basement station indoor air quality measurement

• based reason : law No.12 of indoor air quality management(indoor air quality measurement)
• maintenance standard and the measured results(how often to measure: annually)

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  maintenance standard and the measured results

  (based on year 2025)
  division	fine dust (㎍/㎥)	ultrafine dust (㎍/㎥)	carbon dioxide (ppm)	form aldehyde (㎍/㎥)	carbon monoxide(ppm)
  standard	less than 100㎍/㎥	less than 50㎍/㎥	less than 1,000ppm	less than 100㎍/㎥	less than 10ppm
  average	29.7	16.8	422	4.9	0.6
  line1	32.0	18.8	420	4.1	0.6
  line2	31.2	15.6	407	6.7	0.6
  line3	28.6	17.2	442	4.4	0.6
  line4	27.0	15.7	421	4.5	0.6

• recommended standard & measured result(how often to measure: once every two years)

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  recommended standard & measured result

  (based on year 2025)
  division	nitrogen dioxide (ppm)	radon (Bq/m3)	volatile organic compounds (㎍/㎥)
  standard	less than 0.1	less than 148	less than 500
  average	0.021	21.3	110.6
  line 1	0.022	16.1	92.3
  line 2	0.021	15.3	112.5
  line 3	0.020	26.7	123.4
  line 4	0.024	27.1	114.4

Air quality measurement in the motor car

• based reason : Law No.9 article 2 of indoor air quality management(Measurement on Indoor Air Quality in Public Transportation Vehicles)
• measured result

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  measured result

  (based on year 2025)
  division	ultrafine dust (PM2.5)	carbon dioxide (CO2)
  standard	less than 50㎍/㎥	less than 2,000ppm(uncrowded)	less than 2,500ppm(crowded)
  average	8.4	1,182	1,262
  line1	9.4	1,205	1,202
  line2	8.1	1,139	1,197
  line3	11.0	1,268	1,503
  line4	5.1	1,117	1,147

efforts to improve air quality

ventilation facility operation for the clean environment

air screening device periodic filter cleaning

• As air filter device is installed in the air inlet and the air conditioner, outdoor air can go through the filter and fresh air come in the station
• period : auto cleaning(once a day), manual cleaning(once a month), high pressure cleaning (annually)

water washing in the ground tunnel

• periodic cleaning is a must for clean and fresh environment

enhancement and exchange of old ventilation facility

• ventilation fan exchange, station ventilation duct enhancement, air filtering device exchange