Particulate Air Pollution: Deadly Impact On Human Health

Particulate air pollution, also known as particle pollution or soot, is a mixture of tiny solid and liquid particles in the air we breathe. It is a growing threat to public health, with evidence suggesting that it is linked to a range of negative health effects, including respiratory and cardiovascular issues, and even premature death. The health impact of particulate air pollution depends on the types and concentrations of particles, as well as individual factors such as genetics, comorbidities, and sociodemographics. While everyone is at risk, certain subpopulations, including people of colour and those living near emission sources, are more vulnerable to the health impacts of this type of pollution.

Characteristics and effects of particulate air pollution

Increased risk of respiratory diseases

Exposure to particulate air pollution is a significant risk factor for respiratory diseases. The mixture of tiny solid and liquid particles in the air we breathe can have detrimental effects on respiratory health, especially for vulnerable populations.

Particulate air pollution has been linked to an increased risk of developing respiratory conditions and exacerbating existing ones. Studies have found associations between exposure to particulate matter and respiratory symptoms such as coughing, phlegm, wheezing, and irritation of the airways. In addition, particulate pollution can cause acute decrements in pulmonary function, inflammation of the airways and lungs, bronchial hyperreactivity, and acute phase reactions. These respiratory issues can lead to increased hospital admissions and emergency department visits, particularly for those with pre-existing respiratory conditions.

One of the most concerning aspects of particulate air pollution is its impact on vulnerable populations, including children, older adults, and individuals with pre-existing respiratory conditions. Children are particularly susceptible due to their developing immune and defence mechanisms, as well as their faster breathing rate, resulting in the inhalation of higher doses of pollutants. Older adults also face increased risks due to a higher prevalence of pre-existing respiratory and cardiovascular diseases, as well as the natural decline in physiological defences that occurs with age.

Additionally, individuals with asthma or chronic obstructive pulmonary disease (COPD) may experience worsened symptoms and increased severity of attacks due to particulate air pollution. This is because particulate pollution can trigger airway hyper-reactivity, bronchoconstriction, and inflammation, which are common mechanisms in asthma pathophysiology. Research has shown that improvements in air quality are associated with better lung function development in children, highlighting the importance of reducing particulate pollution.

The impact of particulate air pollution on respiratory health is a growing concern, and it is crucial to continue researching and implementing measures to reduce exposure and improve air quality, especially for vulnerable populations. By understanding the risks associated with particulate air pollution, individuals and communities can take steps to protect their respiratory health and well-being.

Cardiovascular issues

Particulate air pollution is a mixture of gaseous and particulate components, each of which has detrimental effects on the cardiovascular system. Fine particulate matter (particulate matter with diameters less than 2.5 µm or PM2.5) can increase the risk of cardiovascular events. Research by the US Environmental Protection Agency (EPA) and others has found that exposure to increased concentrations of PM2.5 over a few hours to weeks can trigger cardiovascular disease-related heart attacks and death. Longer-term exposure can lead to an increased risk of cardiovascular mortality and decreased life expectancy.

The EPA's research on particulate matter has provided critical science to develop and implement Clean Air Act regulations that protect the quality of the air we breathe. In 1997, the EPA promulgated a new standard for PM2.5, which was based largely on epidemiologic evidence. This decision was informed by a panel convened by the National Research Council, which evaluated the research needs in fields such as toxicology to better understand particulate air pollution exposures and health effects. As a result, approximately $450 million has been devoted to particulate air pollution research over the last decade, leading to major advances in understanding the mechanisms of particle effects and the determinants of PM2.5 exposures in the general population.

The American Heart Association (AHA) has also published scientific statements regarding air pollution and cardiovascular disease (CVD). The AHA concluded that short-term exposure to particulate matter air pollution contributes to acute cardiovascular morbidity and mortality, and that long-term exposure to elevated PM levels can reduce life expectancy by a few years. Several new studies have also demonstrated that residing in locations with higher long-term average PM levels elevates the risk for cardiovascular morbidity and mortality.

Air pollution is a growing public health problem and mortality due to this issue is expected to double by 2050. It is the largest environmental health risk and ranks ninth among modifiable disease risk factors, above other common factors such as low physical activity, high cholesterol, and drug use. Most of the excess deaths attributable to air pollution exposure are due to acute ischemic/thrombotic cardiovascular events. In addition to excess mortality, air pollution is associated with significant reductions in healthy life years and worker productivity.

Lung damage

Air pollution is a mixture of contaminants from various sources, and it can affect all parts of the body, including the lungs, heart, and brain. Particle pollution, or particulate matter (PM), is a mixture of tiny solid and liquid particles in the air we breathe. These particles are categorised as coarse, fine (PM2.5), and ultrafine (PM10). The smaller the particle, the more harmful it is to our health.

