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- Afshari, A, et al.
(author)
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Characterization of indoor sources of fine and ultrafine particles: a study conducted in a full scale chamber
- 2005
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In: Indoor Air. - : Hindawi Limited. - 1600-0668 .- 0905-6947. ; 15:2, s. 141-150
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Journal article (peer-reviewed)abstract
- Humans and their activities are known to generate considerable amounts of particulate matter indoors. Some of the activities are cooking, smoking and cleaning. In this study 13 different particle sources were for the first time examined in a 32 m3 full-scale chamber with an air change rate of 1.7 ± 0.1/h. Two different instruments, a condensation particle counter (CPC) and an optical particle counter (OPC) were used to quantitatively determine ultrafine and fine particle emissions, respectively. The CPC measures particles from 0.02 μm to larger than 1.0 μm. The OPC was adjusted to measure particle concentrations in eight fractions between 0.3 and 1.0 μm. The sources were cigarette side-stream smoke, pure wax candles, scented candles, a vacuum cleaner, an air-freshener spray, a flat iron (with and without steam) on a cotton sheet, electric radiators, an electric stove, a gas stove, and frying meat. The cigarette burning, frying meat, air freshener spray and gas stove showed a particle size distribution that changed over time towards larger particles. In most of the experiments the maximum concentration was reached within a few minutes. Typically, the increase of the particle concentration immediately after activation of the source was more rapid than the decay of the concentration observed after deactivation of the source. The highest observed concentration of ultrafine particles was approximately 241,000 particles/cm 3 and originated from the combustion of pure wax candles. The weakest generation of ultrafine particles (1.17 × 107 particles per second) was observed when ironing without steam on a cotton sheet, which resulted in a concentration of 550 particles/cm3 in the chamber air. The highest generation rate (1.47 × 1010 particles per second) was observed in the radiator test.
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- Matson, Uve, 1977, et al.
(author)
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Indoor and outdoor measurements of ultra fine particles in a medium-size and large city
- 2003
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In: Healthy Buildings 2003 - Proceedings 7th International Conference.
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Conference paper (peer-reviewed)abstract
- The concentrations of ultra fine particles (UFPs) were measured in the medium-size city ofGothenburg, Sweden, in the large city of Copenhagen and at a rural site in Denmark. InGothenburg, field measurements were conducted both in several residential and officebuildings, while in Denmark measurements comprise two office buildings, one of themlocated at a rural site. Concentrations of UFPs were measured simultaneously indoors andoutdoors. The results revealed that outdoor levels are major contributors to the indoor particlenumber concentration and the variability in concentrations is less pronounced indoors whenno indoor sources are present. The magnitude of UFP concentrations is higher in the large citycompared to the medium-size city. The results showed that in the Gothenburg office buildingsthe UFP concentrations indoors were fairly correlated to that outdoors. Another differencebetween Danish and Swedish offices is that in Denmark tobacco smoking is a main indoorsource of UFPs. The results from a Swedish residential building show that the indoorconcentration was strongly influenced by the indoor activity, e.g. cooking, ironing and byoutdoor levels mainly during window airing.
