The environment plays a crucial role in people’s physical, mental and social well-being. Every one of us is sustained by various kinds of environmental resources such as food, materials, and energy that are harvested or otherwise extracted from the environment. Our need for those resources is absolute and we cannot survive without them.
Although the environment sustains human life, it can also influence the health of a population. The environment in which we live greatly affects our health. The interaction between human health and the environment has been extensively studied and environmental risks have been proven to significantly impact human health, either directly by exposing people to harmful agents, or indirectly, by disrupting life-sustaining ecosystems (WHO, 2009). Many factors combine together to affect the health of individuals and communities. Whether people are healthy or not, is determined by their circumstances and environment. To a large extent, factors such as where we live, the state of our environment…have considerable impacts on health, whereas the more commonly considered factors such as access and use of health care services often have less of an impact (WHO, 2014a).
The environment affects our health in a variety of ways. The household, workplace and outdoor environments can pose many health hazards from contamination of the air we breathe, the water we drink and the food we eat, to the risk of accidental injury from vehicles or unsafe housing. (Cairncross et al., 2008 P. 7, cited in: WHO, 2014a). Up to one-fifth of the total disease burden in developing countries may be associated with environmental risk factors (Irish Aid 8, 2008). A global assessment by WHO in 2016 estimated that 24% of the global disease burden and 23% of all deaths were attributed to modifiable environmental factors, including physical, chemical, and biological hazards to human health (Prüss-Ustün et al., 2016 cited in: Joubert et al., 2020). In 2012, an estimated 12.6 million deaths globally were attributable to the environment, 23 per cent of all deaths worldwide (Mc Glade et al., 2016).
Humans share an interactive relationship with the environment. Biological, physical, chemical, biomechanical, and psychosocial factors in the environment affect humans, who in turn exert an impact on the environment. Potentially, this interactive relationship exposes humans to environmental health hazards. These include any environmental situation or factor that can lead to disease, injury, or death.
Air pollution is the world’s largest single environmental risk to health. Some 7 million people across the world die each year as a result of everyday exposure to poor air quality (Greater London Authority, 2013). In urban areas, most air pollution comes from human-made sources. Such sources can be classified as either mobile (cars, trucks, air planes, marine engines, etc.) or point source factories, electric power plants, etc.). Road traffic constitutes the major source of air pollution (Pénard-Morand and Annesi-Maesano, 2004, P. 109).
Another environmental risk to health is waterborne diseases that cause 1.5 million deaths every year (WHO 2014b). More than half of that burden, or 842 000 deaths per year, are attributable to unsafe water supply and lack of sanitation and hygiene. Surface water flooding describes flooding on the land surface from sewers, drains, groundwater and runoff from land after a heavy rainfall event. Its events are difficult to predict, but can cause significant disruptions to local populations and to health and other services (Surface Water Management Plan, 2010). Groundwaters all around the world are increasingly affected by salinization, pollution from nitrates, organic micropollutants and trace elements (Chapman, 1992). In many cities, groundwaters are used for washing and even for drinking.
Solid waste generally has a high content of organic material, thus providing breeding grounds for micro-organisms and disease-bearing insects. The organization and environmental behavior of waste removal is problematic in the way that the individual incentive for disposing of waste in a sanitary way is limited.
Motorized vehicles constitute environmental problems in as much as they contribute to traffic accidents, air and noise pollution and in this way, they are a risk to human health. Road-traffic accidents are the most important cause of unintentional injury. Regarding air pollution, the emissions from transport are released close to the ground where human exposure is higher, and these may, just as indoor air pollutants, have a disproportionately high impact on human health (KjellÈn, 2001: 28). Furthermore, in urban areas, the largest source of noise is traffic-induced noise, which accounts for 80% of all communal noise sources. Traffic noise caused by road traffic is the most common type of noise in urban areas and as such poses a serious health problem (Sanja Grubesa, and Suhanek, 2020).
Settlements adjacent to farms and gardens can also be in risk from unintentional spraying. Pesticides may also affect water supplies. The major threat posed by pesticides in developing countries is acute poisoning, estimated at 3 million severe incidents per year, with some 220,000 deaths (Hogstedt and Pieris, 2000).
Although, some rivers run across cities, provide attractive landscape and recreational services, they can affect the health of users or people living near them. Along rivers, animals such as dogs, cats, mice, and snakes may be encountered and insects such as flies, mosquitoes, bees, tarantulas, scorpions are usually more abundant than places far from rivers (McCabe, 2011). Surface water pollution can however be a direct means of disease transmission for people working in or near the water. In many rivers, pathogens, decomposable organic matter, organic micropollutants, suspended solids or trace metals are becoming increasingly problematic swimmers or children playing by the shore (WHO, 2016).
Unlike the mentioned health risk factors, accessible green space has long been recognized as a wider environmental determinant of good health. Wide ranging research shows strong evidence that outdoor spaces have a beneficial impact on both physical and mental well-being (Greater London Authority, 2013).
Environmental issues, some of them mentioned, affect our health and have been one of the most significant triggers in the increasing awareness of the need for better environmental management. This paper aimed to investigate environmental health indicators and spatial inequality of environmental health in Hashtpar city, Iran. Due to several reasons, investigating the subject in the study area is important. The first is the diversity of geographical factors thorough out the city with an area of only less than 1380 ha: a river flowing across the city, a main crowded regional transportation axis crossing it, and the city is surrounded by farms, gardens and forests. The second one is unplanned growth of the city in recent decades that cause to appear informal settlements in part of the city, and the third reason relates to its climate. In Caspian coastal lands of Iran, warm or temperate and humid climate, high population density and paddy fields and gardens, have caused an abundance of insects, animals and disease carriers that threaten human health.