2) to model the potential impacts of implementing a four-day workweek by estimating reductions in traffic emissions and the resultant decrease in asthma-related ED visits. This study implements a data-driven structure in order to assess the viability of a four-day workweek by integrating factors within environmental science, public health, and policy analysis. The findings aim to provide crucial insights for policymakers and public health officials who seek to mitigate pollution, enhance respiratory health, and reduce healthcare costs in urban areas.

2. Methods

2.1 Data Collection

Daily air quality data for Los Angeles County was obtained from the U.S. Environmental Protection Agency, Air Quality System, a reliable repository for real-time and historical pollution monitoring. Three key indices were analyzed: nitrogen dioxide (NO₂), fine particulate matter (PM2.5), and the Air Quality Index (AQI), spanning the year 2023 [13]. Weekdays were classified as Monday to Friday, while weekends consisted of Saturday and Sunday for comparison. Data on asthma-related health in Los Angeles County were obtained from publicly available state health department reports and the California Department of Public Health. These data provided baseline emergency department (ED) visit rates for asthma, stratified into pediatric (0–17 years) and adult (18+ years) populations [14, 15].

To ensure consistency and scientific rigor, data completeness was assessed using standard procedures, excluding days with missing or flagged entries. Pollutant levels were aggregated to generate mean values for weekdays and weekends, expressed as mean ± 2 standard deviations (SD). IRB approval was not required as the public available data source was utilized.  No patient identifiers were present in the public available database.

2.2 Statistical Analysis

A paired t-test was performed to compare weekday and weekend pollutant concentrations for NO₂, PM2.5, and AQI. This statistical test was chosen for its robustness in evaluating repeated measures on the same group, allowing for the detection of significant differences between weekday and weekend air quality levels [16, 17]. Statistical significance was set at p < 0.05.

2.3 Four-day Workweek Intervention Modeling

A counterfactual scenario was modeled to simulate the impact of a four-day workweek on NO₂ concentrations, assuming proportional reductions in weekday vehicular emissions. Specifically, one weekday NO₂ level was replaced with the observed mean weekend NO₂ level. The change in NO₂ levels was calculated as:

NO₂ Weekday Reduction=Observed Weekday NO₂−Mean Weekend NO₂

This modeled reduction was applied uniformly across the year to simulate the hypothetical intervention. While PM2.5 and AQI were analyzed for completeness, NO₂ was prioritized due to its well-established sensitivity to traffic emissions [18, 19].

2.4 Health Impact Assessment

To estimate the effect of NO₂ reductions on asthma-related exacerbations, we applied a validated exposure-response coefficient: a 4% increase in asthma exacerbations per 1 µg/m³ increase in NO₂ concentration [20]. This relationship has been corroborated in multiple epidemiological studies and meta-analyses linking NO₂ exposure to asthma outcomes [21]. The total annual reduction in asthma exacerbations was calculated using the following equation:

Percentage Reduction in Exacerbations = Change in NO₂ (µg/m³) × 4%

The percentage reduction was applied to baseline asthma ED visit rates for both pediatric and adult populations to estimate the number of annual ED visits prevented.

Annual ED Visits Prevented = Baseline ED Visits × Percentage Reduction

Stratified estimates were generated for pediatric and adult groups to provide age-specific impacts, as children are disproportionately sensitive to traffic-related pollutants [22, 23].

2.5 Economic Analysis

The economic impact of the four-day workweek intervention was estimated based on healthcare cost savings resulting from reduced asthma-related emergency department (ED) visits. A median cost of $1,502 per ED visit was applied, as derived from peer-reviewed cost-of-illness studies focusing on asthma exacerbations in urban populations [24]. The total cost savings were calculated as follows:

Annual Cost Savings = Annual ED Visits Prevented × Cost per ED Visit

All economic estimates were inflation-adjusted to 2023 U.S. dollars for comparability [25].

Table 1: Modeled NO₂ Reduction and Estimated Health Impact Under a 4-Day Workweek

Estimated reduction in NO₂ levels under a 4-day workweek scenario and the corresponding decrease in asthma-related emergency department visits, highlighting the potential air quality and public health benefits of reduced weekday traffic emissions.

