Air Pollution: Harmful Impact On Human Health

Noise pollution is a growing problem across the globe, and its impact on human health is often underestimated. While air pollution is considered the environmental exposure that is most harmful to public health, noise pollution is a close second. This is a concern as noise pollution affects human health in several ways, including hearing loss, stress, high blood pressure, cardiovascular disease, and sleep disturbances. In addition, the impact of noise pollution on mental health and well-being cannot be overlooked, as it can cause annoyance, cognitive impairment, and negative effects on the metabolic system. With urban growth and increased mobility demand, it is projected that the number of people exposed to harmful noise levels will continue to rise, making it essential to address this issue through combined strategies and noise mitigation measures.

Cardiovascular and metabolic issues

Air pollution and noise pollution have been found to have significant adverse effects on human health. While noise pollution has been shown to cause annoyance, sleep disturbances, and negative effects on cardiovascular and metabolic systems, air pollution has been linked to more premature deaths. However, noise pollution also impacts quality of life and mental health.

Air pollution has been linked to an increased risk of cardiovascular issues. Fine particulate matter, with diameters less than 2.5 µm or PM2.5, is a major contributor to this risk. These particles can be inhaled and are small enough to penetrate deep into the cardiovascular system, causing localized endothelial dysfunction and systemic inflammation. This, in turn, can lead to oxidative stress, platelet activation, increased arterial inflammation, and cellular signaling abnormalities. The inflammation activates pro-thrombotic pathways, the hypothalamic-pituitary-adrenal axis, and causes autonomic dysfunction, which can lead to hypertension, atherothrombosis, altered glucose metabolism, and plaque instability. These issues can ultimately result in adverse cardiovascular outcomes such as myocardial infarction, arrhythmias, and heart failure.

Additionally, air pollution has been found to exacerbate existing cardiovascular conditions and increase the risk of related heart attacks and death. People with underlying cardiovascular diseases, such as ischemic heart disease or heart failure, or those who have previously experienced cardiovascular events like myocardial infarction or stroke, are particularly vulnerable to the effects of air pollution. Exposure to smoke from wildland fires, which includes wildfires and prescribed fires, has also been linked to a variety of adverse health effects, especially for those with pre-existing heart conditions.

Noise pollution has also been associated with cardiovascular and metabolic issues. Long-term exposure to noise can contribute to 48,000 new cases of ischaemic heart disease annually, along with 12,000 premature deaths. It can also cause high blood pressure, which is a traditional risk factor for cardiovascular disease.

Sleep disturbances

Environmental noise, especially from transportation, is a significant cause of sleep disturbances. This can lead to insomnia, daytime sleepiness, and tiredness. In addition, the stress caused by noise can have a negative impact on sleep quality.

Noise pollution can trigger a fight-or-flight response in the body, releasing stress hormones that affect blood pressure and heart rate. This can lead to increased cardiovascular morbidity and a range of negative health outcomes, including cardiometabolic, psychiatric, and social issues. Environmental noise has been linked to an increased risk of heart disease, cognitive impairment, depression, and anxiety.

Studies have shown that long-term exposure to noise can cause sleep disturbances, negatively affecting the cardiovascular and metabolic systems. It can also lead to measurable biological changes, such as increased stress levels, and can impact sleep architecture and subjective sleep quality. These effects can be seen in both adults and children, with 6.5 million people suffering from chronic high sleep disturbance due to noise pollution.

Noise-induced sleep disturbances are a growing problem, with road traffic noise being a major environmental concern for millions of people in Europe. Aircraft noise is also a significant source of sleep disruption, affecting the health and well-being of those living near airports. In addition, noise from construction, leaf blowers, and drones can contribute to sleep disturbances.

To mitigate the impact of noise pollution on sleep, it is essential to prioritize noise reduction strategies and public health initiatives. This includes implementing combined strategies to address both noise and air pollution from traffic, as well as technological improvements, ambitious noise policies, and better urban and infrastructure planning. By addressing noise pollution, we can improve sleep quality and overall health outcomes for individuals affected by this issue.

Hearing loss

Noise pollution is any unwanted or disturbing sound that affects the health and well-being of humans and other organisms. It is considered the second largest environmental cause of health problems, impacting the lives of millions of people.

The first signs of hearing damage from loud noises are tinnitus, a ringing or other sound in the ear that isn't from an external source, and difficulty understanding conversation in noisy situations. Children, with their developing auditory systems, are particularly vulnerable to the impacts of noise pollution, with over 1.1 billion young people worldwide at risk of hearing loss.

