Pollution's Impact: Our Body's Response And Resilience

Air pollution is a major health concern, with almost the entire global population (99%) breathing air that exceeds World Health Organization (WHO) guideline limits. It can affect everyone and has a wide range of negative impacts on the body, from respiratory issues to more severe problems like cancer and even premature death.

The main pathway of exposure to air pollution is through the respiratory tract, but some pollutants are small enough to enter the bloodstream via the lungs and circulate throughout the body. This can lead to systemic inflammation and damage to various organs, including the lungs, heart, and brain.

Both short-term and long-term exposure to air pollution can cause a variety of health issues, and certain populations are more vulnerable to its effects, including children, the elderly, and those with pre-existing health conditions.

With such pervasive impacts on human health, it is crucial to address and mitigate the sources of air pollution, which include vehicle exhaust, industrial emissions, and the burning of fossil fuels.

Respiratory issues: coughing, itchy eyes, and lung diseases

Coughing and Itchy Eyes

Air pollution can cause coughing and itchy eyes, with the eyes being one of the most important sensory organs affected by air pollution. The cornea is the most sensitive structure in the human body due to numerous innervations in the ocular surface, making it highly susceptible to environmental agents.

The eyes are protected by only a thin layer of precorneal tear film, which means human eyes are vulnerable to the adverse effects of air pollution. The adverse effects of air pollutants on the eyes include irritation and inflammation, with conjunctivitis being a frequent problem.

People who travel to highly polluted areas often suffer from extensive subclinical ocular surface changes. The mixture of air pollutants can lead to cytological changes and inflammation in the ocular surface, contributing to eye discomfort.

Lung Diseases

Air pollution can also cause serious lung diseases, including lung cancer, asthma, and chronic obstructive pulmonary disease (COPD). It can irritate the airways and increase lung symptoms, with some types of air pollutants reaching deep into the lungs and causing inflammation.

Particulate matter (PM), a mix of solid and liquid droplets, is one of the main pollutants affecting the lungs. Larger particles (PM10) arise from pollen, sea spray, and wind-blown dust, while finer particles (PM2.5) come from the combustion of fuels in power generation facilities, industries, or vehicles.

Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are also harmful. High levels of NO2 can irritate the airways, increasing the risk of asthma attacks and COPD flare-ups. SO2 can irritate the lining of the nose, throat, and lungs, causing coughing, tightness of the chest, and making it harder to breathe.

Long-term exposure to air pollution can lead to the development of lung conditions, including asthma and COPD. It can also increase the risk of lung infections like bronchitis and pneumonia, as well as playing a part in the development of lung cancer.

Children are more at risk than adults because their lungs are still developing, and they breathe faster, taking in more polluted air. Being exposed to pollution as a child increases the risk of developing asthma and COPD as an adult. Older people are also more at risk, especially if they have long-term lung conditions or heart disease.

Cardiovascular issues: heart disease, hypertension, and abnormal heartbeats

Air pollution has been linked to a wide range of cardiovascular issues, including heart disease, hypertension, and abnormal heartbeats.

Fine particulate matter (PM2.5) is a major contributor to these issues. These particles are small enough to penetrate the lung barrier and enter the bloodstream, affecting all major organs of the body. Research has shown that exposure to increased concentrations of PM2.5 over a few hours to weeks can trigger cardiovascular events, including heart attacks. Longer-term exposure can lead to an increased risk of cardiovascular mortality and decreased life expectancy.

Short-term exposure to air pollution can increase the risk of heart attack, stroke, arrhythmias, and heart failure in susceptible people, including the elderly or those with pre-existing medical conditions. The risk of death is greater from long-term exposure, as current science suggests that air pollution aids in the development and progression of atherosclerosis, or plaque buildup in the artery walls, which causes heart disease.

In addition to outdoor air pollution, indoor air pollution can also contribute to cardiovascular issues. Household air pollution, caused by the use of open fires or simple stoves for cooking fuelled by kerosene, biomass, coal, or other sources, can lead to exposure to dangerous levels of pollutants.

Overall, air pollution has been shown to have significant negative impacts on cardiovascular health, increasing the risk of heart disease, hypertension, and abnormal heartbeats.

Neurological issues: cognitive impairment, aggression, and anxiety

Air pollution has been linked to a range of neurological issues, including cognitive impairment, aggression, and anxiety. Here's a detailed look at how air pollution can affect these aspects of human health:

Cognitive Impairment

Air pollution has been found to have detrimental effects on cognitive function, including memory, attention, and overall intelligence. Studies have shown that exposure to air pollutants can lead to cognitive decline, with older adults being particularly vulnerable. Fine particulate matter, such as PM2.5, has been associated with an increased risk of dementia and Alzheimer's disease. Exposure to pollutants during pregnancy and early childhood can also impact brain development and cognitive abilities later in life.

