What you need to know about allergies | Popular science time

Recently, Hohhot, Beijing and other places in Inner Mongolia ushered in thunderstorm weather, and at the same time, the number of emergency allergy patients in major hospitals increased sharply. Most patients develop allergy-induced asthma, which makes breathing difficult.

When people think of seasonal allergies, the first thing that comes to mind is spring allergies. Everyone takes it for granted that spring is the "king fried" of seasonal allergies. However, from a medical point of view, autumn allergies are a little more violent than spring.

Let's take a look at why.

Spring allergy VS autumn allergy

Spring allergens are mainly pollen, dust mites, etc., and autumn allergens are mainly pollen, dust mites, mold, etc. Although the "head" allergens in both seasons are pollen and dust mites, the two are very different.

Pollen allergens in spring are dominated by tree pollen. Autumn pollen allergens are dominated by weed pollen. In the crisp autumn weather, overgrown with weeds, the pollen of artemisia, humulus, ragweed, etc. with the advantage of small particles, with the help of dry air drifting wantonly, so that allergies come violently and unexpectedly. For allergic people, the air at this time seems to be "thorny", and going out is really feeling the "pain of breathing". Weeds bloom when the maximum temperature is below 30 degrees Celsius. These allergenic pollen are often transmitted by air movement, so when the air is dry and the relative humidity is lower than 50%, there are two or three wind conditions, which will be more suitable for weed pollen transmission.

In late summer and early autumn, humidity and temperature during the rainy season create good conditions for dust mites, especially house dust mites. The high temperature and humid environment in summer and autumn are very suitable for mold growth. So, the culprit of autumn allergies is mold.

Talk about thunderstorms and allergies

If spring pollen is a small witch, then autumn pollen is a big witch!

Although both tree pollen and grass pollen can cause pollen allergies, their degree of sensitization is not the same. Clinically, although the concentration of pollen in spring is higher than in autumn, grass pollen in autumn is more allergenic. For example, Artemisia annua, its pollen is the signature pollen of autumn, and it is very allergenic. Some people experience severe allergic reactions even if they are exposed to small amounts of pollen.

Autumn pollen particles are small and light, and can float hundreds of kilometers with the wind, and even fly at altitudes of tens of thousands of meters. Pollen rises to the bottom of the cloud with the air flow, and the moisture and static electricity of the cloud make the pollen particles "burst"! This is why the stormy weather of autumn makes pollen "burst", creating thunderstorm allergies. One pollen "burst" can release 700 subpollen particles! The strong cold air descends, bringing more and lighter subpollen particles back to the ground and into the human airways. Subpollen particles are more allergenic, more comfortable in the human body, and the harm caused is more serious! This brings the allergenicity of autumn pollen to another level.

There is such data for reference: the probability of spring pollen allergy causing asthma is only 5%, while summer and autumn allergy patients have more severe symptoms, and 50% of patients may develop asthma.

Another reason for the high incidence of allergies

Another reason for the high incidence of allergies in autumn is that autumn weather is drier, ultraviolet rays are more intense, and climate changes are more frequent than spring. In autumn, the humidity of the air decreases, and the moisture content of the stratum corneum of human skin also plummets. When the temperature decreases, the sebaceous glands of the skin secrete less and less oil, and the skin's ability to lock in water is also reduced. When the cool autumn breeze blows, taking away more moisture from the skin, the skin barrier becomes more fragile. Once exposed to the allergen of fine particles, a skin allergic reaction occurs, causing symptoms such as itching, redness, and pimples to follow.

The most common occurrence of skin allergies in autumn is allergic dermatitis, facial dermatitis, ultraviolet allergy, cold air allergy, etc. Cold air allergy is actually a special rhinitis - vasomotor rhinitis. It is manifested as sensitivity to temperature changes, and hot and cold air stimulation can cause obvious runny nose and sneezing. The symptoms are the same as allergic rhinitis. But allergic rhinitis is an allergy to a substance that does not cause symptoms as long as there is no contact with the allergen. Vasomotor rhinitis is a protective reaction that occurs because the body's vasomotor function cannot keep up with changes in air temperature.

There are also symptoms that seem unrelated to allergies, but are actually caused by allergies. For example, headache is caused by turbinate hypertrophy and mucosal edema that stimulates nasal nerves. There is also an itchy throat because the allergen is irritating the mucous membrane of the throat. Facial puffiness is also caused by facial allergies and obstruction of lymphatic return.


There are some tips in daily life that can help everyone prevent allergies in the fall.

1. Pay attention to a healthy diet and avoid excessive intake of irritating foods and allergenic foods.

2. Pay attention to indoor air quality and humidity, and use humidifiers if necessary.

3. Stick to proper exercise and ensure adequate sleep.

4. Clean the home environment regularly, often cleaning the places where dust mites and pollen gather.

Author: Zhou Weikang, expert of the National Health Science Expert Database and chief physician of the Department of Allergy of Chongqing Municipal People's Hospital

(Health China WeChat public account)