Air Pollutants: Harmful Impact On Human Health

Air pollution is a significant environmental health hazard that affects everyone, with nine out of ten people worldwide breathing polluted air. It is a mix of hazardous substances from both human-made and natural sources, including dust, fumes, gas, mist, odour, smoke or vapour. These pollutants can enter our bloodstream, causing or worsening many breathing and lung diseases, leading to hospitalizations, cancer, or even premature death. Both short-term and long-term exposure to air pollution can lead to a wide range of diseases, including stroke, chronic obstructive pulmonary disease, trachea, bronchus and lung cancers, aggravated asthma, lower respiratory infections, type 2 diabetes, obesity, systemic inflammation, Alzheimer's disease and dementia. Certain groups, such as older people, children, those with pre-existing health conditions, and low-income communities, are more vulnerable to the adverse health impacts of air pollution.

Air pollution increases the risk of respiratory infections, heart disease, stroke, and lung cancer

Air pollution is a major environmental health risk and a leading cause of premature death and disease. It can affect every organ in the body, exacerbating existing health conditions and increasing the risk of diseases later in life.

Fine particulate matter (PM2.5) is the air pollutant that causes the most significant health problems and premature mortality. These fine particles can penetrate homes and buildings, elevating indoor pollution concentrations. Short- and long-term exposure to PM2.5 can trigger cardiovascular events, including heart attacks, and increase the risk of cardiovascular mortality and decreased life expectancy. Research has shown that exposure to increased concentrations of PM2.5 over a few hours to weeks can lead to serious cardiovascular events, particularly in people with established heart disease. For example, people with chronic heart disease may experience symptoms such as coronary syndrome, arrhythmia, heart failure, stroke, and sudden cardiac death after exposure to fine particulate matter.

In addition to heart disease, air pollution is a leading cause of lung cancer. The International Agency for Research on Cancer has classified air pollution, particularly PM2.5, as carcinogenic to humans. The number of lung cancer deaths attributable to air pollution has increased by nearly 30% since 2007 as smoking rates have decreased and air pollution levels have risen.

Air pollution also increases the risk of respiratory infections. While high-income countries have experienced a decline in mortality rates, the incidence of strokes has increased significantly in low and middle-income countries (LMICs), where air pollution is projected to rise due to rapid industrialization. Evidence from epidemiological studies has demonstrated a strong association between air pollution and stroke, with the absolute risk at the population level comparable to "traditional" risk factors for cardiovascular disease.

Pollutants can enter the bloodstream and cause or worsen lung diseases, leading to hospitalisations and premature death

Air pollution is a major cause of disease and premature death. It is the single largest environmental health risk in Europe. Both short- and long-term exposure to air pollution can lead to a wide range of diseases, including lung cancer, stroke, chronic obstructive pulmonary disease, lower respiratory infections, and aggravated asthma.

Particulate matter, especially PM2.5, is a leading cause of cancer. These fine particles can reach the breathing sacs in your lungs, and ultrafine particles can cross into your bloodstream. They can also carry toxic chemicals linked to cancer. High levels of nitrogen dioxide, a brown toxic gas commonly found on busy roads and around industrial sites, can irritate the lining of your airways and make them more inflamed. This increases your risk of asthma attacks and COPD flare-ups.

When ozone levels are high, more people with lung conditions are admitted to hospital. Sulphur dioxide, produced by burning fuels like coal and oil, can cause coughing, tightness of the chest, and breathing difficulties. It can also cause smog. High levels of SO2 are associated with more hospital admissions for people with asthma.

Studies have shown a link between long-term exposure to air pollution and premature death. Short-term exposure may also be dangerous. When air pollution from fine particles or ozone increases, even intermittently, there is a substantial increase in deaths within a 2-day period. Older people, children, and those with pre-existing health conditions are more sensitive to the health impacts of air pollution.

Air pollution is linked to oxidative stress and inflammation in human cells, which may cause chronic diseases and cancer

Air pollution is a familiar environmental health hazard. It is a mix of hazardous substances from both human-made and natural sources. Almost 9 out of 10 people who live in urban areas are affected by air pollution. In 2021, the World Health Organization (WHO) published new air quality guidelines following a systematic review of the latest scientific evidence demonstrating how air pollution damages human health.