Continuous exposure to high-decibel environments can cause chronic hearing loss, as the damage to the hairs, membranes, and nerves of the inner ear is cumulative. Even moderate levels of noise can cause hearing damage if exposure is prolonged. Therefore, it is important to be aware of one's sound environment and take steps to protect one's hearing health, especially for those regularly exposed to loud noises.

Stress and high blood pressure

Noise pollution is a significant environmental problem that affects the health and well-being of millions of people worldwide. It is defined as any unwanted or disturbing sound that interferes with normal activities and diminishes one's quality of life. While noise-induced hearing loss (NIHL) is the most commonly discussed health effect, research has shown that exposure to constant or high levels of noise can lead to various adverse health impacts.

One of the significant ways that noise pollution affects human health is by causing stress and high blood pressure. Studies have found a strong link between exposure to transportation noise, such as road traffic and aircraft noise, and elevated blood pressure or hypertension. For example, a study found that a 5 dB increase in long-term exposure to aircraft noise was associated with an 8% increased risk of hypertension in men, and this estimate rose to 21% per 5 dB when participants who smoked or used snuff were excluded.

The mechanism by which noise causes stress and high blood pressure involves the activation of the body's stress response. Chronic exposure to unwanted or loud noise causes annoyance, which leads to increased levels of stress hormones such as cortisol and catecholamines. This chronic stress triggers various physiological changes in the body, including increased blood pressure, heart rate, and cardiac output, as well as changes in blood lipids and carbohydrates. These changes can ultimately manifest as cardiovascular diseases such as arterial hypertension, coronary artery disease, and stroke.

The impact of noise pollution on stress and high blood pressure is particularly concerning for children. Studies have found that noise pollution can affect a child's hearing at any stage of development and may lead to stress and other behavioural issues. Additionally, noise pollution can interfere with a child's ability to learn and may impact their behaviour, their ability to form relationships, and their confidence.

The problem of noise pollution is expected to persist or even worsen due to urban growth and increased mobility demand. Therefore, it is essential to implement noise mitigation measures to reduce the health risks associated with noise exposure. Combined strategies that address both noise and air pollution from traffic, including technological improvements, ambitious noise policies, better urban planning, and changes in people's behaviours, are necessary to effectively reduce noise levels and protect public health.

Cognitive impairment in children

Noise pollution is the spread of unwanted sounds into the environment. While noise is often overlooked as a health hazard, it is the second-largest environmental cause of health problems, according to some World Health Organization (WHO) findings. Unwanted sounds can have a range of effects on mental health. The brain is always monitoring sounds for signs of danger, even during sleep. As a result, frequent or loud noise can trigger anxiety or stress. Continued exposure to noise pollution can increase sensitivity to stress, making people feel irritable, on edge, frustrated, or angry.

Research also suggests that noise pollution may indirectly contribute to other health conditions. According to a 2018 review, there is evidence that short-term exposure to noise pollution can temporarily raise blood pressure and increase blood viscosity. There is also an association between long-term exposure to noise and higher rates of cardiovascular disease. The review authors suggest that this may occur due to the impact of noise pollution on stress hormone levels and the nervous system. Over time, this stress may contribute to the development of disease. Another 2018 study in Canada found that preeclampsia, a condition that causes high blood pressure during pregnancy, was more common among pregnant people exposed to higher levels of noise pollution.

Children are particularly vulnerable to the negative health effects of noise pollution. For children exposed to frequent or loud noise, it is important to monitor for signs of hearing loss. Regular checkups and hearing tests can help determine if there are any issues. Noise pollution can also affect a child's behavior, their ability to form relationships, and their confidence.

Environmental noise has been shown to contribute to cognitive impairment in children. A report from the European Environment Agency (EEA) estimates that 12,500 school children suffer from reading impairment due to aircraft noise. There is also moderate-quality evidence for an association between aircraft noise and reading and language in children. Meta-analyses suggest that reading ability is associated with noise exposure in children. For example, a meta-analysis found that reading comprehension scores in quiet classrooms were 0.80 points higher than children in noisier classrooms.

In addition to noise pollution, air pollution may also impair cognitive function in children and across the life course. Several studies have focused on the combined exposure to air and noise pollution, both of which are potentially detrimental to cognition in older adults. A study in Krakow, Poland, found that high prenatal exposure to air pollutants was associated with reduced nonverbal reasoning ability at 5 years of age, which corresponds to an average IQ decrease of 3.8 points. Another study on urban children found that nearly 40% of highly exposed children and young adults had frontal tau hyperphosphorylation with pre-tangle material, and 51% had amyloid-beta diffuse plaques. These effects were not seen in similar controls living in low-pollution areas.

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