Air Pollutants: Major Hazards To Human Health

Air pollution is a pressing global health issue, causing more than 6.5 million deaths annually. It is caused by a combination of human-made and natural sources, including vehicle emissions, fuel oils, natural gases, coal-fired power plants, chemical production, wildfires, and volcanic eruptions. Hazardous air pollutants, also known as air toxics, are released from industrial facilities and vehicles, causing serious health issues and environmental damage. These pollutants can be inhaled or ingested through contaminated water and food. The specific health risks associated with air pollution include respiratory issues, oxidative stress, inflammation, immunosuppression, mutagenicity, and various diseases. Fine particulate matter (PM 2.5), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), carbon monoxide, ground-level ozone, nitrogen dioxide, and sulfur dioxide are among the major air pollutants that pose significant threats to human health.

Fine particulate matter (PM2.5)

PM2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. It can decrease airway epithelial host defense functions, impair alveolar macrophage phagocytosis, and trigger the release of inflammatory cytokines, inflammasomes, adhesion molecules, and neutrophil chemotactic factors in the alveoli. It can also exacerbate inflammation in the lung by increasing Interleukin (IL)-5, IL-13, eotaxin, and monocyte chemotactic protein-3 (MCP-3). Each 10 μg/m3 increase in PM2.5 concentration with long-term exposure is associated with an ≥8% increased risk of lung cancer.

PM2.5 is associated with an increased risk of mortality. A study found that exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure. In the European Union, ambient air pollution primarily due to PM2.5 is responsible for 659,000 deaths per year, with 50-80% of these deaths due to cardiovascular events. A long-term study found that exposure to PM2.5 and NO2 increased the risks of colorectal and prostate cancers. Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

PM2.5 is also associated with respiratory diseases. It can induce oxidative stress-mediated pathways and pulmonary inflammation, stimulating the generation of mediators of pulmonary inflammation and promoting numerous illnesses. It contributes to and exacerbates bacterial lung infections and inflammatory lung conditions, and can induce asthma and COPD.

Ground-level ozone

Long-term exposure to ground-level ozone has been linked to aggravating asthma and potentially causing its development. Studies have shown that areas with elevated ozone concentrations have reported associations with deaths from respiratory causes. Additionally, ground-level ozone can lead to increased school absences, medication use, doctor visits, and hospital admissions, particularly for individuals with asthma and other lung diseases. The impact of ozone exposure can be influenced by various factors, including the ozone levels, breathing rate, and the amount of time spent outdoors.

To safeguard their health, individuals can take proactive steps on days with high levels of air pollutants, such as ground-level ozone. Staying indoors, limiting outdoor activities, and seeking information about air quality in their area can help reduce exposure to ground-level ozone. Additionally, advocating for the continued cleanup of air pollution and supporting policies that address this issue is crucial in mitigating the health risks associated with ground-level ozone exposure.

Carbon monoxide

Sources of carbon monoxide include vehicle emissions, fuel oils, and natural gas used for heating homes. Additionally, industrial processes, such as the combustion of gasoline, and power generation, particularly coal-fueled power plants, contribute significantly to carbon monoxide pollution.

When carbon monoxide is inhaled, it binds to hemoglobin in red blood cells, forming carboxyhemoglobin. This process interferes with the blood's ability to transport and release oxygen to the body's tissues and organs, resulting in oxygen deprivation. Prolonged exposure to carbon monoxide can lead to serious health issues, including brain damage and death.

The health effects of carbon monoxide poisoning can vary depending on the level and duration of exposure. Initial symptoms may include headaches, dizziness, confusion, nausea, and fatigue. As exposure continues or increases, more severe symptoms can develop, including loss of consciousness, cardiac problems, and respiratory failure. Certain individuals, such as those with cardiovascular or respiratory diseases, are particularly vulnerable to the harmful effects of carbon monoxide.

Reducing carbon monoxide emissions is crucial for safeguarding public health. Regulatory measures, such as the Clean Air Act, have been implemented to limit emissions from industrial sources. Additionally, public education about the risks of carbon monoxide and the importance of proper ventilation and the use of carbon monoxide detectors can help prevent accidental exposure in homes and workplaces.

Nitrogen oxides

Nitrogen dioxide (NO2) is one of the principal nitrogen oxides and is a significant contributor to air pollution. It is formed through the combustion of fuels and has a range of harmful health effects. Short-term exposure to elevated levels of NO2 can irritate the airways, aggravate respiratory diseases like asthma, and lead to coughing, wheezing, and difficulty breathing. Prolonged exposure to NO2 may also increase the risk of developing asthma and make individuals more susceptible to respiratory infections. Vulnerable subpopulations, including people with asthma, children, and the elderly, are at an even higher risk of experiencing adverse health impacts from nitrogen dioxide exposure.

Scientific studies have linked nitrogen oxides to a variety of health concerns. Research has found associations between exposure to nitrogen oxides and an increased risk of hemorrhagic stroke in post-menopausal women. Additionally, elevated levels of NO2, along with particulate matter and sulfur dioxide, have been strongly correlated with heart and lung harm, adverse pregnancy and birth outcomes, and an elevated risk of kidney and neurological damage, autoimmune disorders, and cancer. These pollutants contribute to particle pollution and the chemical reactions that form ozone, further exacerbating their impact on air quality and human health.

To protect themselves from the harmful effects of nitrogen oxides, individuals can take proactive measures such as advocating for the cleanup of air pollution and following air quality alerts. By staying informed about air quality levels and taking necessary precautions, individuals can minimize their exposure to harmful pollutants and reduce potential health risks associated with nitrogen oxides.

Sulphur oxides

Air pollution is a mix of hazardous substances from both human-made and natural sources. It poses a major threat to global health, with more than 6.5 million deaths each year globally attributed to it. Hazardous air pollutants are known to cause cancer and other serious health issues.

SO2 emissions can lead to high concentrations of SO2 in the air, which in turn leads to the formation of other sulphur oxides (SOx). SOx can react with other compounds in the atmosphere to form small particles, contributing to particulate matter (PM) pollution. These small particles can penetrate deeply into the lungs and, in sufficient quantities, can cause health problems.

At high concentrations, gaseous SOx can also harm trees and plants by damaging foliage and decreasing growth. SO2 and other sulphur oxides contribute to acid rain, which can harm sensitive ecosystems. Additionally, they can react with other atmospheric compounds to form fine particles that reduce visibility in certain parts of the world, creating a hazy atmosphere.

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. Individuals can take precautions on days with high levels of air pollutants and advocate for the continued cleanup of air pollution.

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