Air Pollution: Can It Cause Allergies?

Air pollution is a global problem that affects our health. It is defined as the contamination of the air with harmful gases, chemicals, or small particles. These particles can be found in haze, smoke, soot, and airborne dust.

Air pollution can cause and worsen allergies and allergic diseases, including allergic rhinitis, asthma, and other respiratory diseases. Pollutants can also increase the allergenicity of certain pollens, facilitating their dispersion into smaller fractions.

People with lung diseases like asthma, people with heart disease, those who work or exercise outdoors, and individuals who are pregnant are among those at the highest risk from harmful effects of air pollution.

Air pollution can cause asthma and other lung diseases

Air pollution is the contamination of the air with harmful substances, such as gases, chemicals, or small particles. These small particles can be found in haze, smoke, soot, and airborne dust, and can lead to serious air quality problems.

Ozone, a common air pollutant, is helpful in the upper atmosphere but can cause problems when found in the air we breathe. It is associated with worsening respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD).

Nitrogen dioxide, which comes from burning fuels, can also cause someone to develop asthma and worsen lung disease.

Sulphur dioxide, which comes from burning fossil fuels, transportation, volcanoes, and industrial processes, can harm the lungs and lead to health problems.

Carbon monoxide, which forms from the incomplete combustion of fuels and wood, can be dangerous when it builds up inside buildings, homes, and cars.

Methane, another gas that is part of air pollution, is released from animal agriculture and melting permafrost. It can turn into ground-level ozone, which is harmful to human health.

The effects of air pollution on asthma and health include:

• Difficulty breathing deeply
• Worsened asthma symptoms
• Decreased lung growth in children
• Reduced lung function
• Needing more doses of asthma drugs
• Needing emergency treatment for asthma
• Heart and blood vessel diseases
• Adverse birth outcomes (such as preterm birth, low birth weight, stillbirth)

People with lung disease, heart disease, those who work or exercise outdoors, pregnant individuals, those who live near sources of pollution, people with lower incomes, and Black, Hispanic, and Native American/Indigenous communities are most at risk from harmful effects of air pollution.

Air pollution worsens asthma symptoms

Air pollution can worsen asthma symptoms and trigger asthma attacks. Pollutants in the air irritate the airways, causing them to swell and tighten, and leading to breathing problems.

Particulate matter, such as coarse particulate matter (PM10-2.5) from roadway particles like brake and tire wear, and mixtures of road dust and metals, can cause asthma in children and lead to hospitalisation. A study by Johns Hopkins University found that children exposed to outdoor coarse particulate matter were more likely to develop asthma and need emergency treatment.

Ground-level ozone, formed when chemicals from cars, power plants, and factories mix with sunlight, can also harm the lungs. Particle pollution, created when tiny bits of dust, dirt, smoke, soot, and other matter hang in the air, can cause breathing problems as the smaller the particles, the deeper they can get into the lungs.

Additionally, air pollution can make people more susceptible to upper respiratory infections, which can trigger asthma symptoms. Pollutants can also make the lungs more sensitive to allergens in the air.

Several studies have found a link between air pollution and asthma exacerbation. For example, a study of asthmatic children in Mexico City found that exposure to PM2.5, NO2, and O3 concentrations was associated with an increased incidence of exacerbated asthma. Another study of 60 adult volunteers with mild or moderate asthma found that walking for two hours in a heavily trafficked area with high levels of diesel led to significantly greater reductions in lung function than walking in a park with low levels of air pollution.

Overall, air pollution can worsen asthma symptoms, leading to breathing problems, increased hospitalisations, and a greater need for medication.

Air pollution can increase your risk of getting asthma

Yes, air pollution can increase your risk of getting asthma. Air pollution is the contamination of the air with harmful substances, such as gases, chemicals, or small particles. These pollutants can irritate the airways and make asthma worse. Small airborne particles, found in haze, smoke, soot, and airborne dust can lead to serious air quality problems.

Small airborne particles are called "particulate matter" or PM. The smallest particles (PM2.5) are the most dangerous. They can get deep into the lungs or even your blood.

People with asthma are at greater risk from breathing in small particles and irritating gases. They can irritate the airways and make asthma worse.

Ozone, a gas, is one of the most common air pollutants. It is helpful in the upper atmosphere but causes problems when it is found closer to the ground in the air we breathe. Ground-level ozone is part of "smog" or haze. It is most common in cities where there are more cars and use of fossil fuels. It is also more common in the summer when there is more sunlight, heat, and low winds. Ground-level ozone is created by chemical reactions between emissions of burning fuel emissions and volatile organic compounds (VOCs), heat, and sunlight. It is associated with worsening respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Ozone triggers asthma because it is very irritating to the lungs and airways.

