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Size and sources
2.5 micrometres equals 0.0025 millimetres. Sources include combustion, particles formed by reactions in air, fires and natural material. Sources may be local or distant.
Short-term symptoms and long-term risk
Exposure may aggravate respiratory symptoms and affect the heart and lungs. Longer-term exposure is associated with chronic respiratory and cardiovascular disease and lung cancer. A cough today does not predict a person’s future disease.
Relationship to dust and haze
Some yellow dust and smoke particles belong to PM2.5. Haze is an appearance of the air and does not determine the measured concentration.
Two different benchmarks in Japan
The environmental standard is an annual mean of 15 µg/m³ or lower and a daily mean of 35 µg/m³ or lower. The provisional public advisory guideline is a daily mean of 70 µg/m³. These are different purposes, not individual diagnostic thresholds. Do not compare an hourly value as if it were a daily mean.
Outdoor and indoor precautions
On high-pollution days adjust prolonged strenuous outdoor activity. A well-fitting particulate respirator may help but cannot remove gases. Use a suitable air cleaner, avoid indoor smoke and maintain necessary ventilation and safe temperatures.
People who need extra care
Children, pregnant people, older adults and those with heart or lung disease should reduce exposure and discuss symptoms with their clinician. Do not change prescribed medication on your own.
Air-quality information in Fukuoka
Fukuoka forecasts and official advisories and monitoring links (Japanese). Check the place and time; forecasts and measurements are different.
When to seek care
Contact an ENT clinic for persistent nose or throat symptoms or cough. We assess the history and examine the nose and throat; tests and treatment depend on findings. Other causes, including infection and asthma, must be considered. Referral to internal or respiratory medicine may be needed.
Call 119 for severe breathing difficulty, chest pain, blue lips or altered consciousness. Do not assume these are due to air pollution. Sublingual immunotherapy is not provided at this clinic.
Frequently asked questions
Does an air cleaner replace ventilation?
No. Particle filtration does not remove carbon dioxide or all gases. Necessary ventilation and temperature control remain important.
Related guides
Visiting Honda ENT Clinic
Check temporary changes
| Day | Morning | Afternoon |
|---|---|---|
| Mon / Tue / Wed / Fri | 9:00–12:30 | 15:00–18:20 |
| Saturday | 9:00–11:00 | 14:00–16:00 |
| Closed | Thursday, Sunday and public holidays | |
Reception opens 15 minutes before each session. Walk-ins are welcome for general consultations. Vaccinations may require an appointment.
Please call before visiting if you have a fever of 37.5°C or higher, a recent positive infection test, a household member with an infection, or would like infection testing. The waiting-time service is in Japanese.
Schedules can change. Check clinic news or call before travelling.
References and information management
Published by Honda ENT Clinic. Content management: Medical Director Dr. Yusuke Honda. Reference checking and editing: website administration. Updated: 18 October 2026.
General information; individual diagnosis and treatment require clinical assessment.