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進入《TAIPEI TIMES》 Yunlin County ranks first in Taiwan for PM2.5
Yunlin County is shrouded in a haze in an undated photograph. Photo: Chan Shih-hung, Taipei Times
/ Staff writer, with CNA
Yunlin County had the nation’s highest annual average concentration of airborne particles measuring 2.5 micrometers （PM2.5） or less last year, data from the Ministry of Environment showed.
The county recorded an average PM2.5 concentration of 19.3 micrograms per cubic meter （mcg/m3）, followed by nearby Chiayi County and Chiayi City, as well as outlying Kinmen, all at 18.8mcg/m3, the data showed.
Taiwan hopes to lower its annual average PM2.5 level to less than 13mcg/m3 and the annual average PM2.5 concentration in central and southern Taiwan to less than 15mcg/m3 by 2027, the ministry said.
Department of Atmospheric Environment head Chang Shun-chin （張順欽） said that a higher PM2.5 level in central and southern Taiwan was mainly a result of less rain and low wind speeds there.
Those conditions led to particulate matter not being able to diffuse into the air, resulting in the local accumulation of pollutants, he said.
In terms of the annual average concentration of nitrogen dioxide, data showed that Taipei led the nation with 13.87 parts per billion （ppb）, followed by Kaohsiung at 11.49ppb.
Areas such as New Taipei City, Taoyuan, Hsinchu City and Taichung also recorded relatively high levels.
Mobile sources of pollution and topography greatly contributed to the situation, Chang said.
For example, in Taipei, a high number of vehicles, coupled with its basin topography and poor dispersion, resulted in higher nitrogen dioxide concentrations.
Additionally, as nitrogen dioxide is a precursor to ozone, the overall ozone concentrations in the western part of Taiwan — where those cities are located — are also higher than those in the east, he said.
The data also showed the status of other major pollutants, such as PM10, an indicator of airborne particles measuring 10 micrometers or less. Yunlin County’s annual average was the highest （41.5mcg/m3）, followed by Changhua County （40.8mcg/m3） and Chiayi County （40.2mcg/m3）.
These values were below the annual average of 50mcg/m3 set by the ministry.
新聞來源：TAIPEI TIMES
