Online & Oslo, Norway
21-23 June 2021
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Session 5: Indoor particles, aerosols and VOCs
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10:30am - 10:35am
Indoor Aerosols - Calculation of Zonal Particle Concentration and Particle Deposition in the Human Respiratory Tract
TH Köln (University of Applied Sciences), Institute of Building Services Engineering, 50679 Cologne, Germany
This study presents a modeling approach to calculate the particle concentration in mechanically conditioned indoor environments and predict particle deposition in the Human Respiratory Tract (HRT) by combining two aerosol models. The developed Indoor Aerosol Model (IAM) combines the semi-empirical Respiratory Deposition Model (RDM) presented by the International Commission on Radiological Protection (ICRP) in its publication 66/130 with a Material Balance Model (MBM). This enables the determination of total regional deposition fractions in the HRT for different particle diameters, subjects, levels of exertion or respiration types. These total regional deposition fractions are then incorporated into the MBM, which can be used to determine the number and mass of particles deposited in the HRT over a maximum period of 24 hours. Furthermore, the time history of the airborne particle concentration, as well as the surface loading and, in addition, the particle fate can be determined for well-mixed single zones.
10:35am - 10:40am
Effects of suspended particles, chemicals, and airborne microorganisms in indoor air on building-related symptoms: a longitudinal study in air-conditioned office buildings
1Kindai University Faculty of Medicine, Japan; 2Tokyo Institute of Technology, Japan; 3Kogakuin University, Japan; 4National Institute of Public Health, Japan; 5Hokkaido University, Japan
We conducted a one-year longitudinal study in Osaka and Tokyo to examine the effects of suspended particles, chemicals, and airborne microorganisms in indoor air on building-related symptoms (BRSs) in air-conditioned office buildings. In total, 648 subjects, in 24 office rooms and eleven office buildings, were recruited for the present study. In order to collect information on BRSs and those indoor air pollutants in the office room, we measured air concentrations of carbon monoxide (CO), suspended particles [particle counts of each cutoff size in diameter (>0.3 μm, >0.5 μm, >0.7 μm, >1.0 μm, >2.0 μm, >5.0 μm)], PM2.5, formaldehyde, acetaldehyde, volatile organic compounds (benzene, toluene, ethylbenzene, xylenes, styrene, p-dichlorobenzene, and tetradecane), total volatile organic compound (TVOC), fungi, bacteria, and endotoxin in the office rooms and provided a health questionnaire once every two months for one year. The sampling interval for these compounds was 30 min in a single day. The surveys were conducted between June 2015 and February 2017. In total, 483 office workers (53.4% male, 46.6% female) participated in the present study. Of the 4520 questionnaires distributed during the survey, 1800 valid responses were obtained (response rate, 39.8%). Weekly BRS was defined as symptoms experienced at least 1 day per week in the last 4 weeks that improved when one was away from the building, suggesting the associations between health symptoms and work environment are strong. Monthly BRS showed symptoms that were experienced at least 1 day in the last 4 weeks that improved when one was away from the building, suggesting the associations between health symptoms and work environment are weak. Multivariable analyses revealed that weekly BRSs, including eye irritation, upper respiratory symptoms, and general symptoms were not significantly correlated with indoor air pollutants. In monthly BRSs, upper respiratory symptoms were significantly correlated with increase of air concentrations of benzene, ethylbenzene, and Acremonium species. On the other hand, upper respiratory symptoms were significantly correlated with decrease of air concentrations of CO, endotoxin, and yeast species. Indoor air concentrations of benzene and ethylbenzene were lower than those specified in Japanese air quality guidelines. Although the indoor air concentration of each pollutant was low, when they collectively exist in an indoor environment, they can lead to a greater combined health risk. Our data suggests that further research on the total health risk due to multiple low-level indoor pollutants is required.
10:40am - 10:52am
Human personal cloud associated with particles and gases in an office study: Preliminary results
École polytechnique fédérale de Lausanne (EPFL), Switzerland
“Personal cloud” is defined as the concentration difference of air pollutants in breathing zone relative to room-average levels. The personal cloud of air pollutants is commonly encountered in indoor environments where the air is not well-mixed. Yet, investigations on the nature and significance of the human personal clouds remain scarce. This study aims to quantify the magnitude of personal air pollutant cloud in an office environment and to probe the relative importance of several personal and environmental factors.
