According to Dr. Nguyen Huu Truong, Deputy Director of the Center for Allergy and Clinical Immunology at Bach Mai Hospital, closed, humid environments with poor air circulation create ideal conditions for mold and house dust mites to thrive - especially inside air-conditioning systems that are not cleaned regularly.

The hidden trap inside air-conditioned rooms

During peak heat waves, many people spend long hours in heavily air-conditioned spaces with low temperatures. However, Dr. Nguyen Huu Truong warns that poorly maintained air conditioners can become a source of harmful allergen exposure.

“An air conditioner that is not cleaned and serviced regularly can act like a machine blowing mold spores directly into people’s noses and lungs,” the doctor warned.

Beyond cooling the air, dirty air conditioners may also circulate fine dust particles containing dust mites and microscopic fungi - common triggers of allergic reactions in sensitive individuals.

Your body may already be sending warning signals

Experts say allergies caused by mold and house dust mites often develop silently and are easily overlooked. People should pay attention to symptoms such as:

Itchy, red, irritated eyes despite adequate rest and limited screen exposure;
Sneezing, itchy nose, runny nose, or nasal congestion that appears when the air conditioner is on but improves noticeably outdoors;
Skin rashes, itching, or hives without exposure to unusual foods, medications, or cosmetics;
Persistent dry cough, wheezing, or shortness of breath in enclosed spaces.
“If these symptoms repeatedly occur in air-conditioned environments, the body may be reacting to airborne allergens,” Dr. Nguyen Huu Truong explained.

How to protect your respiratory system during hot weather

Based on clinical experience, Dr. Nguyen Huu Truong recommends several preventive measures to reduce the risk of allergies and respiratory problems:

Clean air conditioners regularly: Do not wait until filters are visibly covered with dust. Air-conditioning systems should be cleaned periodically to remove accumulated dirt and mold;
Improve ventilation: Avoid staying in sealed rooms for many consecutive hours. Open windows at the end of the day or during weekends to allow sunlight and fresh air inside;
Use damp cloths for cleaning: Wipe surfaces with a damp cloth instead of dry dusters or feather brushes, which can disperse dust and mold spores into the air.
Dr. Nguyen Huu Truong emphasized that people should not ignore persistent allergy symptoms.

“If sneezing, nasal irritation, wheezing, or skin rashes recur frequently, people should seek medical evaluation at specialized healthcare facilities as early as possible for timely diagnosis and treatment. Delayed treatment may allow the condition to become chronic and more difficult to manage later,” he advised.