How Pollution Triggers Allergies: A Complex Link Explained

The prevalence of allergic diseases has increased globally, particularly in industrialised societies. While the exact causes of this increase are uncertain, a variety of air pollutants have been identified as a possible factor. These include ozone, nitrogen dioxide and particulate matter, which is generated by automobile traffic and industry. Epidemiological and toxicological research has found a relationship between air pollution and the exacerbation of asthma and other allergic diseases, suggesting that pollutants play a crucial role in their development.

Asthma and air pollution

The global increase in the prevalence of allergic diseases is of great concern. Urban air pollution has been attracting attention as an important environmental and extrinsic etiologic agent. This includes gaseous materials such as ozone (O3) and nitrogen dioxide (NO2), as well as particulate matter (PM), which is generated by automobile traffic and industry.

Strong epidemiological evidence supports a relationship between air pollution and the exacerbation of asthma and other allergic diseases. Indeed, recent studies have suggested that pollutants play a crucial role in the development of asthma and other allergic disorders.

The incidence of allergic diseases in most industrialised countries has increased. Although the exact mechanisms behind this rapid increase in prevalence remain uncertain, a variety of air pollutants have been attracting attention as one causative factor. Epidemiological and toxicological research suggests a causative relationship between air pollution and the increased incidence of asthma, allergic rhinitis, and other allergic disorders.

Asthma is exacerbated by numerous causes including the common cold, excess allergen exposure, drugs, and changes in the weather. The usual conditions that result from airborne allergens are hay fever, asthma, and conjunctivitis.

Allergic rhinitis and air pollution

There is a global increase in the prevalence of allergic diseases, particularly in industrialized societies. The exact mechanisms behind this rapid increase remain uncertain, but a variety of air pollutants have been attracting attention as one causative factor.

Urban air pollution has been identified as an important environmental and extrinsic etiologic agent. This includes gaseous materials such as ozone (O3) and nitrogen dioxide (NO2), as well as particulate matter (PM), which is generated by automobile traffic and industry.

There is strong epidemiological evidence supporting a relationship between air pollution and the exacerbation of asthma and other allergic diseases. Recent studies have suggested that pollutants play a crucial role in the development of asthma and other allergic disorders, including allergic rhinitis.

Allergic rhinitis affects the quality of life of millions of people worldwide. Air pollution not only causes morbidity, but nearly 3 million people per year die from unhealthy indoor air exposure. There is a clear interaction between allergic rhinitis and air pollution. Mechanisms, particularly oxidative stress, potentially explain the interactions between air pollution and allergic rhinitis.

Among several typical ambient air pollutants, there are correlations of allergic rhinitis symptoms with PM2.5, PM10, CO, SO2 and NO2, whereas O3 showed no such correlation.

The hygiene hypothesis

The global prevalence of allergic diseases has increased dramatically in recent decades, particularly in industrialised societies. While the exact causes of this rapid increase remain uncertain, a variety of air pollutants have been identified as a potential factor. These include ozone, nitrogen dioxide, and particulate matter, which is generated by automobile traffic and industry. Strong epidemiological evidence supports a relationship between air pollution and the exacerbation of asthma and other allergic diseases.

The 'hygiene hypothesis' is one theory that has been put forward to explain the increase in allergic diseases. This hypothesis suggests that a lack of exposure to bacterial infections during early life results in a failure to develop Th1-dominant, adult-type immune responses. Instead, the immune system remains in a Th2-dominant, infantile state, which is more prone to developing allergic diseases.

While the hygiene hypothesis provides a potential explanation for the increase in allergic diseases, it is not without its limitations. For example, it does not fully explain why some individuals develop allergies while others do not, even when exposed to similar environmental conditions. Additionally, the hypothesis has been criticised for oversimplifying the complex interactions between the immune system and the environment.

Despite these limitations, the hygiene hypothesis has important implications for understanding and managing allergic diseases. It suggests that early-life exposure to a diverse range of microorganisms may help to promote the development of a healthy immune system and reduce the risk of developing allergies. This has led to the development of potential interventions, such as probiotic supplements and exposure to farm animals, which may help to prevent or treat allergic diseases.

Particulate matter

PM is a mixture of solid particles and liquid droplets found in the air. Some are large or dark enough to be seen as soot or smoke. Others are so small that they can only be detected with an electron microscope. PM2.5 is considered fine particulate matter, while PM10 is coarse particulate matter. Ultrafine PM is also a concern.

PM can be made up of a number of components, including acids (such as nitrates and sulphates), organic chemicals, metals, and soil or dust particles. The particles are often a mix of solids and liquid droplets.

PM has been shown to cause allergic nasal and eye symptoms, worsening dyspnea caused by allergens, and multiple allergic symptoms.

The common cold and asthma

The global increase in the prevalence of allergic diseases is a cause for concern. Urban air pollution has been attracting attention as an important environmental and extrinsic etiologic agent. This includes gaseous materials such as ozone (O3) and nitrogen dioxide (NO2), as well as particulate matter (PM), which is generated by automobile traffic and industry.

There is strong epidemiological evidence supporting a relationship between air pollution and the exacerbation of asthma and other allergic diseases. Recent studies have suggested that pollutants play a crucial role in the development of asthma and other allergic disorders.

The incidence of allergic diseases in most industrialized countries has increased. Although the exact mechanisms behind this rapid increase in prevalence remain uncertain, a variety of air pollutants have been attracting attention as one causative factor. Epidemiological and toxicological research suggests a causative relationship between air pollution and the increased incidence of asthma, allergic rhinitis, and other allergic disorders.

Asthma is exacerbated by numerous causes including the common cold, excess allergen exposure, drugs, and changes in the weather. The usual conditions that result from airborne allergens are hay fever, asthma, and conjunctivitis.

Frequently asked questions