Human Health: Pollution's Impact And Common Culprits

Air pollution 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. It is the single largest environmental health risk in Europe and a major cause of premature death and disease worldwide. Fine particulate matter (PM2.5) is the air pollutant driving the most significant health problems, including respiratory issues, heart disease, stroke, lung cancer, and even cerebral palsy in children. In 2021, 97% of the urban population was exposed to concentrations of fine particulate matter above the health-based guideline level set by the World Health Organization.

Fine particulate matter (PM2.5)

The health effects of PM2.5 exposure include oxidative stress and inflammation in human cells, which have been linked to chronic diseases and cancer. Short-term exposure to high levels of PM2.5 can lead to reduced lung function, respiratory infections, and aggravated asthma. Long-term exposure increases the risk of stroke, heart disease, chronic obstructive pulmonary disease, and lung cancer. PM2.5 has also been associated with an increased risk of adverse pregnancy outcomes, such as low birth weight and pre-term birth.

In children, exposure to PM2.5, even at relatively low levels, may alter the size of their developing brains, increasing the risk for cognitive and emotional problems later in life. Prenatal PM2.5 exposure has been linked to an increased risk of cerebral palsy and neurobehavioral problems, such as ADHD.

PM2.5 is a significant contributor to air pollution and its associated health effects. In the European Union, ambient air pollution primarily due to PM2.5 is responsible for approximately 659,000 deaths per year, with 50-80% of these deaths attributed to cardiovascular events. In the United States, PM2.5 accounts for most of the health effects due to air pollution.

To reduce exposure to PM2.5, various strategies can be implemented, such as using high-efficiency particulate air (HEPA) filtration, creating vegetation barriers, and improving urban design with green spaces. These measures can help mitigate the health risks associated with fine particulate matter pollution.

Ozone

Children are at the greatest risk from ozone exposure because their lungs are still developing, and they are more likely to be active outdoors when ozone levels are high, increasing their exposure. Children are also more susceptible to asthma, which can be aggravated by ozone. Some studies suggest that women may face a higher respiratory health risk from ozone exposure.

Breathing in other pollutants in the air may also make the lungs more responsive to ozone. For example, research warns that breathing sulfur dioxide and nitrogen oxide can make the lungs react more strongly than just breathing ozone alone.

Carbon monoxide

Air pollution is defined as the presence of one or more contaminants in the atmosphere, including dust, fumes, gas, mist, odour, smoke, or vapour, in quantities that can be harmful to human health. While air pollution as a whole has been associated with a range of adverse health effects, carbon monoxide (CO) is a specific pollutant that poses significant risks.

One of the primary dangers of carbon monoxide is its ability to bind to haemoglobin in the blood, forming carboxyhaemoglobin (COHb). This binding reduces the blood's oxygen-carrying capacity, leading to inadequate oxygen delivery to the body's organs, particularly the brain. Common symptoms of carbon monoxide exposure include fatigue, headaches, confusion, and dizziness. In more severe cases, CO exposure can result in chest pain, decreased exercise tolerance, and even death. Over 400 people in the United States die annually from CO poisoning, with a significant number of cases occurring during the cold season due to the increased use of improperly vented space heaters.

Individuals with underlying cardiovascular disease are particularly vulnerable to the effects of carbon monoxide. Studies have shown that acute exposure to carbon monoxide exacerbates cardiovascular conditions, including myocardial ischemia and cardiac arrhythmias. Even in healthy individuals, acute exposure to high concentrations of carbon monoxide can trigger compensatory cardiovascular responses. Additionally, unborn babies, infants, the elderly, and individuals with anaemia or respiratory diseases are at an increased risk of experiencing health effects from elevated levels of carbon monoxide exposure.

Nitrogen dioxide

Air pollution is defined as the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities and durations that can be harmful to human health. One of the main pollutants is nitrogen dioxide (NO2), a pungent gas composed of nitrogen and oxygen. NO2 is formed when fossil fuels such as coal, oil, gas or diesel are burned at high temperatures. It is also produced during the burning of natural gas (methane), both outdoors and indoors.

NO2 is a highly reactive gas and a member of the nitrogen oxides (NOx) family, which also includes nitric acid and nitrous acid. It is a significant air pollutant, contributing to particle pollution and the formation of other air pollutants, including ozone (O3) and fine particles. NO2 is a key agent in the formation of toxic substances, such as peroxyacetyl nitrate, nitrosamines, and nitro-polycyclic aromatic hydrocarbons (nitro-PAHs).

In addition to respiratory issues, NO2 has been linked to adverse health outcomes in asthmatics at lower concentrations. It is also associated with an increased risk of cerebral palsy in children. Studies have found prenatal NO2 exposure to be linked to brain development effects, slower processing speed, and neurobehavioural problems in urban youth.

Regulators have focused on reducing NO2 emissions, and standards have been set to limit its levels in outdoor air. As a result, emissions have decreased over the years, and air quality has improved. However, many people still breathe unhealthy levels of NO2, particularly in large urban areas and near heavily travelled roadways.

Sulphur dioxide

Air pollution is defined as the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities and durations that can be harmful to human health. While air pollution as a whole is a significant concern for human health, sulphur dioxide (SO2) is one of the pollutants with the strongest evidence for public health impacts.

The primary pathway of exposure to sulphur dioxide is through the respiratory tract. SO2 causes a range of harmful effects on the lungs, including wheezing, shortness of breath, chest tightness, and other respiratory problems, especially during exercise or physical activity. Rapid breathing during exercise facilitates the entry of SO2 into the lower respiratory tract, as does breathing through the mouth. Long-term exposure to high levels of SO2 increases respiratory symptoms and impairs lung function, while short-term exposure to peak levels can cause breathing difficulties, especially for people with asthma.

Children, the elderly, and people with asthma are at a particularly high risk of experiencing adverse health effects from sulphur dioxide exposure. Studies have shown that exposure to SO2 increases the risk of hospital admissions or emergency room visits, especially among these vulnerable populations.

While SO2 levels have improved over time due to policies promoting cleaner fuels and pollution controls on power plants, it remains a significant health concern. Unhealthy levels of SO2 can still occur due to equipment malfunction or during the starting or shutting down of polluting sources such as power plants.

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