Hong Kong residents are facing a period of high humidity, with real-time sensors across the city recording dangerous relative humidity (RH) levels between 82-90%, according to the Hong Kong Observatory (HKO). Although often dismissed as merely uncomfortable, the high humidity levels present a weather phenomenon that poses serious health risks demanding attention.
“It’s Not Only Uncomfortable”
This is not just unpleasant weather—it’s a physiological threat. According to the World Health Organization (WHO), human health is compromised when humidity exceeds 65%. At levels above 85%, the body’s natural cooling system begins to fail and the respiration system faces higher pressure.
“At 90% humidity, sweat literally can’t evaporate,” explained Dr. Joanna Joeng, a physician at Queen Mary Hospital. “It’s like wrapping yourself in a plastic bag while still generating heat.”
The excessive moisture in the air also makes breathing more difficult. “Simply put, damp air is denser and heavier, forcing the lungs to work harder,” added Dr. Joeng. Meanwhile, the elderly and those with existing respiratory issues are more vulnerable and more likely to experience breathing emergencies. She noted that there was approximately a 50% increase in asthma-related ER visits his week compared to last week.
The Mold Invasion
Another consequence of prolonged high humidity is the uncontrollable growth of mold. “They (molds) are all over my apartment—my walls, my closets, even my leather coat,” Laurence Mo, an engineering student at HKU, complained with a deep sigh. “I’ve already thrown away three pairs of shoes.”
Mold is not just unsightly, it poses serious health risks. “Mold spores can easily enter the respiratory system and cause infections,” warned Dr. Joeng.
How to Protect Yourself
Dr. Joeng has suggested several steps for Hong Kong residents to cope with the high-humidity situation:
Make good use of your windows – “Certain times during the day have the lowest humidity levels. Opening windows during those periods and closing them when humidity rises is the best way to reduce dampness,” said Dr. Joeng . She also noted that these low-humidity periods often coincide with strong winds.
Avoid going out – Staying indoors can effectively minimize exposure to high outdoor humidity. “Walls and buildings are our most powerful tools to block out dampness,” noted Dr. Joeng.
Hong Kong’s Humidity Problem Persists
Hong Kong and Southern China have long experienced the high humidity problem. They even have a special term for it: “Wui Naam Tin” (Returning South Days). Hong Kong’s high humidity stems from its coastal location, mountainous terrain that traps moist air, dense urban development, and seasonal monsoon rains, according to Yang Haiyu, a geography PhD student in HKU.
Despite Hong Kong’s already high humidity levels, experts warns they may increase during this period. Climate change is exacerbating the issue with rising sea temperatures increasing evaporation, which would lead to even higher humidity levels.
“People underestimate the severity of high humidity,” said Yang. “Mold and dampness are not just internet jokes—they’re not paid enough attention.”