# A Comprehensive Survey on the Societal Aspects of Smart Cities
## 2 Smart Cities Dimensions
### Smart Environment  
One of the key motivators for implementing smart cities is the environment. Urban populations have been steadily increasing throughout the twentieth century. In 2010, almost 52 percent of the world's population resided in urban areas, and this number is predicted to rise to over 68 percent of the population by 2050 [105]. Therefore, urban areas are responsible for 70 percent of the world's carbon emissions [106; 107] and will be severely affected by the effects of climate change. In fact, without even considering the knock-on effects of climate change, cities are at direct risk of destruction by the rising sea levels since most cities were built on or near coasts or rivers. Therefore, cities should improve their infrastructure by implementing smart technologies such as smart street lighting that adjusts to light conditions to curtail waste, smart meters for energy and water, sensors to detect leaks, smart irrigation, smart bins that notify when they are full, and more [108; 109; 110]. In the context of smart cities, the smart environment dimension includes the implementation of new services to turn cities more sustainable with healthier populations while guaranteeing economic development without sacrificing the environment [111]. For instance, air pollution has a significant impact on the health conditions of the cities' inhabitants, reducing their life expectancy and their quality of life. Systems exist that allow for accurate monitoring of air quality, which enable authorities to enact measures to curtail pollution sources [112; 113]. Additionally, one of the ways for a city to increase its environmental sustainability is by upgrading its electrical grid to a smart grid. Smart grids are focused on the use of non-polluting, less environmentally impactful, and renewable energies and aim to maximize efficiency by coordinating the production and use of stored energy to meet consumer demand, allowing for the integration of both centralized and distributed energy production grids [114; 115]. Considering the cities' surrounding environments, it is important to safeguard the linking of remote areas to the national energy grid, both to provide electrical power to remote villages and to harness remote, but high-energy production locations (e.g., mountain wind farms, island wave generators, or desert solar farms). Systems exist for local energy generation as an alternative or backup to the power grid in case of unexpected occurrences, which may take time to repair due to remoteness and low priority [116; 117]. These, and larger energy generation systems, can be monitored using IoT, resulting in better efficiency, lower costs, and better information availability despite remoteness [118; 119]. In turn, water management services require the monitoring of drinking water quality from local sources (e.g., artesian wells or communal fountains), rivers for pollutants, and flood warnings. Sensing systems are available for remote water monitoring in both large bodies of water (e.g., rivers, lakes, or dams) and smaller ones (e.g., wells or water tanks) [120; 121]. Moreover, smart environment technologies also include agricultural management of land and animals to maximize production without depleting natural resources and to prevent encroachment on natural habitats and wildlife. There are management systems that utilize IoT to improve or perform various tasks (e.g., weeding, irrigation, or monitoring of soil conditions), which help to increase yields, reduce costs and improve the sustainability of agriculture [122]. Possible examples include systems to manage irrigation and decrease waste, as agriculture is the biggest user of freshwater globally [123; 124], or systems to monitor wildlife both to minimize damage to agriculture caused by wildlife and to reduce human impact on wildlife [125; 126]. Additionally, heavily forested areas are more susceptible to fires, which can be difficult to detect and extinguish before reaching dangerous proportions due their remote and inaccessible locations.