Along with the prevalence of spring-time pollen, there's another annual annoyance that often affects Japan, known as "yellow sand", "Asian dust", "yellow dust", or a more official term, Aeolian Dust, and in Japanese as 黄砂 (こうさ, kousa). This dust is stirred up by the wind from deserts in Mongolia, northern China and Kazakhstan, and carried in clouds over China, North and South Korea, and Japan.
Seems relatively harmless, but this dust has also been found to carry a variety of toxic particles, such as heavy metals, sulfur, viruses and bacteria, asbestos, and other pollutants. As far as I've been able to find, Japan doesn't seem to have experienced many health problems due to this dust (please correct me if you know otherwise), though South Korea has reported adverse health effects, particularly in those with respiratory problems. The dust can also decrease visibility, stain laundry, and cause other problems.
Just to clarify, this isn't necessarily something you need to worry about on a daily basis during spring, but it might be good to be aware of for when it does occur, particularly if you live in Okinawa, Kyushu, Chugoku or Kansai (though it can apply to other regions). If it does appear in significant amounts, you may want to think about hanging your laundry indoors and possibly wearing a mask outside, especially if you have allergies and/or respiratory problems. I'm not a medical expert, so definitely look up "Aeolian Dust" and "health effects" so you can gain a better idea about how it might affect your health.
The U.S. Consulate of Naha (Okinawa) issued this statement on April 28, 2011 about dealing with Aeolian dust, particularly if you have health issues:
If you suffer from allergies or have a pre-existing respiratory problem such as asthma, emphysema or other forms of chronic respiratory disease you may want to consider limiting outdoor activities when high dust levels are present.
- Wear glasses instead of contacts
- Close windows
- Wash exposed skin after returning indoors
- Wear long sleeves
- Cover mouth and nose
- Do not drink or eat food outside
- Drink water frequently
- People with lung disease, older adults, and children should avoid prolonged or heavy exertion
Now, I want to introduce to you two tools you can use to determine the levels of "yellow sand" in your area on any given day, and also how to look at predictions.
1. Japan Meteorological Agency
JMA offers a map that presents visibility measures from different weather stations around Japan (and southeast Asia). Those this won't give you a measurement of actual levels, the less visibility you have, in general, according to this map, the higher the amount of yellow dust. The key is in English, but red would be the color to worry about the most, with blue or white being the least.
|Levels as of 18:00 Japan standard time on May 2, 2011|
|Predicted levels for 21:00 JST on May 2, 2011|
2. LIDAR DSS [Dust and Sandstorm] Observation Data Page
This site has a map of Japan and part of southeast Asia, with either blocks or cylinders at certain cities to represent the current dust levels in the air up to 6 kilometers. The taller the cylinder, the higher the levels of yellow sand. If only a small blue block, then very little or none has been measured (or reported).
If you click on the cylinder, the levels will be displayed between 0 and 6 kilometers (altitude), with the color red representing a higher concentration. Click on the city name for hourly measurements and daily averages from the past seven days. And finally, if a cute little panda is peeking out from behind a cylinder, this means DSS levels close to the ground are very high (which is when you might want to take precautions). Feel free to browse around the site for more useful info in English.
|Levels as of 20:00 JST, May 2, 2011|