Suitable temperature and humidity for respiratory diseases

Based on domestic respiratory clinical guidelines, public health research data and front-line diagnosis and treatment experience, for respiratory disease patients and susceptible groups such as the elderly and children, maintaining indoor temperature at 18~24°C and relative humidity at 40%~60% is currently recognized as an appropriate range that can minimize respiratory tract irritation and reduce recurrence of illness.

Last week at the community respiratory follow-up clinic, I met Uncle Zhang, who had been suffering from COPD for 3 years. He had just been discharged from the hospital last month due to an acute attack. He turned on the heater to 28°C for fear of being cold at home, and he was also afraid of dryness and left the humidifier on 24 hours a day. Within a week, he came back for a follow-up consultation with coughing and panting. The indoor humidity in his home was measured to be 78%. The temperature was so high that he only wore single clothes at home. When he opened the door, a cold breeze directly irritated his respiratory tract. Coupled with the mold that grows in high humidity, the disease relapsed.

Let’s first talk about why the temperature is stuck at 18 to 24°C. Our respiratory mucosa is very delicate. If the temperature is lower than 18°C, inhaling cold air will directly stimulate the contraction of the mucosa. The already inflamed respiratory tract will tighten instantly, and symptoms of coughing and asthma will come up immediately. This is especially true for people with asthma and chronic bronchitis. Oh, yes, not everyone agrees with this range. For example, many doctors in the field of pediatrics will recommend that the room of a baby of one month old can be adjusted to 20~26°C. After all, children have weak body temperature regulation ability. If they are too cold, they will easily catch a cold, and if they are too hot, they will easily develop heat rash. This difference is essentially due to the different tolerances of people. There is no right or wrong.

After talking about temperature, let’s talk about humidity, which is more likely to be ignored. The range of 40% to 60% is actually a compromise between the demands of several different departments. The Department of Respiratory Medicine assumes that under this humidity, the respiratory mucosa will not be dehydrated, and the small broom-like cilia on the surface can swing normally, sweeping out the inhaled dust, viruses, and sputum. If the humidity is lower than 30%, these small cilia will become unable to move. Not only will the throat be dry and painful, but pathogens will also easily take root in the mucous membrane. Colds will heal slowly, and secondary bacterial infections may easily occur.

However, this value is not absolute. Many allergy doctors will recommend that patients with dust mite and mold allergies keep the humidity between 40% and 50%. After all, dust mites will multiply several times in an environment with a humidity higher than 55%, and molds prefer humid places. If you are a patient with allergic rhinitis or allergic asthma, too high humidity will easily induce allergic attacks, which is not worth the gain.

A little girl with allergic asthma that I followed up before had two thermometers and hygrometers specially installed at home, one in the living room and one in the bedroom. In spring and autumn, the humidity was just right, so no additional adjustments were needed. In winter, when the heating was turned on, a small humidifier was turned on, purified water was changed every day, and the humidifier water tank was washed once a week. The humidity was stuck at around 45%. She had almost no asthma attacks in the past six months. Her mother would turn on a dehumidifier when she returned to the south or during the rainy season, otherwise mold would grow on the walls of the house and she would cough whenever she breathed in.

There is no need to hold a thermometer and hygrometer to get stuck on the value. After all, everyone's physical sensation is very different. I have seen some young people who are afraid of heat when they catch a cold in winter. The room temperature is 24℃ and they still feel stuffy.

Oh, by the way, there is another pitfall that many people step on: don’t overheat the indoors in winter. If you wear a single layer at home and a thick down jacket when going out, the temperature difference of more than ten degrees will hit your face. The contraction and expansion of the respiratory tract will make it more likely to cause problems. It is best to wear a thin sweater or velvet home clothes when the indoor temperature is just right. Adding a coat when going out will not make you feel the difference between hot and cold. It will be more secure.

In fact, for patients with respiratory diseases, temperature and humidity are only part of auxiliary care. The key points are to reduce exposure to irritating gases, quit smoking, and take medications as prescribed by the doctor. Just adjusting the temperature and humidity to an appropriate range can avoid a lot of unnecessary sins. Why not do it?