Ahmad Maghrabi

The outbreak of the COVID-19 pandemic has emerged as a serious public health threat and has had a tremendous impact on all spheres of the environment. The air quality across the world improved because of COVID-19 lockdowns. Since the outbreak of COVID-19, large numbers of studies have been carried out on the impact of lockdowns on air quality around the world, but no studies have been carried out on the systematic review on the impact of lockdowns on air quality. This study aims to systematically assess the bibliographic review on the impact of lockdowns on air quality around the globe. A total of 237 studies were identified after rigorous review, and 144 studies met the criteria for the review. The literature was surveyed from Scopus, Google Scholar, PubMed, Web of Science, and the Google search engine. The results reveal that (i) most of the studies were carried out on Asia (about 65%), followed by Europe (18%), North America (6%), South America (5%), and Africa (3%); (ii) in the case of countries, the highest number of studies was performed on India (29%), followed by China (23%), the U.S. (5%), the UK (4%), and Italy; (iii) more than 60% of the studies included NO₂ for study, followed by PM_2.5 (about 50%), PM₁₀, SO₂, and CO; (iv) most of the studies were published by Science of the Total Environment (29%), followed by Aerosol and Air Quality Research (23%), Air Quality, Atmosphere & Health (9%), and Environmental Pollution (5%); (v) the studies reveal that there were significant improvements in air quality during lockdowns in comparison with previous time periods. Thus, this diversified study conducted on the impact of lockdowns on air quality will surely assist in identifying any gaps, as it outlines the insights of the current scientific research.

The review and assessment of urban greening patterns play a crucial role in sustainable urban planning and green spaces (GSs) management, helping to improve human well-being. In recent years, various methods and strategies were applied to examine the relationship between GSs and environmental sustainability, but so far, no studies on systematic review and empirical assessments were carried out in Saudi Arabian context. Thus, a comprehensive review and assessment of current GSs patterns and planning strategies are important for achieving urban environmental sustainability. This study aims to assess spatial pattern of GSs across the cities and a bibliographic review on the urban greening strategies in the Saudi context. These six urban strategies were further supported from empirical evidence on Saudi cities. Geographical information system (GIS) techniques and questionnaire surveys were performed for spatial mapping of GSs and the perceived role of GSs strategies of the respondent to environmental sustainability across cities. The findings showed that (i) highest PCGS was reported from Dammam (5.4 m²) followed by Riyadh (1.18 m²), and Jeddah (0.5 m²); (ii) most of the respondents use GSs for picnic (59%), mental well-being (53%), and physical activities (47%), respectively; (iii) GSs play a significant role for local climate regulation such as temperature control (78%) and UHI reduction (81%), and GSs provide thermal comfort (84%), respectively; and (iv) 40% respondents do not use GSs due to the lack of availability, accessibility, design, management, and safety of GSs. Thus, such findings of the study surely assist planners and policy makers to understand and implement the suggested GSs strategies to meet the satisfaction level of the respondents as well as to manage GSs at neighborhood and city level for urban environmental sustainability.

Green spaces (GSs) are significant, nature-based solutions to climate change and have immense potential to reduce vulnerability to heat waves while enhancing the resilience of urban areas in the light of climate change. However, in the Saudi context, the availability of GSs across cities and their perceived role in climate change mitigations and adaptation strategies remain unexplored. This study aimed to examine the per capita availability of GSs in the Jeddah megacity in Saudi Arabia, and their role in climate change mitigation and adaptation strategies. This study assessed the per capita availability of GS in Jeddah city using GIS techniques, and a questionnaire survey (online and an onsite) was conducted to assess the GSs users’ perception of the role of GSs on climate change mitigation and adaptation strategies. Non-parametric tests were also used to find differences in roles based on socio-demographic attributes. The findings of the study revealed that: (i) the per capita availability of GS in Jeddah is relatively low in comparison to international organization recommendations (such as World Health Organization and European Union). As per the survey result, it was reported that GSs play crucial role for climate change mitigation such as temperature regulation, reduction in heat stress, enhancement outdoor thermal comfort, and the maintenance of air quality. More than 85% of the total respondents agreed with the very high importance of GSs for climate change mitigation. More than 80% of respondents in the city highly agreed with climate change adaptation strategies such as the enhancement of accessibility to GSs, ecosystem-based protection of GSs, and the improvement of per capita availability of GSs. The findings of the study will be very helpful to planners and policymakers in implementing nature-based solutions to reduce vulnerability to climate change in Jeddah city, and particularly other cities in a desert environment.