3. Results

Analysis of air quality indices for Los Angeles County showed clear diurnal variations in pollutant levels between weekdays and weekends, with NO₂ demonstrating the highest sensitivity to vehicular emission. The average NO₂ concentrations on weekdays were 23.86 ± 6.72 µg/m³, while the weekend mean was 20.14 ± 5.86 µg/m³, with a statistically significant reduction of 3.72 µg/m³ (p < 0.01). This trend aligns with previous studies on the impact of traffic patterns on urban air quality, as vehicle emissions are a major source of NO₂ [18, 19]. In contrast, PM2.5 and AQI showed no statistically significant changes. Weekday PM2.5 averaged 12.48 ± 3.91 µg/m³, compared to 12.32 ± 3.76 µg/m³ on weekends (p = 0.42). Similarly, AQI levels remained stable, with weekday and weekend means of 48.7 ± 9.5 and 47.9 ± 9.2, respectively (p = 0.51). See Figure 1.

Figure 1: Weekday vs. Weekend Pollutant Levels (NO₂ and PM_2.5). NO₂ levels significantly decrease on weekends, while PM_2.5 remains stable, highlighting NO₂’s sensitivity to traffic-related emissions.

Mean NO₂ and PM_2.5 levels on weekdays (red) and weekends (green) with standard deviation error bars. NO₂ levels show a significant reduction on weekends, while PM_2.5 levels remain relatively unchanged, suggesting that NO₂ is more responsive to traffic-related emissions.

To assess the potential impact of a four-day workweek, a counterfactual scenario was modeled, replacing one weekday’s NO₂ levels with the weekend mean under the assumption of proportional reductions in traffic emissions. In this simulation, weekday NO₂ concentrations decreased to 22.27 µg/m³, representing a 1.59 µg/m³ reduction relative to current weekday levels. This reduction is illustrated in Figure 2, which shows the alignment of NO₂ concentrations on modeled weekdays with weekend patterns, demonstrating how structural changes in work schedules can improve air quality. Additionally, this simulation highlights the disproportionate contribution of weekday traffic to urban NO₂ levels and underscores the potential of policy-driven interventions as an effective countermeasure to this issue.

Figure 2: Modeled NO₂ Levels Under a 4-Day Workweek Scenario. Aligning one weekday with weekend NO₂ levels results in a modeled reduction of 1.59 µg/m³, reflecting the impact of reduced traffic emissions.

Observed weekday and weekend NO₂ levels compared to a hypothetical 4-day workweek model. The modeled intervention reduces weekday NO₂ concentrations (green dashed line) by aligning one weekday with observed weekend levels, highlighting the potential air quality benefits of reduced vehicular emissions.

To quantify the health implications of these reductions, a validated exposure-response coefficient was applied, indicating a 4% increase in asthma exacerbations per 1 µg/m³ NO₂ [26]. The modeled reduction of 1.59 µg/m³ was associated with a 6.38% decrease in asthma exacerbations. Applying this reduction to baseline data for Los Angeles County, with 33,234 asthma-related ED visits reported in 2022, this intervention was estimated to prevent 2,121 annual ED visits. Pediatric patients (0-17 years) accounted for 810 fewer visits avoided, while adult patients accounted for 1,311 fewer visits [Figure 3]. This result again highlights the substantial public health burden from traffic-related NO₂ exposure and the greater vulnerability of children to air pollution.

Figure 3: Impact of a 4-Day Workweek on Asthma-Related ED Visits and Healthcare Costs. Projected NO₂ reductions lead to 2,121 fewer ED visits annually and $3.19M in savings, with significant pediatric and adult health benefits.

Modeled reductions in NO₂ levels under a 4-day workweek were used to estimate annual reductions in asthma-related ED visits (blue bars, left axis) and associated healthcare cost savings (purple line, right axis).

The economic impact of the modeled intervention was also substantial. With a median cost of $1,502 per asthma-related emergency department (ED) visit, the estimated healthcare savings totaled $3.19 million annually. Pediatric ED visit reductions contributed to $1.22 million, while adult reductions accounted for $1.97 million. Figure 3 depicts the distribution of healthcare savings across populations, emphasizing the economic benefits of targeted pollution reduction strategies.

Overall, the results of this study highlight the potential of a four-day workweek as an effective intervention for improving urban air quality, reducing asthma exacerbations, and alleviating economic burdens. The current study prioritizes NO₂ as a responsive and actionable air pollutant through an evidence-based, scalable framework that policy seeks to address traffic-related health and environmental challenges.