In a three-person naturally ventilated office, we measured the personal clouds of CO2, volatile organic compounds (VOCs), ozone, total particles (10 nm - 10 μm), fluorescent biological aerosol particles (FBAPs) and airborne microbes. The field experiment ran continuously for two weeks: 1) “standard office work without manipulation” and 2) “manipulation week”. The first-week measurement aimed to investigate daily nature of personal cloud and the potential disparities among occupants. We measured 0.3-10 μm particles, VOCs, CO2 and airborne microbes at the breathing ozone of the three occupants, as well as at four stationary locations in the office so as to quantify the personal clouds. Additional measurements were taken in the breathing zone of Occupant #1 and at one stationary site, where we monitored concentration differences of FBAPs, ultrafine particles (10-100 nm) and ozone. The objective of the second (“manipulation”) week was to examine the influence of application of personal care product and hand sanitizer, cooking activities during the lunch break, clothing worn over extended period, office occupancy density and distance from other occupants. Here, personal cloud was characterized for the Occupant #1 only. During the experimental period, outdoor concentrations of the target air pollutants were also recorded. Additionally, occupants’ activities were recorded using daily questionnaire and on-site occupancy sensors.
The preliminary results have shown that the VOC personal cloud magnitude can range within 100-1000 μg/m3, depending on specific compounds and occupants. The ongoing data analyses are expected to reveal the magnitude of human personal clouds of diverse air pollutants in the office environment, and to quantify the relative importance of factors contributing to the personal clouds. The results are valuable for refined characterization and enhanced control of personal exposure to air pollutants.
10:52am - 11:04am
Experimental & Modelling Studies for the Determination of Pollutant Emissions from Cooking and Cleaning
1University of York, United Kingdom; 2University of Chester, United Kingdom; 3University of Nottingham, United Kingdom
In developed countries, we spend approximately 90% of our time indoors, and a significant fraction of this time within our homes. Consequently, exposure to air pollutants typically happens almost exclusively indoors, even for pollutants generated outdoors, which ingress via windows, doors and cracks in buildings. Occupant activities such as cooking and cleaning produce high pollutant concentrations, with concomitant impacts on human health including respiratory and cardiovascular diseases.
The IMPeCCABLE project aims to enhance our knowledge of the impact of cooking and cleaning on indoor air quality through a combination of experimental and modelling studies. Research into pollutant emissions from cooking and cleaning activities indoors, and the subsequent chemistry that occurs following these emissions, will enable the identification of strategies to remediate against high indoor air pollutant concentrations, leading to improved building design and management and enhanced indoor air quality.
Although measurements of cooking and cleaning emissions exist, they tend to focus on a few emission rates, rather than studying a wide range of emitted species and the chemistry that follows from the emissions. The IMPeCCABLE project adopts a holistic approach with combined experiments and modelling studies over a range of spatial scales, to understand the resulting IAQ when we cook and clean indoors at the process level.
We will present findings from multiple experiments, focussed on measuring emission profiles during cooking and cleaning activities of varying complexity. Online measurements of volatile organic compounds (VOCs) and particulate matter (PM) were obtained using selected ion flow tube mass spectrometry (SIFT-MS) and optical particle counter (OPC), respectively, during cooking and cleaning activities performed within kitchen spaces. These measurements were supplemented by offline gas chromatography mass spectrometry (GC-MS) of air samples, as well cleaning product formulation headspace. Cooking experiments included the frying and toasting of spices, frying meat, toasting bread and cooking full meals. Cleaning experiments were focussed on measuring emissions from the use of a range of cleaning products, including those which are marketed as green products.
The pollutant emission profiles obtained from these experiments will feed in to the INCHEM-Py model, which will permit greater insight into the chemistry occurring, particularly around radical chemistry and secondary pollutant formation and estimated human exposures. Further experiments at a test house facility will enable more controlled cooking and cleaning experiments, which will aid development of the model.
