An air quality monitoring station at National Central University (NCU) has become an index station for NASA’s regional measurements due to the accuracy of its data, the university said yesterday.
The station uses micropulse lidar to determine the source of air pollutants, by measuring changes in wave forms when they are bounced back by atmospheric particulate matter, the university said.
Chang Shuenn-chin (張順欽), director-general of the Environmental Protection Administration’s (EPA) Department of Environmental Monitoring and Information Management, said the station has overcome the challenge of determining pollutant sources, which had plagued EPA officials before.
“Although ground-level sensors can tell you about the special characteristics of pollutants in a particular area, they cannot tell you the direction particles fall in or how they disperse,” he said.
The EPA started using micropulse lidar technology from NASA in 2002, when it began long-term monitoring of particle dispersal.
The data it collected allowed it to analyze air pollution patterns and concentrations, and to gain a more accurate understanding of air quality changes, Chang said.
The micropulse lidar system can gather readings from as high as 30km in the atmosphere, at a vertical resolution of 75m, and gathers information 24 hours a day, he said.
“If the wave forms of backscattered electrons it detects are irregular, it has likely detected elements from the Earth’s crust, for example from a sandstorm,” he said.
“Globular wave forms likely indicate pollutants produced by high-temperature combustion,” he said.
NASA has collected atmospheric data in this manner since 2000 through the US federated Micro-Pulse Lidar Network (MPLNET), university assistant professor Wang Sheng-hsiang (王聖翔) said.
The network collects data from around the world, and is able to analyze the environmental effect of smog and sandstorms in China, as well as from the slash-and-burn agricultural practices employed in Indochina, he said.
MPLNET comprises 26 monitoring stations worldwide, four of which are in Taiwan. Taiwan’s stations are at the National Central University in Taoyuan, as well as in Taichung’s Situn District (西屯), Yunlin County’s Douliou City (斗六) and Kaohsiung’s Zuoying District (左營).
The university’s station was added to MPLNET due to the maintenance of its equipment and the reliability of its data, Wang said.
“The university’s system is in a temperature and humidity-controlled environment, and the lens is cleaned even more frequently than those at US monitoring stations,” he said.
Cooperation with NASA on MPLNET is important given the global interest in tackling air pollution and improving air quality, Chang said.
Air quality can be affected by natural or synthetic phenomena, he said.
Examples of the former include sandstorms, volcanic activity, sea spray, forest fires and the erosion of geological formations, while sources of synthetic pollutants include factories, motor vehicles, construction and farming, Chang said.
Air pollutants include particles with a diameter of up to 10 micrometers and those with a diameter of up to 2 micrometers, ozone, vulcanized materials, nitrogen oxide, carbon monoxide and lead.
The EPA measures air pollution nationwide at 111 monitoring stations, which include 77 standard monitoring stations, 10 mobile stations and other facilities that take measurements using light and other methods.
The stations have measured decreases in most pollutants in the past few years, but have shown annual increases in the concentration of ground-level ozone, which can cause breathing difficulties and chest pain, the EPA said.
Air quality in Taiwan is affected by seasonal winds and geography, Chang said.
“Strong northeasterly winds blow between October and April, bringing pollutants from China,” he said, adding that the central mountain chain then weakens the wind, so that pollutants become trapped above central and southern Taiwan.
However, southwesterly winds that blow between May and September bring stronger winds to central and southern Taiwan, so air quality in those regions improves, he said.
Meanwhile, air quality is worse during the day due to human activity, with pollutants reaching peak concentrations at about 6am and 6pm due to heavy traffic, he said.
Also, concentrations of nitrogen oxide and carbon monoxide are on average 1.2 times higher during work days than on weekends, he said, adding that concentrations are 1.7 times higher during rush hour.
Meanwhile, Chang said that the best time to jog outdoors is between 4am and 7am.
GREATER NUMBER: The sorties might have been a response to the US and the EU expressing concern on Friday over China’s ‘provocations’ in the Taiwan Strait Twenty-five Chinese military aircraft and four naval ships were detected around Taiwan from 6am Saturday to 6am yesterday, including eight airplanes that had crossed the median line of the Taiwan Strait and another two that entered Taiwan’s air defense identification zone (ADIZ). The People’s Liberation Army (PLA) aircraft that entered Taiwan’s southwestern ADIZ were a Y-8 anti-submarine plane and a BZK-005 uncrewed aerial vehicle, the Ministry of National Defense said. The aircraft that flew across the median line include two Sukhoi Su-30 fighter jets, four J-16 multipurpose fighters and two J-10 jets, the ministry’s official Web site showed. Taiwan’s armed forces monitored the
Mask easing: Teachers are allowed to take their masks off while lecturing indoors, but students should keep theirs on, as COVID-19 measures ease this week The Ministry of Education (MOE) yesterday released new on-campus COVID-19 prevention guidelines, stating that masks can be taken off while exercising, singing, dancing, performing, taking photographs, dining, drinking, video and voice recording, hosting events, presenting speeches and lecturing outdoors. Large outdoor events organized by schools should comply with the mask regulations issued by the Central Epidemic Command Center (CECC), it added. The new guidelines came into effect yesterday, and people in Taiwan are no longer required to wear masks outdoors for the first time since May 19 last year. The CECC announced the easing of the mask mandate on Monday, adding that it
LUNAR NEW YEAR PEAK: Taiwanese who are in China should get vaccinated and consider returning early, as infection rates are expected to increase, the CECC said China faces five major problems once COVID-19 begins spreading there, with a peak in infections likely during the Lunar New Year holidays, Deputy Minister of Health and Welfare Victor Wang (王必勝), who heads the Central Epidemic Command Center (CECC), said yesterday. Wang wrote on Facebook that according to the center’s data, the increasing number of COVID-19 cases in China is worth noting, as the new Omicron subvariants BF.7 and BA.5.2 spreading in China are highly infectious and are more transmissible than the previously dominating Omicron subvariants. “The virus cannot be eliminated even under China’s strict control measures,” he wrote. “Its policy
‘SEXUAL ASSAULT’: Taipei prosecutors said that cooperation agreements between Taiwan and the Czech Republic grant Czech officials protection against prosecution The Taipei District Prosecutors’ Office yesterday reaffirmed that it would not charge a Czech official with sexual assault because he is protected by diplomatic immunity. The office released a statement saying it has verified that the man works for the Czech Economic and Cultural Office Taipei’s foreign affairs corps and is thereby protected from criminal prosecution. A foreign graduate student in Taiwan had filed a complaint alleging that the section head of the Czech Economic and Trade Section had sexually assaulted her on April 21 last year. The woman said the Czech official had invited her to his home and then forced her