Seoul has installed mechanical air filters in the heating, ventilation, and air conditioning (HVAC) systems of city buses to improve their indoor air quality since late 2019. We evaluated particle removal efficiencies of the filter in a wind tunnel, and clean air delivery rates (CADRs) of the systems and a household air purifier in the buses, following the test standards. The filter showed the efficiencies of 91% and 97.6%, 88% and 97.9%, and 78% and 95.2% for 0.35 μm particles and PM2.5 at 1.0m/s, 1.5m/s, and 2.0m/s, respectively. The efficiencies rose with an increase in the particle size and the filters had a minimum efficiency reporting value (MERV) rating of 15. The CADRs for PM2.5 and flow rate of the systems were 12.7m3/min and 17.9m3/min, 16.6m3/min and 25.4m3/min, 18.7m3/min and 33.6m3/min, and 23.3m3/min and 47.1m3/min on the operation mode of 1, 2, 3, and 4, respectively. The CADRs of the systems were 3.8-7.1 times higher than those of the air purifier, but single-pass removal efficiencies of the former were 0.56-0.81 lower than those of the latter.

Abstract
1. 서 론
2. 연구방법
    2.1 시내버스 공조기
    2.2 필터의 입자제거 성능평가
    2.3 버스 공조기의 청정화 성능평가
3. 결과 및 고찰
    3.1 필터의 입자제거 성능
    3.2 버스 공조기의 청정화 성능
4. 결 론
감사의 글
References

• 윤성진(서울기술연구원 기술개발본부 기후환경연구실) | Seongjin Yun (Department of Climate & Environmental Research, Seoul Institute of Technology (SIT)) Corresponding Author
• 최우석(세종대학교 데이터사이언스학과) | Woosuk Choi (Department of Data Science, Sejong University)
• 이주형(서울기술연구원 기술개발본부 기후환경연구실) | Joohyoung Lee (Department of Climate & Environmental Research, Seoul Institute of Technology (SIT))
• 이기용(서울기술연구원 기술개발본부 기후환경연구실) | Kiyong Lee (Department of Climate & Environmental Research, Seoul Institute of Technology (SIT))
• 전혜준(서울기술연구원 기술개발본부 기후환경연구실) | Haejoon Chun (Department of Climate & Environmental Research, Seoul Institute of Technology (SIT))