Air Pollution: A Trigger For Allergies?

Air pollution is a major environmental risk to human health, and it has been on an exponential rise, giving rise to several diseases. The air we breathe contains a wide variety of particles, including allergens. The usual conditions that result from airborne allergens are hay fever, asthma, and conjunctivitis.

An allergy is an exaggerated reaction by the immune system in response to exposure to certain foreign substances. These foreign substances are normally seen as harmless by the immune system in non-allergic individuals, but in allergic individuals, part of the immune system generates a response.

Allergens may be inhaled, ingested, applied to the skin, or injected into the body. The symptoms depend on the route of entry and the type of allergen. For example, allergens in foods may prompt the release of mediators in the skin and cause hives.

The most common airborne allergens include pollen, pet dander, dust mites, and mold spores. Exposure to these allergens can cause symptoms such as sneezing, coughing, fatigue, and watery eyes.

Air pollution can worsen the effects of allergens. A recent WHO study found that 9 out of 10 people on Earth breathe highly polluted air. The robust industrial development and the increasing number of vehicles on the road have made it challenging to escape air pollution.

High concentrations of chemicals such as nitrogen dioxide, sulfur dioxide, and diesel exhaust particles from motor vehicles and factories pollute the air we breathe every day. These air pollutants can aggravate the allergenicity of certain pollens, making it difficult for people with pollen allergies to manage their symptoms.

Therefore, it is essential to understand the link between air pollution and allergies to develop effective strategies for prevention and management.

Pollution and allergic rhinitis

Allergic rhinitis (AR) is a non-communicable, IgE-mediated inflammatory disease caused by type 1 hypersensitivity reactions induced by allergen exposure. AR symptoms include rhinorrhea, itching, sneezing, bronchial hyperresponsiveness, or airflow obstruction. Due to the nature of AR symptoms, the condition is often ignored, misdiagnosed, and thought not to be overly detrimental. However, AR has a substantial socioeconomic burden, affecting sleep length and quality, productivity, and quality of life.

Prevalence

AR prevalence has been estimated at 10-30% of adults in the United States and Europe, with up to 40% incidence in children. However, the true incidence might be indeterminable as data collection relies on physician diagnosis and may not account for undiagnosed or self-medicating individuals. AR is estimated to generate $2-5 billion annually in direct health-related costs in the United States alone.

Air Pollution and AR

There is a well-established association between air pollution and the rising prevalence of allergic diseases, including AR. Air pollution refers to substances emitted by fuel combustion, power generators, industrial facilities, or agricultural waste sites in the ambient air and can take the form of solid particulate matter (PM), liquid, or gaseous emissions.

Diesel exhaust particles (DEP) from motor vehicle emissions have been implicated in the rising prevalence of allergic disease and allergic sensitization. DEP acts as an adjuvant, enhancing the immune response to aeroallergens associated with AR through various mechanisms, including the upregulation of inflammatory signalling pathways.

Management and Treatment

The first-line treatment for AR includes oral or nasal corticosteroids and allergen avoidance. Allergen immunotherapy, such as allergy shots, can also help reduce the immune system's response. Fexofenadine hydrochloride (Allegra®) is an oral antihistamine that has been shown to alleviate AR symptoms aggravated by diesel exhaust particulates.

In conclusion, air pollution, particularly diesel exhaust particles, has been positively associated with the prevalence of allergic rhinitis. Children and adolescents are more sensitive to air pollution than adults, and the effects of air pollutants are generally more significant in developing countries. Management of AR exacerbated by air pollution includes allergen avoidance, corticosteroids, and targeted medications like antihistamines.

Pollution and asthma

Air pollution can cause asthma and other lung diseases. It can also worsen the symptoms of asthma, leading to more hospital visits and, in some cases, early death.

Air pollution is the contamination of the air with harmful substances, including gases, chemicals, and small particles. These particles can be found in haze, smoke, soot, and airborne dust. Small airborne particles are called "particulate matter" or PM. The smallest particles (PM2.5) are the most dangerous as they can get deep into the lungs or even the bloodstream.

Both long-term and short-term exposure to air pollution can cause serious health problems, especially for people with asthma. Breathing in air pollution can cause difficulty breathing, decreased lung growth in children, reduced lung function, and can lead to heart and blood vessel diseases.

Who is Most at Risk from Air Pollution?

While high levels of air pollution can be harmful to everyone, even lower levels can be detrimental to certain groups. These include people with lung disease, heart disease, those who work outside, those who are pregnant, and people who live near sources of pollution such as busy roadways and industrial facilities.