4. Discussion

The four-day workweek is gaining traction with a variety of socioeconomic benefits, including better work-life balance and increased productivity. Advocates highlight its potential to reduce stress, enhance job satisfaction, and improve overall well-being without adversely affecting economic performance [27, 28]. Trials in Iceland, Japan, and the United Kingdom have demonstrated that shorter workweeks can maintain or even improve productivity levels while reducing absenteeism and enhancing employee retention [29, 30]. From a societal perspective, a four-day workweek offers the potential to alleviate traffic congestion and commuting time, thereby improving quality of life and increasing leisure opportunities. This shift could also stimulate local economies, as workers might spend more on recreation and local businesses during extended weekends [31].

However, the four-day workweek is not without its challenges. One concern is work intensification, wherein employees may face increased workloads during shorter weeks, potentially leading to burnout [32]. This risk is particularly pronounced in industries where tasks are deadline-driven or reliant on client-facing services. Furthermore, certain sectors may struggle to adapt, particularly those that require continuous operations or high levels of service availability [33, 34]. From an economic perspective, skeptics caution that if productivity gains are not realized, sectors such as manufacturing or retail could face reduced output or increased labor costs [35].

The environmental impact of a four-day working week has, to date, not been fully explored but is emerging as a critical area of interest. Reducing the number of commuting days could significantly lower traffic volumes, decrease vehicular emissions, and improve urban air quality. Studies consistently show that vehicle emissions are a primary source of nitrogen dioxide (NO₂), a pollutant closely linked to traffic activity and known to contribute to adverse respiratory and cardiovascular health outcomes [36, 37]. Furthermore, fewer workdays may also reduce energy consumption in office buildings, offering secondary environmental benefits [38]. While the potential for air quality improvements is promising, behavioral changes, such as increased recreational travel during extended weekends, could offset some of these gains [39].

Our study estimates the potential public health and economic benefits of a four-day workweek based on its potential to decrease traffic-related NO₂ emissions, improve air quality, and prevent asthma-related ED visits. This weekend effect – where NO₂ levels are significantly lower due to reduced vehicular activity – suggests that extending weekends to 3 days could sustain these air quality improvements. These findings have implications for environmental science, public health, and the development of policy.

Among the three pollutants analyzed—NO₂, PM2.5, and AQI—only NO₂ showed significant changes between weekdays and weekends. NO₂ is a direct byproduct of vehicular emissions, making it highly sensitive to traffic patterns [18].   By contrast, PM2.5 and AQI are influenced by a range of sources, including industrial emissions, secondary aerosol formation, and regional atmospheric factors, which dilute the impact of local traffic changes [40, 41]. These results are in accordance with previous research, which considered NO₂ as an indicator pollutant of urban traffic-related emissions [42, 43]. Previous studies have indicated a high level of association between NO₂ exposure and health outcomes, including respiratory illnesses such as asthma exacerbations, reduced lung function, and hospital admissions [44]. A meta-analysis of NO₂ exposure studies estimated that for every 1 µg/m³ increase in NO₂, there is a 4% increase in asthma exacerbations– a relationship also found in the health impact modeling of this study [26]. Therefore, targeting NO₂ reduction has prime importance in traffic-related pollution control strategies.

The observed weekend effect on NO₂ levels aligns with existing research demonstrating reduced pollutant concentrations during periods of lower traffic [45]. Studies in London, for example, have shown that weekend NO₂ levels decrease by up to 20% compared to weekdays due to reduced vehicle usage [46]. Similar trends have been observed in other metropolitan areas, including New York City [47]. These findings suggest that structural changes to work schedules, such as a four-day workweek, may replicate these reductions on weekdays.

Traffic reduction policies are not a new concept; instead, low-emission zones (LEZs) and congestion pricing have already proven impactful across cities worldwide. For example, in London, LEZs led to reductions in NO₂, with improvements in both air quality and public health [22]. While these interventions require infrastructure modifications and enforcement mechanisms, the four-day workweek offers a simpler, behavior-driven approach leveraging existing societal structures.

Asthma disproportionately affects children and individuals with predisposed conditions, putting them particularly at risk of traffic-related pollutants such as NO₂ [48]. In this study, pediatric populations accounted for nearly 40% of the projected reduction in asthma-related emergency department (ED) visits under the four-day workweek intervention. Prior studies have shown that children bear a disproportionate share of the health burden due to exposure to traffic pollution, which is associated with stunted lung development and an increased risk of respiratory infections [49, 50]. These findings underscore the dual benefit of NO₂ reductions for both public health and equity, addressing the needs of vulnerable populations.

