If the sky in Japan looks hazy, slightly yellow, or dusty—especially in spring—you’re probably seeing Kosa (Yellow Dust) or experiencing pollen season.

For travelers visiting Japan between February and May, this is something worth understanding.

🌫 What Is Kosa (Yellow Dust)?

Kosa is fine sand blown from desert regions in China and Mongolia. Strong winds carry it across East Asia, including Japan.

When Does It Happen?

Main season: February to May
Peak: March–April

Where in Japan?

Most noticeable in western Japan
- Kyushu
- Chugoku region
- Kansai region
Sometimes reaches:
- Chubu region (Nagoya area)
- Kanto region (Tokyo area)

What Does It Look Like?

Yellowish or beige sky
Distant buildings look blurry
Cars and balconies may get dusty
Sunset may look more orange than usual

🌲 What About Pollen?

Japan has a very intense cedar (sugi) and cypress (hinoki) pollen season.

After World War II, large areas were planted with cedar trees, and today they produce huge amounts of pollen every spring.

When Is Pollen Season?

Cedar (Sugi): February–April
Cypress (Hinoki): March–May

Where Is It Worst?

Nationwide problem
Particularly strong in:
- Kanto region
- Kansai region
- Chubu region

Even visitors with no allergy history sometimes experience symptoms in Japan.

🤧 Common Symptoms

Kosa

Scratchy throat
Eye irritation
Mild breathing discomfort

Pollen

Sneezing
Runny nose
Itchy eyes
Fatigue

If your eyes are itchy, it’s probably pollen.
If the sky looks yellow and visibility is low, it’s likely Kosa.
Sometimes, it’s both at the same time.

🛡 How to Protect Yourself

1️⃣ Wear a Mask

Masks are common in Japan and socially accepted.
They help reduce pollen and dust inhalation.

2️⃣ Check the Forecast

Search:

“Japan pollen forecast”
“Kosa forecast Japan”

Weather apps and local news provide daily updates.

3️⃣ Wash Face and Hands

After returning to your hotel:

Wash your face
Rinse your eyes
Change clothes if exposure was heavy

4️⃣ Keep Windows Closed

Especially on windy days.

5️⃣ Buy Allergy Medicine

Available at Japanese drugstores.
Look for “allergy” or ask staff for “kafun allergy medicine.”

Should Tourists Be Worried?

For most travelers, it’s uncomfortable—but not dangerous.

However, if you:

Have asthma
Have strong seasonal allergies
Are sensitive to air pollution

You may want to monitor air quality during your stay.

🌸 Final Tip for Spring Travelers

Spring is one of the most beautiful seasons in Japan—cherry blossoms, mild weather, and festivals.

But if the air looks hazy or yellow, now you know why.

It’s not fog.
It’s likely Kosa, pollen—or both.

Let us know when the cherry blossoms are blooming! What is Cherry Blossom Front?

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