June in the north began to enter the hot summer, rain gradually more up. In this hot and humid season, we all have similar experience: food and clothing stored improperly will be “hairy”, moldy spots. And then pay close attention to the surrounding, we can find that many people will be sneezing, runny, itchy eyes, and even coughing and wheezing symptoms during this time. Why is this? If we look into the root cause, let’s first understand what is fungus. Fungi are the most widely distributed class of organisms in nature, with an estimated variety of nearly one million species, which can be roughly divided into two categories: yeasts and molds. Fungi and human life is closely related to the daily consumption of mushrooms, fungus, Chinese medicine, Lingzhi, Poria, brewing, flour with yeast, the production of penicillin penicillin, these are fungi. Most of the fungi camp saprophytic, a few can be parasitic in the body of humans or animals. Fungal reproduction requires high temperature and humidity. In the south of China’s rainy season, the northern wheat harvest before and after the temperature and humidity are very suitable for fungal growth, is the peak season of fungal reproduction. Airborne fungi are referred to as airborne fungi and are one of the most common and important inhalant allergens. Outdoor airborne fungal allergens are mainly spores, while indoor fungal allergens and those present in the body are mainly mycelium. Airborne fungi can act on the nasal mucosa and conjunctiva of the allergic organism, resulting in allergic symptoms such as sneezing, runny nose and itchy eyes. In addition, the spores of airborne fungi are very small, only a few microns in diameter, so they can not only float in the air for a long time, but also can be inhaled deep into the lungs more easily to cause asthma symptoms such as coughing and wheezing. Outdoor fungi (such as Streptomyces interrogans) are significantly affected by climate and environmental factors. The number of airborne fungal spores is highest in humid and hot seasons, in environments with large vegetation and dirty areas. Rain can cause a sudden decrease in the number of spores in the air, but after the rain clears, the number of spores in the air increases significantly again. Therefore, the condition of fungal allergy patients can be seasonal and fluctuating. Outdoor fungi can also enter the house through ventilation, so patients with severe allergies are advised to stay indoors and keep doors and windows closed as much as possible during the onset season. Indoor fungi (such as Aspergillus fumigatus and Penicillium) often grow in humid indoor environments, such as basements, kitchens, and bathrooms, and can induce the appearance of perennial allergy symptoms. The reasonable use of air conditioners can inhibit the growth of fungi in the indoor environment by reducing humidity, but if cleaning is not thorough, the air conditioner indoor unit itself will become a source of fungal growth and dispersal. Excessive use of humidifiers in winter and spring, and their sink cleaning is not timely, can contribute to the growth of fungi. The symptoms of fungal allergy can be reduced or even prevented by avoiding carpeting in the living room, cleaning the house regularly, keeping the bathroom and kitchen ventilated and dry, and using air purifiers with high efficiency particulate air (HEPA) cartridges if necessary. If fungal allergy patients cannot effectively control their symptoms through daily precautions, they need to visit a hospital and be treated with targeted medication by a specialist according to the extent of the disease. Patients who are not satisfied with drug control can receive specific allergen immunotherapy (also known as desensitization), and most patients can obtain long-term, stable treatment results after 3-5 years of treatment.