Air Pollution's Impact: Weakened Immunity And Health Risks

Air pollution has been linked to a wide range of health issues, including respiratory and lung diseases, neurological problems, cardiovascular issues, and various types of cancer. A growing body of research also suggests that air pollution can have a detrimental impact on the human immune system, our body's defence mechanism against diseases and infections. This is especially concerning as a weakened immune system can make individuals more susceptible to a range of illnesses.

The immune system is made up of different types of immune cells, each with specific functions. Air pollution has been found to disrupt the functioning of several key immune cells, including particle-clearing macrophages, inflammatory neutrophils, and dendritic cells.

Air pollution can cause respiratory infections and diseases, such as asthma and COPD

Air pollution can cause respiratory infections and diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Respiratory infections occur when pollutants weaken the body's immune system, making it less able to fight off infections.

Air pollution can directly and indirectly trigger asthma symptoms. Pollutants irritate the airways, causing them to swell and tighten, which leads to breathing problems. Pollutants can also increase the likelihood of upper respiratory infections, which can, in turn, trigger asthma symptoms. Furthermore, pollutants can make the lungs more sensitive to allergens, which are a common asthma trigger.

COPD is a progressive inflammatory lung disease characterised by a persistent obstruction of airflow from the lungs. Long-term exposure to air pollution can cause a decline in lung function and increase the risk of developing COPD. Studies have found positive associations between air pollution and COPD prevalence, incidence, and mortality. However, the evidence is not conclusive, and more research is needed to fully understand the complex relationship between air pollution and COPD.

To reduce the harmful effects of air pollution on respiratory health, it is important to be aware of air quality and take appropriate measures. This includes reducing time spent outdoors when air pollution levels are high, wearing masks, and improving indoor air quality by using air purifiers and clean fuels.

It can lead to the development of allergies

Air pollution can lead to the development of allergies in several ways. Firstly, it can cause an imbalance between antioxidant pathways and airway inflammation. This, in turn, can lead to conditions such as allergic rhinitis and asthma. Secondly, air pollution can affect the development of allergies by triggering inflammatory immune responses. Pollutants stimulate pro-inflammatory immune responses across multiple classes of immune cells, including particle-clearing macrophages, inflammatory neutrophils, and lymphocytes that enact those responses. This can result in the exacerbation of asthma and chronic obstructive pulmonary disease (COPD). Thirdly, air pollution can also affect gene expression and modify responses to pollution exposure. For example, gene polymorphisms involved in antioxidant pathways can alter how individuals respond to air pollution. Finally, air pollution can increase the allergenicity of certain pollens by dispersing pollen allergens into smaller fractions, which can affect both individuals with pollution allergies and those with pollen allergies.

It can cause irritation to the eyes, nose, mouth, throat and skin

Air pollution can have a range of adverse effects on the human body, including irritation to the eyes, nose, mouth, throat, and skin. These effects are caused by various pollutants in the air, such as dust particles, poisonous gases, and particulate matter.

Particulate matter, due to its small size, can be sucked deep into the airways and cause irritation to the eyes, nose, mouth, and throat. It can also trigger the release of white blood cells into the bloodstream, leading to inflammation. The presence of particulate matter can also cause an imbalance in the immune system by activating toll-like receptor 4 (TLR4), which identifies the specific characteristics of pathogens and activates the white blood cells.

Additionally, nitrogen dioxide, an air pollutant commonly found in traffic-related air pollution, can irritate the airways and decrease lung capacity. Ozone gas molecules can have similar effects, causing irritation to the eyes, nose, mouth, and throat.

The effects of air pollution on the immune system can vary depending on the type and amount of pollutant exposure, as well as individual factors such as age and pre-existing health conditions. For example, elderly individuals are more susceptible to the detrimental effects of air pollution due to age-related changes in their immune cells.

To protect against the harmful effects of air pollution, it is recommended to stay indoors when outdoor air pollution levels are high and ensure that indoor air quality is maintained.

Air pollution can cause neurological problems

The respiratory tract, from the nasal passages down to the airways and alveolar gas exchange units in the lungs, is the primary site of exposure to air pollution. Inhaled particulates and gases interact with epithelial cells lining the airways and professional immune cells within the airways. These cells can be stimulated by air pollution as the constituents of pollution trigger cellular signalling pathways.

A study by Columbia immunologists found that inhaled particles from environmental pollutants accumulate over decades inside immune cells in lymph nodes associated with the lung, eventually weakening the cells' ability to fight respiratory infections. The elderly are especially vulnerable to respiratory infections, as seen during the COVID pandemic. The death rate from COVID-19 is 80 times greater in people over 75 than in younger adults.

Additionally, air pollution has been linked to decreased function of the Forkhead box transcription factor (Foxp3) gene, which triggers Treg cell development. Treg cells are responsible for regulating the immune system and preventing it from reacting to non-pathogenic substances associated with allergy and asthma. When Treg function is low, inflammatory responses occur, leading to more severe asthma symptoms.

Air pollution also affects the wider immune system, including the neonate and gastrointestinal tract. It can cause irritation of the eyes, dry nose, mouth and throat allergies, skin itching, diminished energy levels, headaches, and dizziness.

To reduce the damage caused by air pollution, it is advisable to stay indoors when outdoor air pollution levels are high and ensure that indoor air quality is maintained.

It has been linked to an increased risk of certain cancers

Air pollution has been linked to an increased risk of certain cancers, including lung cancer, breast cancer, liver cancer, pancreatic cancer, and bladder cancer.

According to the World Health Organization (WHO), 99% of the world's population breathes unhealthy air, and air pollution is estimated to cause nearly seven million deaths per year. Low- and middle-income countries account for nearly 90% of premature deaths related to air pollution.

Fine particulate matter (PM2.5), a mix of solid particles and liquid droplets in the air, has been identified as a significant contributor to air pollution-related cancers. These particles can penetrate deep into the lungs and even enter the bloodstream. Sources of PM2.5 include coal- and natural gas-fired plants, cars, agriculture, wildfires, wood-burning stoves, unpaved roads, and construction sites.

Studies have shown that exposure to PM2.5 is associated with a higher risk of dying from any cancer. For every 10 micrograms per cubic meter (µg/m3) increase in PM2.5 exposure, the risk of dying from cancer rises by 22%. The risk of mortality from cancers of the upper digestive tract is 42% higher, while for cancers of the accessory digestive organs, including the liver, bile ducts, gallbladder, and pancreas, the risk increases by 35%. The risk of mortality from breast cancer is 80% higher, and for lung cancer, it is 36% higher.

The exact mechanisms by which air pollution increases the risk of cancer are still being investigated. However, it is believed that pollution may spark defects in DNA repair function, alterations in the body's immune response, or inflammation that triggers angiogenesis, the growth of new blood vessels that allow tumors to spread. In the case of digestive organ cancers, pollution could also affect gut microbiota and influence cancer development.

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