Smartphone Covers, Eco Bags, and Inside the Ears: A Comprehensive Guide to Tackling Hidden Mold During the Rainy Season

1. The Rainy Season and Mold: An Invisible Threat

Japan's rainy season brings an average humidity of around 80% and temperatures above 25°C, creating optimal conditions for mold growth. Mold spores can spread not only indoors but also on items carried outside and on the body's "hot and humid spots."news.ntv.co.jp

2. Mold Found on 40% of Smartphone Covers: Latest Survey Reveals Reality

Researcher Nobuo Hamada from the Osaka Museum of Natural History analyzed the smartphones of 116 street volunteers and found multiple types of mold on 48 devices (about 41%). The detection rate was higher among office workers in their 30s and older who frequently kept their phones in their pants pockets and had used the same cover for over two years.news.ntv.co.jp

• The Culprit: Sweat and Sebum: Humidity and nutrients accumulate in enclosed spaces

• The Blind Spot of Silicone and TPU: Softer materials retain moisture in gaps

• Smartphone Body Heat: Back temperature around 35°C accelerates mold growth
  
  
  
  

3. Mold Proliferation Mechanism: Smartphone Cover Edition

1. Sweat, Sebum, and Foundation Form a "Nutrient Layer"

2. Pocket Humidity Rises to 90% in 60 Minutes

3. Colonies Expand and Spores Disperse in 24-48 Hours

4. Inhalation Can Cause Bronchitis, Contact with Skin Can Cause Rashes
   
   
   
   

4. Immediate Measures for Smartphone Cover

5. Check Eco Bags Before Folding

Associate Professor Takashi Yaguchi from Chiba University's Medical Mycology Research Center warns, "If moisture or soil from vegetables remains, hyphae can grow within 24 hours." Fabric totes are particularly absorbent and slow to dry.news.ntv.co.jp


Washing Method

1. 2 liters of lukewarm water at 40℃ + 10g of oxygen-based bleach

2. Soak for 30 minutes, then gently rub with low water pressure

3. Turn inside out and dry in the shade (direct sunlight causes fabric deterioration)
   
   
   
   

6. What is "Ear Mold" Otomycosis?

According to Nishiogi ENT Clinic, about 10 people visit annually, with a concentration during the rainy season to summer. Typical symptoms include black earwax, hearing loss, and intense itching. Healing takes 3 weeks to several months.news.ntv.co.jpadachi-ent.or.jp

Risk Factors

• Excessive ear cleaning: Tiny wounds become entry points for fungi

• Using earphones for more than 1 hour continuously: Creates a high humidity environment in the ear canal

• Wet earwax type: Sebum + moisture make it easy for mold to settle
  
  
  

Earphone Usage Guidelines

Dr. Yukiko Matsuo recommends "For dry type = within 1 hour, 20 minutes ventilation" and "For wet type = switch to headphones as much as possible."news.ntv.co.jp

7. Self-Care to Protect Your Ears

• Clean ears once a month, use a cotton swab only up to 1cm inside

• After bathinguse a hair dryer's cool air for 10 seconds

• If discomfort persistsconsult a specialist—self-diagnosing with over-the-counter medication is prohibited
  
  
  
  

8. Lifestyle Checklist (Excerpt)

• □ Did you remove the smartphone cover and wipe the back this week?

• □ Have you washed your eco-bag within the last month?

• □ Are you removing your earphones every hour?

• □ Is the room hygrometer maintaining below 60%?
  
  
  
  

9. Expert Comment

"Mold is not an issue of 'appliances' or 'fabric products', but a problem of lifestyle itself. If you make washing, drying, and replacing a habit, you can definitely slow down the speed of mold growth."
— Nobuo Hamada, Visiting Researcher, Osaka City Museum of Natural Historynews.kantsuu.com

10. Summary

Mold lurking in "blind spots" like smartphone covers, eco-bags, and inside ears can be prevented with just a little effort. Systematize your cleanliness habits and enjoy refreshing days even during the rainy season.

List of Reference Articles

1. Nippon TV NEWS NNN "Carrying 'mold'? ... Prone to grow on smartphone covers and eco-bags" (June 11, 2025)news.ntv.co.jp

2. Nippon TV NEWS NNN "Some notice 'mold' with black earwax" (June 11, 2025)news.ntv.co.jp

3. Adachi ENT Clinic Column "What is Otomycosis?"adachi-ent.or.jp

4. Weekly Playboy NEWS "The Fear of Ear Mold from Earphone Moisture" (July 10, 2019)wpb.shueisha.co.jp

5. Osaka Museum Research "Smartphone-case mold survey" summary (2019)ddmap.jp