The Environmental Protection Agency (EPA) reports air pollution levels using the Air Quality Index (AQI). When the AQI is 101 or higher, it is considered unhealthy for people with asthma, and they may need to adjust their activities and medications. Many local weather forecasts will also warn the public about high air pollution days.

If you live in an area with poor air quality, pay attention to pollution levels and plan indoor activities for your child when the air quality is poor. Run the air conditioning and limit your child's outdoor activities. Make sure your child always has their quick-relief asthma medication on hand.

Pollution and eczema

Atopic dermatitis (AD), commonly referred to as eczema, is an inflammatory skin disease characterised by a weakened skin barrier and a heightened immune response to irritants and allergens. While the underlying mechanisms in the pathogenesis of AD are not fully understood, it is generally accepted that the interplay of individual genetic predisposition and environmental factors contribute to the development of AD.

Air Pollutants

Air pollution has been regarded as an important extrinsic, environmental, degrading etiologic agent. The severity of air pollution, particularly by combustion of engines, industrial factories, and heating systems in buildings, has been associated with the greater prevalence of allergic diseases in industrialised countries.

Air pollutants consist of a number of substances in the air that can have hazardous effects on human health. They exist in either particulate or gaseous form and are classified as primary or secondary pollutants depending on their sources of occurrence. Major primary pollutants include sulfur oxide compounds, nitrogen oxide compounds, carbon monoxide, volatile organic compounds, particulate matter (PM), toxic metals, and radioactive pollutants. Secondary pollutants are formed from primary pollutants in the atmosphere through chemical and photochemical reactions. Secondary pollutants include ground-level ozone, nitrogen dioxide, sulfuric acid, and smog.

Air Pollutants and Eczema

A number of cross-sectional studies have revealed an association between exposure to air pollutants and eczema symptoms. In a study, eczema symptoms were significantly associated with benzene, PM10, nitrogen oxide compounds, and CO exposure in 9- to 11-year-old children. In Taiwan, a nation-wide survey involving over 30,000 children demonstrated that flexural eczema was positively associated with exposure to traffic-related air pollutants. A birth cohort study in an urban area showed strong positive relationships between the distance to the nearest main road and eczema, while NO2 exposure was positively associated with eczema.

Several studies have shown that outdoor air pollution influences the prevalence of AD. In a study involving 4907 French children, the lifetime prevalence of AD eczema was significantly associated with 3-year averaged concentrations of PM10, nitrogen oxide compounds, and CO. In the urban US birth cohort study, exposure to butyl benzyl phthalate during pregnancy was associated with eczema development at 2 years of age. These studies suggest that outdoor air pollution is one of the potent risk factors for the development of AD.

As well as the effects on the prevalence of AD, outdoor air pollution influences the skin symptoms in AD patients. In a prospective study, the concentrations of outdoor PM10, PM2.5, toluene, and total volatile organic compounds were higher on days when the patients had symptoms of AD than on days when they reported no symptoms. It was found that an increased concentration of outdoor PM10 by 1 μg/m3 was significantly associated with a 0.44% increase in AD symptoms on the following day. The effect of PM on AD was also investigated in a study of 41 school children aged between 8 to 12 years. In this study, the pruritus score was significantly associated with the concentrations of PM with a diameter less than 0.1µm but not for larger particles.

In summary, air pollution is a complex mixture that includes certain solid particles, liquid droplets, and gaseous molecules. The US Environmental Protection Agency has identified criteria air pollutants that are common in the US and have well-known adverse human health effects, including ozone, PM, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Solid particles, often including ultra-fine particles smaller than 0.1 microns, are found in dust, smoke, and soot.

While the comprehensive effects of environmental chemicals as triggers of AD are still a subject of debate, eliminations of those with known correlation with AD might improve AD symptoms. Future studies should further investigate the specific mechanisms that contribute to these relationships for better management of AD in our daily life.

Pollution and anaphylaxis

Air pollution is a major environmental risk to human health, causing a range of respiratory problems, including allergic diseases. Anaphylaxis is a severe and potentially life-threatening allergic reaction that can be triggered by various factors, including air pollution. In this article, we will explore the link between pollution and anaphylaxis, discussing the mechanisms by which pollution can induce or exacerbate allergic responses and the potential health implications.

Air Pollution and Allergic Diseases

Air pollution refers to the presence of man-made or synthetic particulate matter (PM) in the atmosphere, which can include gases such as sulfur dioxide, ozone, nitrogen species, carbon monoxide, and PM such as diesel exhaust particles. The increase in industrialization, urbanization, and motor vehicle use has led to a rise in air pollution levels globally. According to the World Health Organization (WHO), 9 out of 10 people worldwide breathe polluted air.