Public open spaces services have been shown to be profoundly affected by rapid urbanization and environmental changes, and in turn, they have influenced socio-cultural relationships and human well-being. However, the impact of these changes on public open space services (POSS) remains unexplored, particularly in the Saudi Arabian context. This study examines the socio-cultural influence of POSS on the King Abdulaziz University campus, Jeddah, Saudi Arabia and the impact of these services on well-being. A field survey and questionnaire were used to collect data. Non-parametric tests (Kruskal–Wallis and Mann–Whitney tests) were used to find significant differences in the importance of POSS as perceived by stakeholders based on socio-demographic attributes. Factor analysis was performed for 14 POSS to identify those that are most important. The study showed that (i) university stakeholders are closely linked to services provided by public open spaces (POS) and dependent on POSS, (ii) there were significant differences in the perceived importance of POSS according to gender, age, and social groups, and (iii) 70 to 90% of stakeholders reported POSS as having a positive impact on well-being. Thus, the findings will help design and plan POSS to meet the needs of society and promote well-being.

Urban Heat Islands (UHIs) and Urban Cool Islands (UCIs) can be measured by means of in situ measurements and interpolation methods, which often require densely distributed networks of sensors and can be time-consuming, expensive and in many cases infeasible. The use of satellite data to estimate Land Surface Temperature (LST) and spectral indices such as the Normalized Difference Vegetation Index (NDVI) has emerged in the last decade as a promising technique to map Surface Urban Heat Islands (SUHIs), primarily at large geographical scales. Furthermore, thermal comfort, the subjective perception and experience of humans of micro-climates, is also an important component of UHIs. It remains unanswered whether LST can be used to predict thermal comfort. The objective of this study is to evaluate the accuracy of remotely sensed data, including a derived LST, at a small geographical scale, in the case study of King Abdulaziz University (KAU) campus (Jeddah, Saudi Arabia) and four surrounding neighborhoods. We evaluate the potential use of LST estimates as proxy for air temperature (T_air) and thermal comfort. We estimate LST based on Landsat-8 measurements, T_air and other climatological parameters by means of in situ measurements and subjective thermal comfort by means of a Physiological Equivalent Temperature (PET) model. We find a significant correlation (r = 0.45, p < 0.001) between LST and mean T_air and the compatibility of LST and T_air as equivalent measures using Bland-Altman analysis. We evaluate several models with LST, NDVI, and Normalized Difference Built-up Index (NDBI) as data inputs to proxy T_air and find that they achieve error rates across metrics that are two orders of magnitude below that of a comparison with LST and T_air alone. We also find that, using only remotely sensed data, including LST, NDVI, and NDBI, random forest classifiers can detect sites with “very hot” classification of thermal comfort nearly as effectively as estimates using in situ data, with one such model attaining an F1 score of 0.65. This study demonstrates the potential use of remotely sensed measurements to infer the Physiological Equivalent Temperature (PET) and subjective thermal comfort at small geographical scales as well as the impacts of land cover and land use characteristics on UHI and UCI. Such insights are fundamental for sustainable urban planning and would contribute enormously to urban planning that considers people’s well-being and comfort.

Public open spaces (POSs) provide multiple services (such as facilities for physical activities and social interactions) to local people, and these services are important for the well-being of society and for improving the quality of life. Extensive research on POSs has been carried out in developed countries (such as the US and Australia, as well as European countries including Spain, France, and Germany). However, POSs in the Saudi Arabian context remain unexplored. This study aims to examine the importance and performance of public open spaces on King Abdulaziz University (KAU) campus, Jeddah city, Saudi Arabia, using importance-performance analysis (IPA). One-way ANOVA and Kruskal–Wallis tests were performed to identify differences in the importance and performance of POSs. It was observed that there are significant differences between the importance and performance of public open spaces on the KAU campus, as perceived by stakeholders. Therefore, this study may be helpful in understanding the importance and performance of public open spaces, allowing spaces to be prioritized to improve management and restore open spaces to achieve environmental sustainability at a local scale. In addition, this study suggests that decision-makers involved in campus planning should consider the contribution of public open spaces to education, recreation, and the environment, at the campus planning stage.

Public open spaces (POS) have an essential positive impact on cities and their residents. These spaces play a critical role in enhancing users’ physical, mental, and social wellbeing. In addition, POS improve city resilience and economic value, and act as part of the city’s visual amenities. The Kingdom of Saudi Arabia is taking many approaches to enhance quality of life in all its cities through initiatives such as increasing the POS area per capita. Several studies have examined the importance of the accessibility of POS in addressing users’ needs. In this study, we measured the per capita area and accessibility of POS in the three megacities Riyadh, Dammam, and Jeddah. We also collected data on user preferences for the use of POS through semi-structured interviews, observations, and an online questionnaire. This study suggests that the country needs to establish its own POS planning approach based on users’ desires and behaviors when using POS, as well as the country’s social characteristics, and to depend not only on standard international planning approaches. The paper recommends considering the possibility of increasing POS by creating typologies of these spaces based on each city’s landscape characteristics. This proposal will have a major impact on city planning and design in Saudi Arabia. In addition, it will make the Saudi cities livable and have a positive impact on the physical, mental, and social wellbeing of the population.