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EPA \ TAQMN \ Dust Storm \ Impact to Taiwan

Impact to Taiwan

The earliest record of east-Asian dust storm affecting the air quality of Taiwan can be traced back to April 12th to 15th of 1988 where air quality monitoring stations in north of Chiayi (including Hualian) recorded a rapid increases in the PM10 value, with the highest value reaching 201~422μgg/3 . When the mud rain phenomena occurred in northern Taiwan on March of 1995, the Wanli monitoring station recorded a PM10 density of 586μgg/3, and after analyzing the samples retrieved from the monitoring stations in Keelung and Hsichih it was discovered that the chemical content of these samples were similar to dust storm in east Asia, providing evidence to the source of these suspended micro particles.

When dust storm in east Asia begin to affect Taiwan, the air quality monitoring stations in northern Taiwan all detect a rapid increase of suspended micro particles in the air. For instance, the particle density in Matsu and Yang Ming Mountain are usually at levels of 20μgg/2 but increase to 150 to 200μgg/3 during dust storm, while the samples of particles gathered from the filter paper in the monitoring devices change from the usual black to a yellow brown.

As the effect of east-Asian dust storm on Taiwan's air quality is a macro area phenomenon, the high pressure cold front carries the dust storm south to monitoring stations in the mid and southern regions of Taiwan, which detect increases in particle density. The degree of increase is lower in the southern regions, but the affected regions can reach eastern regions such as Hualian, Taitung, and southern regions such as Hengchuen.

Dust Storm of February 16th, 1919
Dust Storm of February 16th, 1919

Future

Since establishing 66 air quality monitoring stations in 1993, the EPA has greatly strengthened Taiwan's abilities in observing the effects of air pollution due to long range sources. Recently, due to the ever increasing problem of deserts forming in China and others factors such as a global drought and uneven rain dispersion, there has been a rise in the frequency and strength of dust storm in east Asia. Statistics show that the recent number of times Taiwan's air quality has been affected by dust storm is 3 times in 2005 and 2006, 4 times in 2007 which caused 100 days, 92 days, and 70 days of air quality at the level of poor.

dust storm that form in the east Asia region which can affect Taiwan usually need 24 to 36 hours until they are able to travel with the northeast seasonal wind to affect Taiwan's air quality and visibility, with extreme cases causing weather phenomenon such as mud rain. However we must take into consideration the effects of weather conditions to truly understand whether Taiwan's air quality is caused by local weather or dust storm. Below is a combined analysis of the origin and movement of dust storm in comparison to the weather conditions of northern Taiwan in order to confirm whether Taiwan is being affected by dust storm.

When dust storm travel south through fronts and affect the air quality of Taiwan, the PM10 pollution density levels occur highest in the north, with levels decreasing as we move south and from the coast to in land regions. When dust storm are caused through high pressure backflow, the eastern regions of Yilan, Hualian, Taitung, and Hengchuen all clearly reflect an increase in micro particle density.

According to the strength of the dust storm, the density of micro particles decrease as you travel south but if the dust storm is weak, the affected area can be limited to mid Taiwan through different routes and in these cases the micro particle density levels in eastern monitoring stations are more apparent than the readings from western monitoring stations.

When the level of PM10 pollutant density rises, accompanying it is a rapid decrease in temperature and dew-point temperature (along with a decrease in humidity), wind speed increases as the dust storm travels to Taiwan with the cold and dry air.

When the dust storm travels from north to south, the trend in the increase of particle density is higher than usual due to the poor dispersion in these cases and the combined effects of the dust storm and local pollution. During periods of dust storm, the PM10 , PM2.5 densities increase with a heavier increase in the rough PM2.5~10 particles.

dust storm cause the particle make up of the air to change, with elements such as Al, Fe, Ca, Mg, and Mn having higher densities compared to normal, while sulfate and nitrate levels also change.

dust storm result in an increased number of particles, secondary micron-particles, and particles with a diameter of 10 microns. The number of secondary micron particles go from a single peak allocation during non-dust storm periods to a double peak allocation during dust storm periods.

In recent years with the more readily apparent transportation phenomenon of the northeast seasonal winds, the pollution from China's industrial regions can oftentimes drift to Taiwan. The dust storm on March 19th of 2006 brought high density sulfur dioxide (approximately 6 times the regular level).

last update : 2017/07/31

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