Numerous studies have established a link between air pollution and the development or exacerbation of allergic diseases, including allergic rhinitis, asthma, and eczema. Air pollution can act as an adjuvant, enhancing immune responses to allergens and increasing the production of immunoglobulin E (IgE) antibodies, which are associated with allergic reactions.

Impact of Air Pollution on Anaphylaxis

While the direct link between air pollution and anaphylaxis requires further investigation, there is evidence to suggest that pollution can contribute to the development or triggering of anaphylactic reactions. Here are some potential mechanisms:

• IgE-Mediated Responses: Air pollution, particularly diesel exhaust particles (DEPs), can act as adjuvants, enhancing IgE-mediated immune responses. This means that exposure to air pollutants may increase the sensitivity of individuals with allergies, making them more susceptible to anaphylaxis triggers.
• Oxidative Stress: DEPs and other air pollutants can induce oxidative stress in the body, leading to the overproduction of reactive oxygen species. This can result in cellular damage and disrupt the body's antioxidant defense mechanisms, potentially triggering anaphylactic reactions in susceptible individuals.
• Inflammatory Responses: Air pollution, especially DEPs, can induce pro-inflammatory responses in the respiratory tract. This includes the release of cytokines, chemokines, and adhesion molecules, which contribute to airway inflammation and hyperresponsiveness. Such responses may increase the likelihood of anaphylaxis in individuals with respiratory allergies.
• Allergen Dispersion: Air pollutants can disperse pollen allergens into smaller fractions, increasing their aerosolization and the potential for inhalation. For individuals with pollen allergies, this increased exposure may trigger anaphylactic reactions.
• Prenatal and Early-Life Exposure: Exposure to air pollution during prenatal and early life stages can alter immune development and increase the risk of allergic diseases later in life. This includes an increased susceptibility to anaphylaxis triggers.

Health Implications

The health implications of the link between pollution and anaphylaxis are significant. Anaphylaxis is a medical emergency that requires immediate treatment with epinephrine (adrenaline). Delays in treatment can be life-threatening. Therefore, understanding the role of pollution in triggering anaphylaxis is crucial for public health interventions and individual risk management.

Air pollution has been linked to the development and exacerbation of allergic diseases, including respiratory allergies. While the direct link between pollution and anaphylaxis requires further research, there is evidence to suggest that pollution can contribute to the triggering of anaphylactic reactions through various mechanisms. These include IgE-mediated responses, oxidative stress, inflammatory responses, allergen dispersion, and prenatal/early-life exposure. Understanding this link is essential for developing strategies to reduce the impact of pollution on allergic diseases and anaphylaxis, ultimately improving public health outcomes.

Pollution and respiratory problems

Air pollution is a major environmental concern, with a recent WHO study finding that 9 out of 10 people worldwide breathe highly polluted air. The effects of air pollution on human health are far-reaching, with 7 million premature deaths occurring annually due to air pollution.

Respiratory Problems Caused by Pollution

Air pollution can cause and exacerbate various respiratory problems, including:

• Allergic respiratory diseases, such as allergic rhinoconjunctivitis and asthma.
• Chronic inflammation of the airways.
• Respiratory infections.
• Lung cancer.
• Heart diseases.
• Strokes.

Impact of Air Pollution on Respiratory Health

Air pollution can have detrimental effects on respiratory health, especially in vulnerable populations such as children, older adults, and those with pre-existing respiratory disorders. Exposure to air pollution can induce inflammation, create oxidative stress, and impair lung function.

Fine particles from traffic-related and industrial activities, such as ozone, nitrogen dioxide, and particulate matter, have been linked to an increased incidence of asthma, allergic rhinitis, and other allergic disorders. Air pollution can also aggravate existing respiratory conditions, leading to more frequent emergency department visits and hospital admissions.

Measures to Reduce Adverse Effects of Air Pollution

To reduce the adverse effects of air pollution on respiratory health, individuals can:

• Regulate their daily activities based on air quality indices, reducing time spent outdoors when pollution levels are high.
• Wear personal protective equipment, such as N95 masks, to filter out particulate matter.
• Improve indoor air quality by using clean fuels, improving stoves, and utilizing air cleaners.
• Quit smoking, as smoking is both a source of indoor air pollution and a risk factor for respiratory diseases.
• Maintain a healthy diet rich in antioxidants, as nutrients can help defend against the detrimental effects of air pollution.

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