11:04am - 11:09am
Characterization of PM2.5 and its Indoor-Outdoor Ratio in an Office Building Connected to a Chemical Production Plant in Gebeng Industrial Zone, Pahang Malaysia
1Faculty of Industrial Science and Technology, Universiti Malaysia Pahang, Malaysia; 2Kuliyyah of Science, International Islamic University Malaysia, Malaysia
PM2.5 is a dominant pollutant in indoor air, also a carrier for many toxic compounds. This study aims to characterize PM2.5 in terms of mass concentration, polycyclic aromatic hydrocarbons (PAHs) and elementals concentrations bound to PM2.5, and to determine indoor and outdoor (I/O) ratio of PM2.5 in the office which is connected to the chemical production plant. The samples were taken for every 8 hours during working days at five sampling points such as outdoor environment (one location), the production plant (one location), and indoor office (three location) via a hand-held dust detector instrument. The filters attached to the instrument were then analysed by using Inductively Coupled Plasma-Mass Spectrometry and Gas Chromatography- Flame Ionization Detector to determine the elementals and PAHs bound to PM2.5, respectively. The results indicated that the mass concentrations of PM2.5 (4.72±1.89 µg/m3 - 55.1±12.29 µg/m3) and PAHs (acenapthylene (0.0001-0.0002ppm), phenanthrene (0.0001 - 0.0002ppm), fluoranthene (0.0001ppm), pyrene (0.0001ppm), benz(a)anthrancene (0.0002 - 0.0004ppm), chrysene (0.0001 - 0.0002ppm), benzo(a)fluoranthene (0.0001 - 0.0002ppm) and benzo(a)pyrene (0.0001 - 0.0002ppm)) were below the recommended values of World Health Organisation. The elementals such as Ba (0.804±0.302 ppm – 3.246±0.092 ppm), Al (0.121±0.002 ppm – 3.45±1.02 ppm), Ga (0.029±0.001 ppm – 0.112±0.023 ppm), Se (0.002±0.001 ppm – 0.003±0.017 ppm), Co (0.002±0.001 ppm – 0.0095±0.002 ppm were complied with the permissible exposure limit (PEL) of The Occupational Safety and Health (Use and Standards of Exposure of Chemicals Hazardous to Health) Regulations 2000 (USECHH Regulations 2000). However, Si (5.362±2.012 ppm – 25.1±5.012 ppm) was found to be the most abundant element and noncompliant with the PEL. The I/O relationship revealed that the source of PM2.5 and elementals are mainly contributed by the outdoor sources. In contrast, the source of PAHs is solely modulated by sources within the building. In conclusion, high concentration of Si found in the office indicated serious indoor air pollution and may contribute to the potential health risks for the workers.
11:09am - 11:21am
Phytoremediation of Airborne Particulate Matter in Indoor Environments
Birla Institute of Technology and Science, Pilani, India
This research is motivated by the urgent need to protect people from the adverse health effects of PM2.5 (particles smaller than 2.5 μm in size) exposure by using potted plants as air filters in indoor environments. We quantified the ability of three different plant species for removing airborne particles by conducting experiments in an environment-controlled chamber. The plants selected were Christmas plant (Araucaria heterophylla, a needle-leaved plant), Ficus plant (Ficus retusa, a small-leaved plant), and Croton plant (Codiaeum variegatum, a broad-leaved plant). The particle deposition velocities ranged from (32.4±10.6 to 41.0±10.8) cm/h for the Christmas plant, (0.6±1.6 to 2.53±3.27) cm/h for the Ficus plant, and (−0.09±3.8 to 6.07±6.28) cm/h for the Croton plant, depending on the particle size. On extrapolating those results to a small residential room, we found that 35–44 Christmas plants (the most effective species) would be required for reducing the steady-state PM2.5 concentration by 10% at an air exchange rate of 0.5 h−1.
11:21am - 11:26am
How Does Indoor Air Chemistry Affect Outdoor Air Pollution?
University of York, United Kingdom
Most air pollutant exposure happens indoors, particularly in our homes. Activities such as cooking and cleaning can be a large source of indoor air pollutants, with some emitted species further reacting to form secondary pollutants. Some indoor air pollutants are potentially harmful to health. Recent evidence also suggests that air pollutants released indoors can significantly impact outdoor air quality. This paper uses a detailed indoor air chemistry model to estimate the impact of indoor activities such as cooking and cleaning on outdoor air quality. We show that cooking and cleaning can enhance indoor air pollutant concentrations by a factor of 200 and provide a source of air pollutants to outdoors of a few ppb per hour. Our results suggest that as outdoor air quality improves such as through electrification of the vehicle fleet, such indoor activities will need to be considered for their impacts on outdoor as well as indoor air quality.