Aggression

There is growing evidence that air pollution can contribute to aggressive behavior. Fine particulate matter, especially those emitted from vehicles, can enter the bloodstream and cause systemic inflammation, including in the brain. This inflammation can impair cognitive functioning, leading to more impulsive decision-making and aggressive behavior. Studies have found a positive correlation between exposure to fine particulate matter and violent crimes, with an increase in violent crimes across the United States associated with higher levels of PM2.5.

Anxiety

Recent studies have also linked air pollution to increased symptoms of anxiety. Exposure to particulate matter, especially PM2.5, has been associated with fearfulness, a desire for avoidance, and a tendency to worry. The mechanisms behind this link are still being explored, but it is believed that particulate matter may increase oxidative stress and inflammation, which are known to exacerbate anxiety.

Cancer: lung, bladder, and cardiovascular

Pollution has been linked to a variety of cancers and cardiovascular issues. Outdoor air pollution, in particular, has been connected to lung cancer, with some studies suggesting it may be responsible for roughly 1 in 10 cases of lung cancer in the UK.

Lung Cancer

Particle pollution in outdoor air, such as that from vehicle exhaust, coal-fired power plants, and other industrial sources, can cause lung cancer. Research has shown that smaller particles are more dangerous, as they get trapped deep in the lungs and can even enter the bloodstream, causing damage to our health.

In 2013, the World Health Organization (WHO) concluded that particulate matter causes lung cancer. This was supported by a study of over 400,000 people, which found higher rates of lung cancer in areas with high levels of PM2.5. The study also found that air pollution wakes up normally inactive cells in the lungs, encouraging them to grow and potentially form tumors.

Bladder Cancer

While smoking is the biggest risk factor for lung cancer, air pollution has also been linked to bladder cancer. A systematic review found positive associations between air pollution and bladder cancer mortality, although more studies are needed to confirm these findings.

Cardiovascular Issues

Air pollution has been closely associated with adverse cardiovascular effects, including an increased risk of heart disease, stroke, and altered blood pressure. Fine particulate matter (PM2.5) has been found to have a stronger correlation with adverse health effects than larger particles (PM10). Exposure to PM2.5 over a few hours to weeks can trigger cardiovascular disease-related heart attacks and death, while longer-term exposure can lead to increased risk of cardiovascular mortality and decreased life expectancy.

Studies have shown that air pollution is particularly harmful to vulnerable populations, including the elderly and those with pre-existing cardiovascular conditions. Additionally, air pollution has been linked to increased blood pressure, which is a risk factor for cardiovascular disease.

Pregnancy and foetal development: low birth weight and premature births

Air pollution can have a detrimental impact on foetal development, increasing the likelihood of low birth weight and premature births.

Low Birth Weight

Low birth weight is defined as a baby weighing less than five pounds and eight ounces. Exposure to air pollution during pregnancy is speculated to be a contributing factor to low birth weight. Research has indicated a correlation between higher levels of certain pollutants, such as nitrogen dioxide, and an increased risk of low birth weight.

A notable study in Beijing, a city known for its high levels of air pollution, examined the impact of reduced emissions and improved air quality during the 2008 Olympics. The study found that women who were in their eighth month of pregnancy during this period gave birth to babies with a slightly higher average weight compared to those born in the same months in previous years.

Additionally, a 2013 analysis of 14 population-level studies found a positive correlation between higher levels of certain pollutants and the risk of low birth weight.

Premature Births

Premature births, or births before 37 weeks of gestation, are also associated with exposure to air pollution. According to a study by The Stockholm Environment Institute, approximately three million babies are born prematurely each year due to air pollution. This accounts for 18% of all annual preterm births.

Furthermore, a 2019 study found that air pollution changes over time can influence the risk of preterm birth, with the highest risk occurring during a subsequent pregnancy.

Impact on Foetal Development

Air pollution can disrupt a baby's development, causing them to be born prematurely and with a low birth weight. Premature birth can lead to underdeveloped bodies and lungs, increasing the risk of death after birth.

Additionally, exposure to air pollution during pregnancy has been linked to an increased risk of asthma, wheezing, and reduced lung function in children.

Protecting Pregnant Women and Foetuses from Air Pollution

While it is challenging to avoid air pollution entirely, there are several measures that can be taken to reduce exposure:

• Monitoring air quality and staying indoors when pollution levels are high
• Avoiding contact with smokers and second-hand smoke
• Choosing routes with less traffic when walking
• Reducing intense outdoor exercise when pollution levels are high
• Using air purifiers and natural household cleaners
• Regularly checking for mould and installing carbon monoxide detectors

Frequently asked questions