The short answer: Asian dust is soil dust, fine dust is dust you breathe in
Asian dust and fine dust are not two names for the same thing. According to the Gangnam-gu card news, Asian dust is dust with a high share of soil components such as silicon, while fine dust contains large amounts of sulfates and nitrates. Asian dust forms mainly in northern China, the Mongolian desert regions and the Loess Plateau; fine dust comes mainly from human activity. The two can be seen as differing in composition and in where they come from.
By particle size alone, the two look much alike. The Gangnam-gu card news puts Asian dust particles at 5–8 μm, and among fine dust, PM-10 means dust 10 μm or less in diameter. On the numbers alone, Asian dust falls inside that range, so it can be said that size alone is a hard dividing line to draw. The proportions in which the two mix in the air cannot be confirmed from the sources used here.
How the Gangnam-gu card news defines fine dust, PM-10 and PM-2.5
The Gangnam-gu card news starts with a definition: dust is particulate matter that floats in the air or scatters and settles back down, and fine dust is the portion of that dust inhaled through the nose or mouth. Two conditions underlie that definition. The material has to be particulate matter suspended in the air, and it has to enter through the nose or mouth.
The same material sorts fine dust into two categories. The line describing fine dust particles reads: "dust, pollen, mold and the like, 10 μm or less in diameter." That is PM-10. The line describing ultrafine particles reads: "combustion particles, organic compounds, metals and the like, 2.5 μm or less in diameter." That is PM-2.5. The two lines cite different examples of material.
Asian dust at 5–8 μm: separated by origin and composition
The Gangnam-gu card news sums up the relationship in a single sentence. Its section on Asian dust states: "Asian dust particles are 5–8 μm in size, similar to fine dust, but on closer inspection there are differences in origin, composition and so on." The sentence notes the similarity in size first, then points to origin and composition as the distinguishing criteria. So the dividing line between the two can be seen as composition and source region rather than size.
Set the categories side by side. In size, Asian dust measures 5–8 μm, while PM-10 is 10 μm or less in diameter and PM-2.5 is 2.5 μm or less. In composition, Asian dust has a high share of soil components such as silicon, whereas fine dust contains large amounts of sulfates and nitrates. The sources differ too: Asian dust comes from northern China, the Mongolian desert regions and the Loess Plateau, and fine dust comes mainly from human activity.
Health effects of fine dust and flexible hours for sensitive groups
The Gangnam-gu card news also covers health effects. Fine dust particles are small enough to slip past the filtering action of the nose, mouth and bronchial tubes, and they can seep deep into the body. Long exposure can trigger asthma, lung disease, cardiovascular disease and other illnesses, which is why the material urges caution. No separate figures for the health effects of Asian dust particles can be confirmed in this material.
The same material also covers what to do. On days when fine dust is heavy, the government recommends flexible working hours for pregnant women, people with respiratory illness and other sensitive groups — a recommendation aimed at cutting exposure time. Real-time concentrations and forecasts can also be checked by phone: AirKorea lists the Weather Call Center at 131 for questions about real-time fine dust levels and forecasts. The number is listed as a paid call.
The KMA's Asian dust observation days and AirKorea's country-by-country guide to the data
The Korea Meteorological Administration publishes Asian dust observation days station by station, with monthly columns running from January through December. For the Seoul station in 2001, the table shows 1 day in January, 11 in March, 9 in April, 4 in May and 2 in December, and dots instead of numbers in the remaining months. Judging by that single year, observation days cluster in March and April, though there are records in January and December as well.
AirKorea lists Asian dust websites by country. For Korea it lists the meteorological sector's Asian Dust Center; for Japan, the Japan Meteorological Agency's dust measurement data. The National Institute for Environmental Studies of Japan provides Lidar data covering Korea, Mongolia and Japan, and the same institute's CFORS forecasts Asian dust and anthropogenic pollutants across East Asia. For China, the China Meteorological Administration's international weather center provides data on changes in surface concentrations during sand storms, and the State Environmental Protection Administration (SEPA) provides air pollution index data for 47 Chinese cities.
American sources appear on the list as well. The U.S. National Oceanic and Atmospheric Administration's ARL provides Hysplit, a back-trajectory analysis tool — a name that reads as meaning a method of retracing the path air has traveled. Readers who want the original materials have two places to go: the table of Asian dust observation days on the KMA website, and the country-by-country list in AirKorea's guide to Asian dust websites.
In summary
Asian dust and fine dust are similar in size but different in composition. The Gangnam-gu card news describes Asian dust as dust with a high share of soil components such as silicon, and fine dust as dust containing large amounts of sulfates and nitrates. Asian dust particles measure 5–8 μm, PM-10 is 10 μm or less in diameter and PM-2.5 is 2.5 μm or less. So it can be said that one number alone is not enough to treat the two as the same thing.
When reading the data, match the agency to the specific category first. The KMA provides monthly Asian dust observation days by station, and AirKorea lists Asian dust websites for Korea, Japan, China and the United States. Questions about fine dust concentrations and forecasts go to the Weather Call Center at 131. Causes or trends beyond the scope of this article cannot be confirmed from the sources used here.
