title: Ozone, Electrostatic Precipitators, and Particle Number Concentrations: Correlations Observed in a Real Office during Working Hours.
abstract: This study investigates the impacts of outdoor and indoor ozone concentrations, ESP operation and occupancy on particle number concentrations within a modern office in Changsha, China. The office's one-pass air handling system contains a mini-bag filter (MERV 12) followed by an electrostatic precipitator (ESP) and high efficiency particulate air (HEPA) filter. Over a five-week period the system was operated either without the ESP (Stage 1, first-third week) or with the ESP (Stage 2, fourth and fifth week). Ozone and particle number concentrations were measured on working days. During both stages, indoor ozone and particle number concentrations tracked the outdoor ozone concentration. When operating, the ESP produced approximately 29 mg h(-1) of ozone, increasing supply air ozone by 15 ppb and steady-state indoor ozone by about 3 ppb. Occupancy tended to decrease indoor ozone and increase particle levels. During occupancy, indoor particle levels were low (∼2600 particle/cm(3)) when the supply air ozone level was less than 18 ppb. Above this threshold, the supply air ozone concentration and indoor particle number concentration were linearly related, and ESP operation increased the average indoor particle level by about 22 000 particles/cm(3). The implications for worker exposure to both ozone and particles are discussed.
authors: Department of Building Science, Tsinghua University , Beijing 100084, China.|Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China.
authors: Jianbang
authors: J
authors: Xiang
authors: Department of Building Science, Tsinghua University , Beijing 100084, China.|Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China.|Environmental and Occupational Health Sciences Institute, Rutgers University , Piscataway, New Jersey 08854, United States.
authors: Charles J
authors: CJ
authors: Weschler
authors: Department of Building Science, Tsinghua University , Beijing 100084, China.|Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China.
authors: Jinhan
authors: J
authors: Mo
authors: Global Health Institute and the Nicholas School of Environment, Duke University , Durham, North Carolina 27708, United States.
authors: Drew
authors: D
authors: Day
authors: Global Health Institute and the Nicholas School of Environment, Duke University , Durham, North Carolina 27708, United States.|Duke Kunshan University , Kunshan, Jiangsu 215316, China.
authors: Junfeng
authors: J
authors: Zhang
authors: Department of Building Science, Tsinghua University , Beijing 100084, China.|Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Beijing 100084, China.
authors: Yinping
authors: Y
authors: Zhang
mesh_terms: D000393:Air Pollutants; D016902:Air Pollution, Indoor; D002681:China; D010126:Ozone; D010316:Particle Size; D055672:Static Electricity
chemical_list: D000393:Air Pollutants; D010126:Ozone