11:26am - 11:31am
Green Plant Walls as an Indoor Air Quality Enhancer in a Recently Built Office Building
1Riga Stradins University, Latvia; 2Ko Tu Elpo Ltd, Latvia
Objectives. Nowadays one of the main focus of public and occupation health is maintain good indoor air quality in office building and public spaces. The aim of this study was to identify indoor air quality, its influencing factors, sources of pollution and air quality enhancers.
Materials and Methods. The data were obtained from recently built and furnished office. The office building was chosen because of worker complains about poor air quality. The quantitative measurements were performed on 2 floors – the control floor (without green plant walls) and test floor. Measured air parameters was temperature, humidity, CO2 levels, chemical pollutants, the number of dust particles, also office workers filled out health and air quality questioners. The data were collected in in two measurement phases, before and after living green wall adaptation period. Data was analysed using IBM SPSS Statistic 26.0.
Results. The results indicate that indoor air quality does not exceed the permissible levels for office buildings based on found chemical pollutants and CO2 readings. Identified sources of chemical pollutants were: printers with tonner, personal cosmetic products of workers, hand disinfectant and office cleaning products. Measurements indicated well ventilated rooms. However, the control floor showed lower air humidity levels. Results shows up to 22% air humidity boost from plant green walls on weekends and up to 20% boost on work days.
Conclusion. The green walls with living plants help maintain good humidity levels, but not enough due to high air flow from ventilation systems. To optimize the air quality in offices’, it is recommended to make adjustments for the ventilation system to maintain 800 ppm CO2 instead of 500 – 600 ppm, or instal recuperation system with moisturising module. This ensures both a good CO2 and higher humidity concentration, as the humidity would not be removed so intensively. Emissions are effectively removed from the potential emission sources of chemical pollution, thus reducing ventilation system capacity would not increase chemical pollution, as it is significantly below the recommended values by WHO issued standards. The low levels of VOC’, aldehydes and CO2 concentrations show good ventilation system’s efficiency, but lack of air humidity regulation without build-in humidifier system of green plant walls installation in the office premises.
Acknowlegments: This study was supported by Rigas Stradiņš University Vertical integrated projects (VIP) and KoTuElpo Ltd (plant green walls producer).
11:31am - 11:36am
Characterising multi-sensor platforms performance to investigate indoor air quality events, and quantify personal exposure
IMT Lille Douai, Institut Mines-Telecom, Univ. Lille, Center for Energy and Environment
In the area of Indoor Air Quality assessment and personal exposure, the use of gas and particulate multi-sensor systems has become commonplace. Nevertheless, most of the studies focus on particles and CO2 sensor measurements. Regarding Volatile Organic Compounds, experiments are often limited to a rough evaluation of total VOCs, without even ensuring the ability of the sensors used to exhaustively quantify this parameter. Given their strong impact on health it is however essential to have tools capable to distinguish the diversity of VOCS sources in indoor air. In this study, the metrological performances of 40 replicas of 2 types of VOC sensors: 4 MOX (Figaro, Cambridge CMOS Sensors, SGX Sensortech) and 1 electrochemical (sense), are evaluated under controlled conditions. They are exposed to 5 VOCs representative of indoor environments (formaldehyde, acetaldehyde, acetone, ethanol, limonene and their mixture) in a 1:1 scale experimental room based on their prevalence and their hazardousness summarized in guidelines. The correlation curves are established by comparison with the responses of a Selected-Ion Flow-Tube mass spectrometer (SIFT-MS). The results show that the electrochemical sensor, supposed to be dedicated to total VOCs, is acetone-blind and underestimates by a factor of 3 the real quantity of VOCs present, while MOX 1/ require pre-processing of the data to estimate reproducibility, 2/ have differentiated sensitivities by type of VOC, but without homogeneity by family of VOCs, 3/ have non-linear responses depending on the concentration ranges, 4/ can be combined with advanced statistic tools to establish a specific pollutant footprint of the VOCs considered. These results will help to interpret the data from the Qalipso campaign, during which these sensors were deployed for 4 months in 40 households in Douai city in Northern France. The purpose of the Qalipso project is to evaluate changes in citizens' behavior towards their exposure to indoor air pollution.
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