The reduction in asthma-related emergency department (ED) visits translated into significant economic savings. Using an average cost of $1,502 per asthma-related emergency department (ED) visit, this study estimated a savings of $3.19 million annually in healthcare expenditures. The cost estimate was derived from a peer-reviewed study that examined hospital charges for asthma patients across the U.S. [51]. However, other studies suggest that this figure may be conservative, as it does not account for indirect costs such as lost productivity, transportation, and long-term health complications [52, 53]. A 2016 analysis of the asthma burden in San Joaquin Valley, California, reported total direct and indirect costs exceeding $3,000 per ED visit when productivity losses were included, suggesting that the true total savings from this intervention may be significantly higher [54]. However, retrospective studies like this one often have limitations including challenges in data collection, various biases surrounding the study, and an inability to control for confounding variables. Additionally, this study focuses on only a single population, limiting the generalizability of the findings. It also does not account for those that may be remotely working from home and thus do not participate in the everyday commute.

5. Conclusion

This study demonstrates the potential of a four-day workweek as a public health intervention that is impactful in improving air quality, reducing respiratory health burdens, and alleviating economic pressures on healthcare systems. By modeling reductions in weekday vehicular traffic, the intervention resulted in significantly lower levels of NO₂. These reductions were associated with a 6.38% decrease in ED visits for asthma, equating to more than 2,100 fewer ED visits annually and healthcare savings of $3.19 million. The findings identify NO₂ as a particularly sensitive and actionable metric for traffic-related pollution control in ways distinct from other indices of interest, such as PM2.5 and AQI, which did not exhibit significant weekday-weekend differences.

The implications extend beyond asthma as NO₂ has well-documented effects in chronic obstructive pulmonary disease, cardiovascular disease, and even mortality [55, 56]. The public health implications of NO₂ reduction, therefore, are more far-reaching and could lead to lower healthcare costs related to long-term health conditions and improved population health. Public health policies have historically prioritized PM2.5 and composite air quality indices (AQI), yet this study underscores the importance of NO₂-specific strategies to address urban pollution more effectively. Policymakers should consider incorporating NO₂-focused interventions, such as traffic reduction programs and workweek restructuring, into broader environmental and public health frameworks.

A four-day workweek offers a scalable, behavior-driven solution that can be implemented with minimal infrastructural changes. Unlike resource-intensive strategies like low-emission zones or vehicle electrification, this intervention leverages existing societal structures to achieve measurable health benefits. By extending weekends, cities can reduce vehicular emissions, improve air quality, and simultaneously address broader urban challenges such as congestion, work-life balance, and productivity. These attributes align with sustainability goals, making the four-day workweek a viable urban intervention globally.

Future research should focus on validating these findings using real-world data from cities that are piloting four-day workweeks. Gaining more precise insights into the shifts in commuting and recreational activities, their interactions, and the consequences for air quality will be critical in further refining the intervention design. Full economic evaluations should also include indirect costs and benefits, such as increased productivity, reduced transportation costs, and long-term health outcomes, to fully capture the societal value of the intervention. Furthermore, NO₂ reduction and its interaction with other pollutants, such as ozone, can help in understanding the wide environmental impact caused by traffic-related interventions.

This study highlights the underexplored potential of structural shift in work patterns toward mitigating urban pollution and its health effects. A four-day workweek offers not only measurable benefits to respiratory health but also tangibly contributes to broader sustainability and social equity goals. Policymakers should consider both its direct and immediate impact in addressing a critical public health concern, as well as its longer-term role in nurturing healthier and more equitable urban environments.

Core Tip: This paper explores the viability of a four-day workweek, as its implementation could reduce the nitrogen dioxide emission by around 1.59 µg/m³ in Los Angeles County. The four-day workweek could also improve public health by potentially preventing over 2,100 asthma-related emergency department visits annually and have economic benefits by saving around $3.19 million in healthcare costs.

Acknowledgment

I would like to express my sincere gratitude for the invaluable support and cooperation provided by the staff, participants, and my co-authors/colleagues who contributed to this study.

Financial support and sponsorship

No funding sources.

Conflicts of interest

There are no conflicts of interest.

Ethical approval

The study was approved by the Institutional Ethics Committee.

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