10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Indoor Fine and Ultrafine Aerosol Particles Exposure and Its Relationship to the Outdoor Concentrations in Private Homes
Jiangyue Zhao, Birgit Wehner, Thomas Tuch, Kay Weinhold, Maik Merkel, Ulrich Franck, Wolfram Birmili, Anja Lüdecke, Tareq Hussein, Lina Wang, ALFRED WIEDENSOHLER, TROPOS
Abstract Number: 321 Working Group: Indoor Aerosols
Abstract Nowadays people spend a large fraction of their lifetime indoor. Currently, only limited information is available about the exposure of residents to indoor fine and ultrafine particles, which can originate from either indoor or outdoor sources. It is thus important to study the contribution of outdoor sources and residential activities to the indoor air. The efficiency of penetration processes of aerosol particles from outdoor to indoor depends on the particle number size distribution (PNSD), meteorological conditions (e.g. wind speed, temperature), and residential building structure. Therefore, on behalf of the German Environment Agency (UBA), a project to study the indoor aerosol particle exposure and its relationship to the urban and rural atmosphere was granted to the Leibniz Institute for Tropospheric Research (TROPOS).
Measurements are performed in 40 households in two cites of Germany, households are located in the urban, suburban, and rural areas. Each household was or will be probed twice for one week, covering both, the cold and warm seasons. The first measurement period took place in Leipzig in 2017. Measured parameters for indoor and outdoor air have been the PNSD (0.01 – 0.8 µm), using mobility particle size spectrometers (MPSS, designed and build by TROPOS), and PM1, PM2.5, PM10 mass concentrations , using optical particle size spectrometers (Grimm Model 1.108). Additional indoor measurements were the equivalent black carbon mass concentration (microAeth Model AE51), and the indoor CO2 concentration (CO2 sensor, GMP252 Vaisala) to document the room ventilation. The measurements are accompanied by a questionnaire that documents the room characteristics and a digital notebook, capturing the residential activities. During the measurement, a new concept has been designed to determine indoor and outdoor PNSD of fine and ultrafine particles with high quality, as well as measurement of course mode particle mass concentrations. It is designed to perform measurement in multiple private homes over a period of more than one year, to obtain statistically more robust data.
This work presents results from the one-year measurement period in Leipzig, including the variation of particle number concentration (PNC) and I/O ratios in fine and ultrafine particle size ranges, caused by residential activities, as well as the evolution of different indoor particle sources. According to the variation of median of the indoor and outdoor PNCs, the outdoor PNC is generally higher than the indoor one. During nighttime (00:00 - 07:00), both indoor and outdoor PNCs decreased constantly due to less traffic and no indoor emissions. On the other hand, the indoor PNC and I/O ratio show peaks during breakfast, lunch and dinnertime. Ultrafine aerosol particles are especially produced due to cooking activities or candles burning. The 24-h median I/O is in the range of 0.4 to 1, its variation indicate that the indoor aerosol is increasingly decoupled from outdoor during nighttime and during daytime the influence of the outdoor aerosol is more significant (I/O ration close to 1). Black carbon concentrations will be compared to PNC of different size ranges to obtain a better understanding of the black carbon size range from different indoor sources.