1. Introduction
Physical inactivity is a pressing global health concern, exacerbated in modern urban environments by sedentary lifestyles. In Iran, it is a major risk factor for prevalent non-communicable diseases like heart disease and diabetes. Concurrently, rapid urbanization and growing dependence on private vehicles have worsened environmental issues and diminished active transportation. Public transit systems, notably metros, offer a sustainable alternative that can alleviate congestion, improve air quality, and inherently promote physical activity by requiring walking for access and egress. Despite these potential benefits, the integration of health impact assessments into transport planning is often overlooked. This study addresses this gap by conducting a health economic evaluation of the Dowlat Abad Metro Station in Tehran, inaugurated in 2019. The primary aim is to quantify the health benefits, specifically in terms of prevented premature deaths and associated economic savings, arising from the increased physical activity facilitated by the station.
2. Theoretical Framework
This research is grounded in the methodology of Health Impact Assessment (HIA) and utilizes the World Health Organization's Health Economic Assessment Tool (HEAT) for walking and cycling(Kahlmeier et al., 2023). The theoretical basis is supported by robust epidemiological evidence establishing a continuous, dose-response relationship between physical activity and health; higher activity levels correlate with a reduced risk of all-cause mortality and diseases such as cardiovascular conditions. The study draws on international literature confirming that proximity to public transport, especially rail-based metros, is inversely associated with obesity rates, primarily due to the integration of walking into daily commutes. For economic valuation, the HEAT framework primarily employs the Value of a Statistical Life (VSL) approach, which estimates the societal economic value placed on reducing the risk of premature death.
3. Methodology
The study applied the WHO's HEAT methodology within the context of Tehran. The standard HIA process—comprising screening, scoping, appraisal, and reporting—was followed. Data were collected via a survey of 213 users of the Dowlat Abad Metro Station to capture travel patterns, including walking times to/from the station, trip frequency, and socio-demographic data. The core analysis calculated avoided premature deaths attributable to the metro-induced physical activity. Key parameters included:
(1) Physical Activity Volume: Based on average walking times of 11-15 minutes (access) and 5-10 minutes (egress), converted into Metabolic Equivalent of Task (MET) expenditure;
(2) Relative Risk (RR): A value of 0.81 for 660 MET-minutes/week was used to link activity to mortality risk reduction;
(3) Population Attributable Fraction (PAF): Calculated as PAF = (RR-1)/RR to determine the fraction of preventable deaths;
(4) Avoided Mortality (E): Estimated using E = PAF × B × P, where B is Tehran's baseline mortality rate and P is the exposed population;
(5) Economic Valuation: Benefits were monetized using both the official Iranian "Diyah" (blood money) and Iran-specific VSL estimates.
4. Results and Discussion
Survey findings indicated the station is mainly used by a young, educated population for work and study, with most users walking to and from it. The health appraisal revealed significant outcomes: the station's use prevents an estimated 68 premature deaths annually, equating to 1,020.6 Years of Life Lost (YLL) prevented (range: 719.4–1,321.8 YLL). Economically, using the "Diyah" value (1.2 billion tomans per life) yielded annual savings of 1,632,960 million tomans. A more precise analysis using Iran-specific VSL data estimated savings of 452 billion tomans per year. These results align with global studies using HEAT, affirming that the health gains from active travel outweigh risks like air pollution. They underscore that metro investments are not merely transport solutions but also crucial public health interventions. The discussion notes that the metro's impact is mediated by local factors, such as the quality of the pedestrian environment around stations. While the metro expands "activity spaces," maximizing its health potential requires supportive urban design, including safe pathways for the "last mile" of the journey.
5. Conclusion
This study demonstrates that the Dowlat Abad Metro Station has yielded substantial health and economic benefits for Tehran by promoting physical activity. The prevention of dozens of premature deaths and the generation of significant financial savings highlight the important co-benefits of investing in sustainable public transport infrastructure. The research underscores the necessity of integrating health considerations into urban and transport policy from the outset, advocating for a move beyond sectoral silos. It concludes that while metro development is a necessary step for improving population health, it is not sufficient on its own. To fully realize its potential, it must be coupled with complementary measures such as creating safe pedestrian and cycling infrastructure and promoting mixed land use. Future research should conduct prospective HIAs before project implementation and utilize longitudinal designs and localized data to enhance the accuracy of impact assessments.


Kahlmeier, S., Cavill, N., Thondoo, M., Rutter, H., De Sa, T. H., Racioppi, F., & Gotschi, T. (2023). The Health Economic Assessment Tool (HEAT) for walking and cycling-experiences from 10 years of application of a health impact assessment tool in policy and practice. Frontiers in Sports and Active Living, 5, 1146761.