TAIPEI, Taiwan - Taiwan's first sandstorm in five years hit the island yesterday along with a continental cold front, sending ambient air quality plummeting nationwide.
Matsu County was the first to be affected, with monitors reporting coarse particulate matter (PM10) and fine particles (PM2.5) in excess of daily limits yesterday morning.
In Greater Kaohsiung, the air quality index (PSI) flashed purple for "very unhealthful," mainly due to poor air dispersion in the region, said the Environmental Protection Administration (EPA).
The sandstorm originated in China's Inner Mongolia on March 2 and was brought south to Taiwan by a continental cold front.
The last time a sandstorm hit Taiwan was in March 2010, when loose grit and dust - also originating from Inner Mongolia - impacted air quality in Taiwan for more than 10 days.
Poor Air Quality to Linger
Northern Taiwan was clothed in gray due to the double impact of rain and sandstorm effects.
Rainfall mitigated the sandstorm's early effects by dissolving some of the airborne pollutants, said Chang Shun-chin, deputy director of the EPA's Department of Environmental Monitoring and Information Management.
The sandstorm should weaken in northern Taiwan by tomorrow, though air quality is not expected to improve due to poor diffusion conditions in central and southern Taiwan, Chang said.
The EPA's air pollution index measures air quality in terms of how much suspended dust, soot, carbon monoxide, sulfur dioxide and ozone is in ambient air.
An index of between 101 and 199 is graded "unhealthful," while an index between 200 and 299 is "very unhealthful" and a rating over 300 is "hazardous."
Shortly after 10 a.m. in Matsu County, readings for coarse particulate matter exceeded 126 micrograms per cubic meter, while readings for PM2.5 reached 74 micrograms per cubic meter.
The figures translate to a PSI index of "very unhealthful."
Parts of Southern Taiwan - including Zuoying), Renwu, Siaogang and Cianjhen districts - reached a PSI index of "very unhealthful" due to poor air diffusion, Chang said.
In Yunlin County, Chiayi County and Tainan, air quality began deteriorating around noon yesterday.
Moderate precipitation in Keelung yesterday resulted in comparatively better air quality, but in Wanli District of New Taipei City, Guanyin District in Greater Taoyuan and Guting in Taipei, the PSI index approached 100.