Air pollution is associated with oxidative stress and inflammation in human cells, which may cause chronic diseases and cancer. When pollutants come in contact with the lungs, they can initiate the synthesis of inflammatory mediators, macrophage activation, modulation of gene expression, and the activation of transcription factors, which are all related to the physiopathology of chronic respiratory diseases, including cancer. Oxidative stress can target biomolecules such as lipids, proteins, and even DNA/RNA, altering their structure and disrupting cellular functions. This can lead to systemic inflammation and carcinogenicity, impacting the lungs, heart, and brain, among other organs.

The International Agency for Research on Cancer of the WHO has classified air pollution as a human carcinogen, with particular reference to PM2.5. Studies have found that exposure to PM2.5 is associated with an increased risk of death. Additionally, maternal exposure to air pollution is associated with adverse birth outcomes, such as low birth weight, pre-term birth, and small for gestational age births.

Furthermore, air pollution is linked to an increased risk of specific diseases, including stroke, ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataract (household air pollution only). It is also associated with reduced lung function, asthma, and cardiac problems. Fine particulate matter can impair blood vessel function and speed up the calcification of arteries, increasing the risk of cardiovascular disease.

Pollutants can affect the foetus, causing low birth weight, pre-term birth, and small gestational age births

Air pollution is a significant environmental health risk, with the potential to affect every organ in the body and exacerbate existing health conditions. It is particularly harmful to vulnerable groups, including children, adolescents, older people, and those with pre-existing health issues.

Pregnant women and their foetuses are also highly susceptible to the adverse effects of air pollution due to the physiological changes that occur during pregnancy. Pollutants can impact the foetus, leading to potential complications such as low birth weight, pre-term birth, and small gestational age births.

Low birth weight is a recognised risk factor for a range of health issues, including developmental delays and increased mortality rates. Studies have found a direct correlation between exposure to particulate matter, particularly PM10, and low birth weight. Additionally, pollutants like sulfur dioxide (SO2) and nitrogen dioxide (NO2) have been linked to an increased risk of low birth weight during the third to fifth months of pregnancy.

Pre-term birth is also associated with air pollution exposure. Pollutants can induce pre-term labour, resulting in premature births. These babies are often very small, with underdeveloped bodies and lungs, which further increases the risk of health complications and death. The risk of pre-term birth is particularly high in subsequent pregnancies with exposure to pollutants.

Furthermore, air pollution has been linked to small gestational age (SGA) births. While fewer studies have addressed this relationship, exposure to particulate matter and pollutants during pregnancy is associated with an increased risk of SGA births. This suggests that air pollution may disrupt a baby's growth, causing them to be born unusually small.

Overall, the evidence indicates that air pollution can have significant adverse effects on foetal development, leading to potential complications during pregnancy and adverse health outcomes for the child. These findings highlight the importance of reducing air pollution levels and implementing preventive measures to protect the health of pregnant women and their foetuses.

Pollutants can also harm children before they are born, through their mothers' exposure

Air pollution is a familiar environmental health hazard, and it is the single largest environmental health risk in Europe. It is a mix of hazardous substances from both human-made and natural sources. It is present in the atmosphere in the form of dust, fumes, gas, mist, odour, smoke or vapour, in quantities and durations that can be harmful to human health.

The health impacts of air pollution are dependent on the types, sources, and concentrations of the pollutants in the air pollution mixture that an individual is exposed to. The main pathway of exposure from air pollution is through the respiratory tract. Breathing in these pollutants leads to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout our body, impacting the lungs, heart, and brain, among other organs, and ultimately leading to disease.

Furthermore, epidemiological and experimental evidence agree that gestational exposure to air pollution in urban settings increases the risks for low birth weight, preterm birth, congenital malformation, intrauterine growth restriction, and neonatal mortality. Exposures are also associated with increased risks for preeclampsia, hypertension, and gestational diabetes.

To protect themselves, pregnant women can take steps such as reading the Air Quality Index (AQI) and purchasing air purifiers for their homes.

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