Pollution's Impact: Cities' Future At Stake

Pollution is a pressing issue for cities around the world, with air pollution rising at an alarming rate and causing significant harm to both human health and the environment. As cities continue to grow, with increasing population density and demands, the problem of pollution becomes more acute. Poor air and water quality, insufficient water availability, waste disposal problems, and high energy consumption are all challenges that cities face. Air pollution, in particular, has far-reaching consequences, contributing to respiratory infections, heart disease, stroke, lung cancer, and even behavioural problems and increased crime rates. It is a major environmental risk factor for early death, with outdoor air pollution causing approximately 7 million premature deaths annually. Additionally, pollution impacts plant and insect life, disrupting ecosystems and threatening food production. Addressing pollution requires strong city planning, sustainable transport, efficient energy production, and effective waste management.

Air pollution impacts human health and behaviour

Air pollution is a major health risk, causing disease and premature death. It is the presence of contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities that can be harmful to human health. The primary pathway of exposure is through the respiratory tract, but some pollutants can enter the bloodstream and circulate throughout the body.

Health Impacts

Almost every organ in the body can be impacted by air pollution. The specific diseases most strongly linked to exposure to air pollution include respiratory infections, stroke, ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataract (household air pollution only). There is also evidence linking air pollution exposure to an increased risk of adverse pregnancy outcomes, diabetes, cognitive impairment, and neurological diseases.

Fine particulate matter (PM2.5) is the air pollutant driving the most significant health problems and premature mortality. Other dangerous pollutants include carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2) and sulphur dioxide (SO2).

Children, the elderly, and pregnant women are more susceptible to air pollution-related diseases. Genetics, comorbidities, nutrition, and sociodemographic factors also impact an individual's susceptibility to air pollution.

Behavioural Impacts

There is growing evidence that air pollution affects human behaviour, particularly in young people. Exposure to air pollutants has been linked to increased anxiety, which can lead to a rise in criminal or unethical behaviour. Studies have shown that cities with higher levels of air pollution have higher levels of crime, particularly petty crime.

One study concluded that higher levels of particulate matter pollution increase teenage delinquent behaviour in urban neighbourhoods. Another study of 9,360 US cities found that a 10-point raise in the air quality index (AQI) increases the crime rate by 0.9%.

Lead was removed from petrol in the USA in the 1970s due to concerns that vehicle emissions were contributing to behavioural problems, learning difficulties, and lowered IQ among children. Exposure to lead increases traits such as impulsiveness, aggression, and low IQ, which can influence criminal behaviour.

Pollution affects plants and insects

Pollution is defined as the introduction of human-made substances or natural substances released by humans, as well as forms of energy, into the environment. Insects and plants, like other living organisms, are affected by pollution.

Effects of Pollution on Insects

Insects are used to assess the effects of pollution as representatives of larger assemblages of organisms in communities and ecosystems. They are referred to as biomonitoring agents. The effects of pollution on insects occur at various scales, from biochemical effects at the molecular level to changes in insect populations and communities over time. Common pollutants that impact insects include pesticides, metals, organic compounds, industrial emissions, radiation, and habitat destruction.

Pollution can alter insect populations by decreasing species richness and evenness, with pollution-tolerant species replacing more sensitive ones. For example, sewage pollution in freshwater ecosystems can lead to a decline in the total number of insect species and an increase in tolerant organisms such as dronefly maggots and midge larvae.

Additionally, pollution can disrupt feeding habits. For instance, the removal of a riparian zone surrounding a stream can increase algae production, leading to an increase in grazing insects that feed on algae and a decrease in insects that depend on leaves. Air pollutants can also suppress parasites, leading to outbreaks of forest insect pests that are normally controlled by these parasites.

Effects of Pollution on Plants

Plants can be injured by exposure to high concentrations of air pollutants, and the severity of injury depends on factors such as the length of exposure, plant species, developmental stage, and environmental conditions. Local pollutants, emitted from a specific source, create well-defined zones of vegetation injury or contamination. Common local pollutants include sulfur dioxide, fluorides, ammonia, and particulate matter.

Ozone, a major component of oxidant smog, is produced by a reaction between nitrogen oxides and reactive hydrocarbons from automobile exhaust and fossil fuel combustion. Ozone injury to plants was first observed in Los Angeles in 1944 and has since been documented across North America. It causes necrotic lesions or yellowing of leaves, reduced growth, and even plant death.

Sulfur dioxide, released from coal-burning and petroleum combustion, enters leaves through microscopic openings called stomata. Acute exposure to high concentrations of sulfur dioxide causes bifacial lesions, while chronic exposure at sub-lethal concentrations leads to leaf yellowing or chlorosis.

Fluorides, released into the atmosphere from coal combustion and industrial processes, are absorbed by leaves and conducted towards the margins of broad leaves or the tips of monocotyledonous leaves. Fluoride injury appears as gray or light green lesions that turn reddish-brown over time, eventually leading to tissue necrosis.

Ammonia injury to vegetation has been observed following accidents involving ammonia fertilizers, releasing large amounts of ammonia into the atmosphere and causing severe damage to nearby plants. The injury appears as bleached, bifacial, necrotic lesions on leaves and can affect grasses and woody tissues.

