Is Human 'Comfort' Also Optimal for Mites? Nearly 1 in 3 Risk Mite Outbreaks Due to Sensory-Based Humidity Management

Liberta Co., Ltd. (Headquarters: Shibuya-ku, Tokyo; Tokyo Stock Exchange Standard: 4935), which distributes products that 'plan joy and make the world interesting,' conducted a 'Mite and Season Awareness Survey' among 450 men and women in their 20s to 60s nationwide through its mite control brand 'Sayonara Danny.'

### Survey Summary - **Method:** Internet survey - **Date:** March 27, 2026 - **Participants:** 450 males and females aged 20-69 - **Area:** Nationwide

### Comments from Dr. Kimihiro Okubo, Nippon Medical School

**Keep humidity below 60% to reduce mite breeding** Mites breed easily from early summer when humidity rises, particularly during the rainy season. Therefore, it is crucial to keep indoor humidity below 60%. Areas like living rooms with carpets and closets require careful control.

**Sun-drying and ventilation are insufficient as primary measures** These common practices depend on good weather. However, in June, when mites start to increase, rainy days often prevent sufficient drying or ventilation. Furthermore, by summer, mites have already increased; drying only treats the carcasses, having limited effect on living populations. It is critical to suppress mite growth starting from June.

**Early prevention in June is key to reducing house dust allergies in September** While mites increase in June, the allergic reactions in our noses, eyes, and bronchi are caused by mite carcasses, which peak around the change of seasons in September. To prevent these symptoms, one must suppress the growth that starts in June. Since killing mites does not remove the carcasses or droppings (the actual allergens), it is also important to use repellents to keep mites away from prone areas.

### TOPIC 1 **84% recognize the relationship between humidity and mites, but the danger line for massive outbreaks is unknown** About 1 in 3 judge humidity management based on sensation, unaware of the indoor environment where mites multiply.

- **A 'Knowledge Gap' revealed:** While 84% answered 'humidity' as a condition for mite growth, the majority did not know the specific humidity guideline. Very few correctly understood that 60% or higher is the danger line. - **Sensory-based judgment:** When asked about acceptable indoor humidity during the rainy season, only 19% maintained it at 55% (where mites struggle to grow). About 1 in 3 responded that they judge based on 'how it feels.' Since humans feel comfortable between 40-60% humidity, environments that feel pleasant may actually be breeding grounds for mites if they hit that 60% threshold.

### TOPIC 2 **The mainstream of mite control is 'ventilation'...**