Respiratory Health: Pollutants And Their Effects

Air pollution is a global health threat, causing millions of human deaths annually. Sulphur dioxide is one of the pollutants that affect the respiratory tract in humans. Other pollutants include nitrogen oxides, ozone, carbon monoxide, and particulate matter, which can lead to respiratory symptoms and changes in lung function. The respiratory system is particularly sensitive to air pollutants due to its mucous membrane lining. These pollutants can cause a range of respiratory issues, from minor irritation to chronic respiratory diseases, lung cancer, and acute respiratory infections.

Nitrogen oxides

Nitrogen dioxide (NO2), a common nitrogen oxide, has been linked to a range of adverse respiratory effects, including inflammation of the airways, worsened cough and wheezing, reduced lung function, and an increased frequency of asthma attacks. Scientific evidence suggests that exposure to NO2 could cause asthma in children and increase respiratory symptoms in people with existing asthma. Additionally, NO2 exposure is associated with heart and lung harm, affected pregnancy and birth outcomes, and an increased risk of kidney and neurological harm, autoimmune disorders, and cancer.

NOx particles can get deep into the respiratory system and alter lung tissue, causing long-term health effects. Those most susceptible to the harmful effects of NOx include children, the elderly, pregnant individuals, and people with existing lung diseases like asthma, chronic obstructive pulmonary disease (COPD), and cardiovascular disease.

NOx emissions come primarily from trucks, buses, cars, diesel-powered equipment, industrial processes such as oil and gas production, industrial boilers, and coal-fired power plants. However, emissions of nitrogen oxides are decreasing due to cleanup efforts and more stringent air quality standards.

Sulphur dioxide

Long-term exposure to high levels of SO2 increases respiratory symptoms and reduces lung function. Short exposures to peak levels of SO2 in the air can also cause breathing difficulties for people with asthma when they are active outdoors. Sulphur dioxide is particularly dangerous for children, older adults, and those with pre-existing respiratory conditions.

To protect themselves from the harmful effects of SO2, individuals can stay indoors and reduce physical activity when pollution levels are high. People can also advocate for policies that require cleaner fuels and pollution controls on power plants to reduce emissions and improve air quality.

Ozone

Breathing in ground-level ozone can result in a number of adverse health effects, including:

• Induction of respiratory symptoms such as pain, burning, or discomfort in the chest when taking a deep breath, and chest tightness, wheezing, or shortness of breath.
• Decrement in lung function, including reductions in forced expiratory volume.
• Inflammation of airways.
• Increased susceptibility to respiratory infections.
• Aggravation of pre-existing lung diseases such as asthma, emphysema, and chronic bronchitis.
• Increased frequency of asthma attacks.

These effects can be more severe in people with pre-existing lung diseases such as asthma, and can lead to increased school absences, medication use, doctor visits, emergency room visits, and hospital admissions.

Long-term exposure to ozone is also associated with serious health risks, including:

• Increased respiratory illnesses.
• Metabolic disorders.
• Nervous system issues.
• Reproductive issues, including reduced fertility and poor birth outcomes.
• Cancer.
• Increased cardiovascular mortality.

Research has also shown that lower levels of ozone can cause harm. For example, a 2017 study found that older adults faced a higher risk of premature death even when ozone pollution levels remained well below the current national standard.

Carbon monoxide

CO is known to increase the concentration of carbon monoxide in exhaled air, particularly in patients with asthma, bronchiectasis, and upper respiratory tract viral infections. It is important to note that non-smokers and ex-smokers are also susceptible to the harmful effects of CO. Elevated levels of CO in exhaled air can indicate an inflammatory process within the airways caused by infection. This can be detected through simple CO measurements, and a subsequent decrease in exhaled CO levels after treatment can indicate a reduction in inflammation.

The respiratory system has defence mechanisms in place to protect against inhaled foreign particles, including the mucociliary clearance process. However, air pollutants like CO can damage the respiratory lining and impair this natural defence mechanism, leading to symptoms such as a productive cough and dyspnoea.

Additionally, CO has been linked to an increased risk of respiratory infections. Prolonged exposure to elevated levels of air pollutants, including CO, can contribute to reduced respiratory function even in healthy individuals. It is important to minimise exposure to air pollution and take preventive measures to protect respiratory health.

In summary, carbon monoxide is a significant respiratory tract pollutant that can be absorbed from the upper respiratory tract and affect respiratory health. It can cause inflammation, increase susceptibility to infections, and lead to various respiratory symptoms. Proactive steps to reduce exposure and mitigate health effects are crucial to protect respiratory function.

Particulate matter

PM poses a significant risk to human health, particularly to the respiratory system. It can be inhaled and deposited in the lungs, especially in the alveoli. The adverse effects of PM on respiratory health have been well documented. Increased exposure to high concentrations of PM is associated with the development of lung cancer and an increased mortality rate. Additionally, PM exacerbates respiratory symptoms in patients with chronic airway diseases, including chronic obstructive pulmonary disease (COPD) and bronchial asthma. Long-term exposure to PM has also been linked to a higher prevalence of COPD and lung cancer in adults, leading to a decline in pulmonary function.

The impact of PM on respiratory health varies with particle size. Coarse particulate matter, with a diameter between 10 μm and 2.5 μm, is referred to as PM10-2.5. Fine particulate matter, with a diameter of less than 2.5 μm, is known as PM2.5 and can penetrate deep into the lungs. Ultrafine particles, with a diameter of less than 0.1 μm, can even enter the bloodstream and travel to distal organs.

The deposition of PM in the respiratory tract is influenced by particle size, water solubility, and chemical reactivity. Coarse particles are typically deposited in the extrathoracic region, which includes the nasal, pharyngeal, and laryngeal passages. Fine and ultrafine particles can reach the alveolar region, where they are cleared by mucociliary clearance and phagocytosis by macrophages. However, prolonged exposure to high concentrations of PM can overwhelm these defence mechanisms, leading to respiratory issues.

To protect individuals from the harmful effects of PM, it is recommended to wear face masks that filter out PM, especially in areas with high PM concentrations. Additionally, reducing the total amount of PM through national policies and early management of exacerbated patients are crucial factors in mitigating the health risks associated with PM exposure.

Frequently asked questions