Particulate matter, such as dust deposited on vegetation, can inhibit respiration and photosynthesis in leaves. It may also affect the effectiveness of pesticides and agricultural sprays. Additionally, the accumulation of alkaline dust in the soil can increase soil pH, impacting crop growth.

Urbanisation spurs poverty and environmental degradation

Urbanization spurs a unique set of issues for both humans and animals. The pull factors of cities, such as the promise of jobs and prosperity, have led to an ever-increasing global population shift towards urban areas. This shift exacerbates the two most pressing global issues: poverty and environmental degradation.

Intensive urban growth can lead to greater poverty, with local governments unable to provide services for all people. The urban poor often live in slums that are unregulated, congested, overcrowded, and positioned near open sewers and geographically dangerous areas. These factors lead to the spread of communicable and non-communicable diseases, pollution, poor nutrition, road traffic, and so on.

Urbanization also has a major negative impact on the nutritional health of poor populations. The urban poor lack nutritious diets due to limited financial resources and higher food costs in cities, leading to illness and poor absorption of nutrients. Environmental contamination further contributes to undernutrition, as street food is often prepared in unhygienic conditions.

In addition, populations in poor nations suffer from protein-energy malnutrition, with increased susceptibility to infection through micronutrient deficiency. Around 168 million children under five are estimated to be malnourished, with 76% living in Asia. At the same time, obesity is becoming an increasingly global problem, even in poor countries, due to a lack of physical space, sedentary work, and excessive energy intake.

Pollution is another major issue in urban environments. The World Health Organization estimated that 6.5 million people died as a consequence of indoor and outdoor air pollution, with 90% of these deaths occurring in low- and middle-income countries. Pollution from congested urban areas contributes to localized and global climate change and direct health problems, such as respiratory illnesses, cardiovascular diseases, and cancer, for both rich and poor residents.

To combat these issues, strong city planning and management will be essential as the world's urban areas continue to swell. Policies should aim to improve the socio-economic conditions of the urban poor, promote economic development and job creation, and involve the local community in local government. Additionally, reducing air pollution through upgraded energy use and alternative transport systems, as well as creating private-public partnerships to provide essential services, will be crucial.

Pollution increases the risk of environmental hazards

Pollution in cities is a pressing issue that poses significant risks to both human health and the environment. One of the most concerning aspects is the increased risk of environmental hazards that can have far-reaching consequences.

Urban areas, with their high population density and unique set of challenges, face amplified risks of environmental hazards due to pollution. One of the primary concerns is the increased risk of flash flooding. As cities expand and develop, natural absorption systems, such as urban tree cover, are often lost due to pollution and physical barriers. This loss of vegetation reduces the city's ability to absorb and manage excess water, contributing to flash flooding events.

In addition to flooding, pollution can also increase the risk of other environmental hazards. For example, high levels of air pollution can have a detrimental effect on plants and insects, as evidenced by research from the University of Sheffield. This, in turn, can disrupt ecosystems and have far-reaching consequences on the food chain. Insects play a crucial role in pollinating food crops, ensuring the survival of wildflowers, shrubs, and trees, and maintaining healthy soils. When pollution levels are high, the risk of environmental damage increases, threatening the delicate balance of urban ecosystems.

Furthermore, pollution in cities can also contribute to the loss of animal habitats and food sources. As cities expand, animals are inhibited by toxic substances, vehicles, and the loss of their natural environment. This can lead to a decline in animal populations and disrupt the ecological balance.

The impact of pollution on the environment is not limited to ecological damage. Pollution can also affect the climate and contribute to global warming. For example, nitrogen dioxide (NO2), a major component of smog, is produced by the burning of fossil fuels and is particularly prevalent in cities. NO2, along with other greenhouse gases, contributes to the warming of the planet and can exacerbate the impacts of climate change, such as extreme weather events.

To mitigate these risks, strong city planning and pollution reduction strategies are essential. This includes promoting economic development, creating private-public partnerships for waste disposal and housing, and incorporating the care of green spaces into urban planning. By addressing these issues, cities can reduce the risk of environmental hazards and create a more sustainable and resilient future.

Air pollution is a public health emergency

The impact of air pollution on human health is well-documented. Exposure to high levels of air pollutants raises the risk of respiratory infections, heart disease, stroke, lung cancer, pneumonia, neurological disorders, reproductive system issues, and dementia. Air pollution has also been linked to type 2 diabetes, obesity, systemic inflammation, and Alzheimer's disease. The International Agency for Research on Cancer has classified air pollution, particularly fine particulate matter (PM2.5), as a leading cause of cancer.

Children and adolescents are especially vulnerable to the effects of air pollution, as their bodies and immune systems are still developing. Air pollution damages health during childhood and increases the risk of diseases later in life. Older people and those with pre-existing health conditions are also more susceptible to the health impacts of air pollution. In addition, people of lower socioeconomic status are often more exposed to air pollution, as they are more likely to live near busy roads or industrial areas.

The sources of air pollution are varied and include household combustion devices, motor vehicles, industrial facilities, and forest fires. The major outdoor pollution sources include residential energy for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry. The combustion of fossil fuels contributes significantly to air pollution and climate change.

The good news is that there are effective strategies to reduce air pollution. Strong city planning and management are essential, including promoting sustainable ways of public transport, reducing the use of private cars, and improving energy efficiency in buildings. At the individual level, people can advocate for better air quality monitoring systems and put pressure on politicians and local governments to implement measures to reduce air pollution.

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