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- Matson, Uve, 1977
(author)
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Ultrafine Particles in Indoor Air. Measurements and modelling
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Clean air is one of the most fundamental human needs. Since people spen on average over 85% of their time indoors at work, home, school etc., human exposure to air pollution may mostly occur indoors. However, indoor exposure to airborne pollutants will not only depend on emissions from varoius indoor sources, but also on outdoor pollutants supplied through ventilation and infiltration. Assessing human exposure requires knowledge about the identity and the concentration of the pollutants. However, most available information is insufficient, especially concerning ultrafine particles (particles below 0,1µm in diameter). The purpose of this study is to determine the indoor number concentration of ultrafine particles (UFPs) in various non-industrial buildings, to clarify the contribution of outdoor UFPs to the indoor concentration, to identify important indoor sources, and to predict particle number concentrations indoors and the strength of sources and sinks by modelling. The sampling of UFPs has been performed in a laboratory and in various non-industrial buildings. The buildings concerned are located in Sweden and in Denmark. The measurements were made continuosly over hours with a 1-minute sampling interval using condensation particle counters. In the field studies, indoor and outdoor concentrations of UFPs were measured simultaneously. Indoor-outdoor (IO) concentration ratios were calculated for each building studied. In the laboratory different sources of UFPs were examined. An optical particle counter and an electrical low-pressure impactor were used to collect particle size distribution data for different particle fractions in the laboratory and outdoors, respectively. The studies revealed that outdoor UFPs are the major contributors to the indoor particle number concentrations, unless a strong indoor source was present, and that the concentration of UFPs may change rapidly. in office buildings the UFP concentrations were typically lower than outdoors leading to IO concentration ratios between about 0.5 and 0.8 (values averaged over working hours), which suggested rather strong indoor sink effects. Filtration of the supply air seemed to influence the indoor particle concentrations as the lowest indoor-outdoor ratios were observed in the building equipped with the highest class of supply air filter. In residential buildings, the indoor concentration was strongly influenced by several indoor human activities, e.g. cooking, candle-burning. The IO concentration ratios was from about 0.7 up to 2.5 in the presence of significant indoor sources. The laboratory sampling showed that frying, burning candles and cigarettes were stronger UFP sources than the other sources examined. Cigarettes, for example, produced a concentration of about 160 000 particles per cm3. The modelling approach successfully demonstrated its applicability for predicting the number concentration of UFPs indoors and for determining the strength of sources and sinks. Size distribution data revealed that particles below 0,1µm in diameter dominated the number concentration both inddors and outdoors. The study clearly indicates that a substantial fraction of the exposure to UFPs occurred indoors, and that the exposure indoors was different from that outdoors, not only regarding concentration levels, but also with respect to the compsition of the aerosol.
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| 12. |
- Matson, Uve, 1977
(author)
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Ultrafine Particles in the Indoor Environment: Field and Laboratory Measurements
- 2003
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Licentiate thesis (other academic/artistic)abstract
- Clean air is one of the most fundamental human needs since poor air quality affects the health and the environment. It has been shown that people spend on average over 85 % of their time at work, home, school etc. Therefore, human exposure to air pollution may occur mostly indoors. Despite this fact, outdoor air pollution is also important. Indoor exposure to airborne particles will not only depend on emissions from the various indoor sources, but also on the outdoor air which is linked to the indoor air through ventilation and infiltration. Assessing human exposure requires knowledge of the identity and the concentration of the pollutants. However, the available information is still limited, especially for particles smaller than 0.1 µm. The purpose of this study was to determine the indoor concentration of ultrafine particles (UFPs) in various non-industrial buildings, to identify the indoor sources and to clarify the contribution of outdoor UFPs to the indoor concentration. The measurements were conducted in a laboratory as well as in non-industrial buildings. The buildings concerned are located in Sweden and Denmark. The measurements were made continuously with a 1-minute sampling interval using two condensation particle counters. In the field studies, indoor and outdoor concentrations of UFPs were measured simultaneously. Indoor-outdoor concentration ratios were calculated for each building studied. In the laboratory different sources of UFPs were examined. An optical particle counter and an electrical low-pressure impactor were used to collect size distribution data for different particle fractions in the laboratory and outdoors, respectively. Size distribution data revealed that particles below 0.1 µm in diameter dominate the number concentration both indoors and outdoors. The concentration of UFPs may change rapidly, e.g outdoors by a factor of 2 within a few minutes. UFPs generated outdoors are supplied to buildings with the ventilation air and by infiltration. Often, such UFPs are the major contributors to the indoor particle levels unless a strong indoor source is present. Measurements in buildings without pronounced indoor UFP sources revealed rather strong indoor sink effects, leading to indoor-outdoor concentration ratios between about 0.5 and 0.75 (expressed as values averaged over the working hours). In buildings with indoor UFP sources the indoor-outdoor concentration ratio approached unity. Measurements conducted in a full-scale chamber indicated that burning candles and cigarettes, and frying are stronger UFP sources than the other sources examined. Cigarettes for example produced a concentration of about 160 000 particles cm-3. This value exceeds the highest outdoor concentration observed during the field measurements. The study clearly indicates that a substantial fraction of the exposure for UFPs can occur indoors, and that the exposure indoors is different from that outdoors, not only regarding concentration levels, but also with respect to the composition of the aerosol.
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