Nitrogen dioxide (NO2) comes from burning fuels. It also forms from emissions from cars, trucks, other vehicles, and power plants. It is part of smog (haze). Breathing in NO2 can cause someone to develop asthma. It can worsen lung disease, especially asthma.

Sulfur dioxide (SO2) comes from burning fossil fuels, transportation, volcanoes, and industrial processes. It can be found in smog or haze. SO2 can harm plants (including trees). It can harm your lungs and lead to health problems.

Carbon monoxide (CO) forms from incomplete combustion of fuels and wood. It has no smell. It can be very dangerous when it builds up inside buildings, homes, and cars.

Methane (CH4) is another gas that is part of air pollution. It mostly comes from animal agriculture and in subarctic regions where it is released from melting permafrost. Fossil fuels (oil, gas, coal) and waste (food, landfills, wastewater) also add methane to the air. Methane is 30 times more potent at trapping heat than carbon dioxide (CO2) as a major greenhouse gas that is worsening the climate crisis. Methane can turn into ground-level ozone, which is harmful to human health.

Air pollution is linked to an increased prevalence of allergies

Air pollution is defined as the contamination of the air with gases, chemicals, or small particles that are harmful to human health or the environment. Sources of air pollution include gases such as ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and methane, as well as particulate matter like dust, pollen, and mold.

Air pollution has been linked to an increased prevalence of allergies and allergic diseases, including allergic rhinitis, allergic conjunctivitis, and asthma. Allergic respiratory diseases affect up to 40% of the global population and significantly impact individuals' quality of life.

Mechanisms and Risk Factors

The exact mechanisms behind the rapid increase in allergy prevalence remain uncertain, but air pollution is considered a causative factor. Air pollutants can directly or indirectly affect individuals and can also interact with aeroallergens, increasing their allergenicity. For example, air pollutants can disrupt pollen particles, leading to the release of paucimicronic particles that can more easily penetrate human airways.

Additionally, air pollution can alter the pulmonary development of children and adolescents and increase the risk of adverse birth outcomes, such as preterm birth and low birth weight. Exposure to air pollution during pregnancy has been associated with the development of asthma and allergic rhinitis in children.

Particulate Matter

Particulate matter, especially ultrafine particles, is a significant component of air pollution. These particles can easily enter the airways and even reach the alveoli, causing direct damage or triggering oxidative stress and activating various inflammatory pathways. Diesel exhaust particles, a major source of particulate matter in urban areas, have been found to stimulate human airway epithelial cells to produce cytokines relevant to airway inflammation, such as interleukin-8 and granulocyte-macrophage colony-stimulating factor.

Prevention and Management

To reduce exposure to air pollution, individuals can limit their time outdoors, especially during periods of high air pollution, and engage in indoor activities instead. Using air filters and air purifiers equipped with high-efficiency particulate air (HEPA) filters can also help improve indoor air quality and reduce exposure to allergens.

For individuals with allergies, allergen immunotherapy, or allergy shots, can be effective in improving and reducing symptoms over an extended period. Additionally, certain home remedies, such as using saline nasal sprays and essential oils, may help manage allergy symptoms.

Air pollution can cause early death

Air pollution can indeed cause early death. In the United States, it is estimated that outdoor air pollution is responsible for 5-10% of the total annual premature mortality. A study of 22 million adults aged 65 and older found that when air pollution from either fine particles or ozone increased intermittently, there was a substantial increase in deaths within a 2-day period. Each incremental increase of 10 micrograms of fine particles per cubic meter or 10 parts per billion of ozone was associated with a rise in deaths. The risk of death associated with air pollution was highest for those over 85 years old, females, non-white people, or economically disadvantaged people.

In the United Kingdom, emissions from cars, trucks, planes, and power plants cause 13,000 premature deaths each year. Among the various sources of emissions in the country, car and truck exhaust was the single greatest contributor, affecting some 3,300 people per year. This is higher than the number of people who died in road accidents in 2005. Emissions from shipping and aviation were the second greatest contributor, causing 1,800 early deaths annually, followed by power plant emissions, which cause an estimated 1,700 premature deaths each year.

In addition to the direct effects of air pollution on human health, it can also have indirect effects by increasing exposure to allergens. For example, pollen in heavily polluted zones can express a larger amount of proteins that are allergenic. Diesel exhaust particles can disrupt pollen particles, leading to the release of paucimicronic particles and facilitating their penetration of the human airways. Climate change can also lead to variations in the pollination calendar, with plants advancing and prolonging their pollination period in response to higher temperatures and CO2 concentrations.

Overall, there is strong evidence that air pollution increases the risk of premature death, with certain subgroups of the population being particularly vulnerable.

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