Long-term exposure to particulate matter in the air has been linked to lung damage and an increased risk of mortality. The deposition of these particles in the lungs can lead to inflammation and irritation of the airways, causing respiratory symptoms such as coughing or difficulty breathing. People with pre-existing lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD), are more susceptible to the harmful effects of particle pollution, which can aggravate their symptoms and increase the risk of hospitalisation.

Children are particularly vulnerable to the lung-damaging effects of particulate air pollution. This is because their lungs are still developing, and they breathe faster, taking in more polluted air. Exposure to air pollution during childhood increases the risk of developing asthma and COPD in adulthood. Poor indoor air quality, proximity to high-density traffic or industrial pollution sources, and limited access to medical services can further exacerbate the health risks for children.

In addition to respiratory symptoms, particulate air pollution has been linked to more severe lung conditions. Studies have found a positive association between fine particle exposure and lung cancer mortality. While the exact incidence rate of lung cancer due to fine particles is still being studied, there is evidence that particulate matter plays a role in the development of lung cancer. Furthermore, air pollution increases the risk of lung infections such as bronchitis and pneumonia.

The effects of particulate air pollution on lung health are a significant concern, especially in urban areas where almost nine out of ten individuals are affected. Reducing PM2.5 concentrations has been associated with reduced mortality risk, emphasising the importance of implementing measures to improve air quality and protect public health.

Cancer

Air pollution is a mixture of contaminants from a range of sources. These contaminants are characterised by their aerodynamic properties and are measured by their aerodynamic diameter in micrometres (μm). Particulate matter with an aerodynamic diameter of less than 2.5 micrometres is known as PM2.5.

PM2.5 is a major cause of concern when it comes to air pollution and its link to cancer. In 2013, the World Health Organization's (WHO) International Agency for Research on Cancer (IARC) reviewed all the available science and concluded that particulate matter causes lung cancer. The IARC classified PM2.5 in outdoor air pollution as carcinogenic to humans (IARC Group 1). The Global Burden of Disease 2019 study estimated that 15% of global lung cancer deaths are attributable to PM2.5 in outdoor air.

Further studies have also found a link between air pollution and an increased risk of several other types of cancer, including breast, liver, and pancreatic cancer. A study conducted in Hong Kong and Birmingham, United Kingdom, found that long-term exposure to ambient fine particulate matter was associated with an increased risk of mortality for these cancer types.

It is important to note that while air pollution is a risk factor for cancer, other factors such as diet and exercise may also play a significant role. Additionally, the effects of air pollution on cancer development can vary depending on geographical location and individual factors such as tobacco smoking.

While air pollution levels in the United States are well below those of China, even lower levels of particle pollution have been linked to lung cancer. This highlights the need to continue addressing and reducing unhealthy levels of harmful particle pollution globally.

Adverse birth outcomes

Air pollution has been linked to a range of adverse health effects, including cardiorespiratory diseases and cancer. In recent years, there has been a growing focus on the impact of air pollution on adverse birth outcomes.

Several studies have investigated the effects of particulate air pollution on adverse birth outcomes, with a specific focus on particulate matter with an aerodynamic diameter of less than 2.5 micrometers (PM2.5). Research has suggested that exposure to PM2.5 during pregnancy may increase the risk of adverse birth outcomes such as low birth weight (LBW), preterm delivery (PTD), and very preterm delivery (VPTD).

For example, a retrospective cohort study in Florida from 2004-2005 found that exposure to PM2.5 during all trimesters was associated with an increased risk of term LBW, PTD, and VPTD among singleton births. Similarly, a study in Kansas from 2000-2015 found that higher exposure to PM2.5 during the second and third trimesters was linked to an increased risk of preterm birth.

However, it is important to note that the results of these studies have been inconsistent. While some studies have found a positive association between PM2.5 exposure and adverse birth outcomes, others have found no significant difference. For instance, a study in Florida by Fleischer et al. in 2014 found no difference in birth outcomes between women exposed to higher levels of PM2.5 and those exposed to lower levels.

The inconsistent findings highlight the need for further research to fully understand the relationship between particulate air pollution and adverse birth outcomes. It is crucial to continue investigating the effects of different types of particulate matter, exposure levels, and timing of exposure during pregnancy on birth outcomes.

Overall, the current evidence suggests that minimizing population exposure to particulate air pollution is essential to reduce the risk of adverse birth outcomes. By understanding the specific effects of particulate pollution on pregnancy and birth outcomes, public health interventions can be designed to protect maternal and infant health.

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