Did you know? These are the most common culprits for seasonal allergies

Allergies are the sixth leading cause of chronic disease. Every year, some people are affected by common seasonal allergies. About 8% of the population suffers from allergic rhinitis, a condition known as hay fever, which tends to strike in spring, summer and early fall. Seasonal allergies occur when the immune system perceives harmless environmental substances as dangerous pathogens. In response, the body releases compounds such as histamine, leukotrienes and prostaglandins, which cause common hay fever symptoms such as sneezing, coughing, runny nose, watery eyes, congestion and fatigue.

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But what substances are most likely to cause hay fever? Here, we discuss the most common causes of seasonal allergies.

Weed pollen

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Pollen is the male reproductive cell of various plants. The proteins, oils and polysaccharides contained in pollen can all become allergens.

Pollen allergy is a series of clinical symptoms such as allergic rhinitis, conjunctivitis, asthma, dermatitis, etc. caused by immune response of allergic people after contact with allergenic pollen. The symptoms of pollen allergy patients are obviously seasonal and regional, and are easily affected by the weather. Wind speed of 2-3 meters/second can directly cause pollen allergy.

The peak season for pollen allergies and the severity of symptoms mainly depend on the transmission route of the allergenic pollen and the characteristics of the flowering period. Therefore, not only spring, but also summer and autumn are the peak seasons for pollen allergies.

Pollen in nature is mainly divided into wind-pollinated pollen and insect-pollinated pollen.

Flowers that rely on bees, butterflies and other insects for pollination are called "insect-pollinated flowers". Flowers that are highly ornamental are generally "insect-pollinated flowers", such as cherry blossoms, azaleas, peonies, tulips, etc. The pollen particles of these flowers are large and sticky, and cannot float in the air. Only a very small number of people are allergic to them.

Flowers that use wind as a medium for pollination are called "wind-pollinated flowers", which mainly come from trees (in spring) or weeds (in autumn). These flowers are very small, not very ornamental, not bright, and not fragrant, but the amount of pollen is very large and the particles are small. They are mainly spread by wind and can be blown far away by the wind. The diameter of pollen is generally 30-50 microns. When they float in the air, they can be easily inhaled into the respiratory tract. People with a history of pollen allergies will have allergic reactions after inhaling these pollens. Wind-pollinated pollen is the main source of allergies.

In spring, wind-pollinated pollen is mainly tree pollen, and common plants include elm, poplar, willow, cypress, etc. In summer, wind-pollinated pollen is mainly grain plant pollen, and common plants include corn, sorghum, wheat, etc. In autumn, wind-pollinated pollen is mainly weed pollen, and common plants include Artemisia, ragweed, Kochia, castor, etc.

Mold

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Mold is a type of fungus that produces spores that float in the air. It can grow on almost anything when there is a damp or humid environment. It can be found both indoors and outdoors. Mold is also a common cause of allergy and asthma symptoms.

Not all molds cause allergy symptoms. Some of the most common molds that cause allergy symptoms are:

Alternaria alternaria

Aspergillus

Cladosporium

Penicillium

Mildew is also a common type of mold.

Molds reproduce and grow differently than plants or animals. "Seeds" called spores travel through the air. Disturbing the source of mold can send spores into the air. Some spores travel in dry, windy weather. When humidity is high, they travel in fog or dew. This makes it easier for you to breathe spores into your lungs.

Inhaling the spores can cause allergic reactions in some people. Allergic symptoms from fungal spores are most common from July to early fall. Fungi grow in many places. They can grow both indoors and outdoors, so allergic reactions can occur year-round.

Many molds grow on rotting logs and fallen leaves, in compost piles, and on grass and grain. Unlike pollen, molds do not die with the first killing frost. Most outdoor molds become inactive over the winter. In the spring, they grow on plants that have been killed by the cold. Indoors, fungi grow in damp areas such as bathrooms, kitchens, or basements.

Fungal spores

It is well known that fungi can pose a serious health threat, but the focus is often on infections caused by fungi, while the relationship between fungi and allergies has been largely overlooked.1-3 In fact, the incidence of fungal sensitization is high, and allergic diseases caused by fungi are more severe than those caused by other inhaled allergens.

Fungi are a large class of eukaryotic microorganisms widely distributed in nature. Their basic structure includes spores and/or hyphae. After fungal spores and/or hyphae enter the human body through various pathways, they may cause allergic reactions.

Most fungi are not heat-resistant, and their optimum growth temperature is usually 18℃-22℃. They rarely cause infection, but may act as allergens and cause allergic reactions. Heat-resistant fungi such as Aspergillus and Penicillium can grow at body temperature and may act as allergens to cause allergic diseases, or as conditional pathogens to cause infection10.

To date, more than 80 genera of fungi have been shown to induce type I allergic reactions, and the most common fungal allergens include Alternaria, Cladosporium, Aspergillus, and Penicillium.

Fungal spores are always present in the air, with the highest concentrations in summer and autumn, usually 100-1000 times the concentration of pollen grains. Large fungal spores (>10µm) usually settle in the nasopharynx, causing symptoms of pollinosis; most fungal spores are smaller, between 2μm-10μm, and small fungal spores and fragments of large fungal spores can reach the lower airways, causing symptoms such as asthma.

Dust mites

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Dust mites are tiny organisms that are invisible to the naked eye and feed on animal dander. They are a strong allergen that can cause a variety of allergic diseases and threaten human life and health.

There are about 10 types of dust mites associated with allergic diseases, the most important of which are house dust mites and dust mites. The main conditions that affect the survival of dust mites are temperature and humidity. Dust mites grow best in an environment with a temperature of 22 to 26 degrees Celsius and a humidity of more than 50%.

Dust mites and their excrement can cause the following symptoms: sneezing, runny nose, stuffy nose, itchy nose, coughing, wheezing...

When dust mite allergy triggers asthma, you may experience: difficulty breathing, chest tightness, chest tightness or chest pain, a hissing sound when breathing out, and sleep disorders due to shortness of breath, coughing or gasping.

Dust mite control is part of the overall treatment of allergic diseases. Patients with perennial allergic rhinitis, asthma or atopic dermatitis who are allergic to dust mites should develop appropriate dust mite control measures based on the severity of the disease, the climate conditions of the place where they live, and their personal living environment.

Healthy adults who have never been allergic to dust mites do not need to remove dust mites specifically. Daily cleaning and regular drying of bedding are enough. If you are allergic to dust mites, you must take strong measures to remove dust mites in order to avoid allergic reactions.

The density of mites is higher in bedrooms, with the highest number of mites in mattresses and sofas. Mites that breed on clothes may not pose a hazard to the human body, but clothes may be a means of spreading mites. As people move around, mites are transported to different places to live and reproduce.

Source: Chongqing Tianji Network Co., Ltd.

Source: This article is compiled from Live Science, Chronic Disease Prevention, Allergy Care Assistant, Thermo Fisher Allergen Detection, Healthy Hancheng, and Health News

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