The case of Tehran's urban heat island, Iran: Impacts of urban 'lockdown' associated with the COVID-19 pandemic

The increasing expansion of urban environments with associated transformation of land-cover has led to the formation of urban heat islands (UHI) in many urbanized regions worldwide. COVID-19 related environmental impacts, through reduced urban activities, is worthy of investigation as it may demonstrate human capacity to manage UHI. We aim to establish the thermal impacts associated with COVID-19 induced urban 'lockdown' from 20 March to 20 April 2020 over Tehran. Areal changes in UHI are assessed through Classification and Regression Trees (CART), measured against background synoptic scale temperature changes over the years 1950-2020. Results indicate that monthly T_mean, T_max and T_min values during this time were considerably lower than long-term mean values for the reference period. Although the COVID-19 initiated shutdown led to an identifiable temperature anomaly, we demonstrate that this is not a product of upper atmospheric or synoptic conditions alone. We also show that the cooling effect over Tehran was not spatially uniform, which is likely due to the complexity of land uses such as industrial as opposed to residential. Our findings provide potentially valuable insights and implications for future management of urban heat islands during extreme heat waves that pose a serious threat to human health.

Urban morphology detection and it's linking with land surface temperature: A case study for Tehran Metropolis, Iran

Expansion of urban areas and alteration of natural land cover exacerbate the local climate change. To find out the effect of land cover changes on the local climate, in this study, the Local Climate Zone (LCZ) concept was utilized to detect urban morphology in Tehran Metropolis. LCZ and Land Surface Temperature (LST) can be identified and classified based on available remote sensing products. Firstly, LCZ maps of Tehran metropolis were extracted using Landsat imagery, and secondly, relationships between LCZ and LST were explored for three years (1990, 2004, and 2018). We found that Tehran urban structure has 13 LCZs based on imagery from Landsat 5 and 14 LCZs based on images for Landsat 7 and 8. Overall accuracy and kappa coefficient were estimated at 62% and 0.60, respectively. Results show that built-up classes including compact high-rise, compact mid-rise, and heavy industrial areas tended to increase the surface temperature, while except for bare land, all other land cover types tended to decrease the surface temperature. The findings also suggest that complementary optical and thermal remote sensing data, such as the combination of OLI with TIRS imageries, were sufficient for supervised LCZ and LST classification in a semi-arid region of Tehran metropolis.

Achievements and future path of Tehran municipality in urban health domain: An Iranian experience

BACKGROUND

According to national laws and world experiences; provision, maintenance, and improving citizens' health are considered to be the essential functions of municipalities as a "social institute". In order to equitably promote health conditions at urban level, particularly in marginal areas, since 2004 targeted efforts have been implemented in the municipality of Tehran metropolis. This study was intended to identify and analyze these targeted measures and tries to analyze health interventions in a conceptual framework and propose a future path.

METHODS

This is a qualitative study with content analysis approach. Reviewing documents and structured interviews with national health policy making and planning experts and executive managers of 22-region municipalities of Tehran metropolis were used to collect data. The data were analyzed on the basis of conceptual framework prepared for urban health in 4 domains including municipal interventions, goal achievements, drivers and obstacles of success, and the way forward.

RESULTS

From the viewpoint of interviewees, these new health actions of Tehran municipality are more based on public participation and the municipality was able to prioritize health issue in the programs and policies of Tehran city council. Tehran municipality has accomplished three types of interventions to improve health, which in orders of magnitude are: facilitative, promotional, and mandatory interventions. Development and institutionalization of public participation is the greatest achievement in health-oriented actions; and expansion of environmental and physical health-oriented facilities and promoting a healthy lifestyle are next in ranks.

CONCLUSION

Since management alterations seriously challenges institutionalization of actions and innovations especially in the developing countries, it is suggested that mayors of metropolitan cities like Tehran document and review municipal health measures as soon as possible and while eliminating overlapping of interventions with other sectors, design and approve the charter of "health promoting municipality". The most important role of municipalities in this charter would be coordinating health improvement of citizens. This charter, when approved as a national policy could be used for other cities too.