Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be ...affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six temperature levels between 20 and 30 C, i.e. within the normal fluctuation of indoor temperatures, while the air exchange rate was constant. The steady-state air concentrations of seven PCBs were determined at each temperature level. A model based on Clausius–Clapeyron equation, ln(P) = −ΔH/RT + a0, where changes in steady-state air concentrations in relation to temperature, was tested. The model was valid for PCB-28, PCB-52 and PCB-101; the four other congeners were sporadic or non-detected. For each congener, the model described a large proportion (R2>94%) of the variation in indoor air PCB levels. The results showed that one measured concentration of PCB at a known steady-state temperature can be used to predict the steady-state concentrations at other temperatures under circumstances where e.g. direct sunlight does not influence temperatures and the air exchange rate is constant. The model was also tested on field data from a PCB remediation case in an apartment in another contaminated building complex where PCB concentrations and temperature were measured simultaneously and regularly throughout one year. The model fitted relatively well with the regression of measured PCB air concentrations, ln(P) vs. 1/T, at varying temperature between 16.3 and 28.2 °C, even though the measurements were carried out under uncontrolled environmental condition.
•The effect of temperature on PCB air concentrations indoors.•Change in concentration due to temperature follows Clausius–Clapeyron equation.•Model predictions of concentrations match field intervention measurements, R2 > 0.94.•Additional field data substantiate the model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Airtight energy-efficient buildings of today need efficient ventilation to secure high indoor air quality. There is a need for affordable and reliable sensors to make demand control available in a ...broad range of ventilation systems. Low-cost metal oxide semiconductor (MOS) volatile organic compound (VOC) sensors offer such a possibility, but they are usually non-selective and react to broad range of compounds. The objective of the present paper was to use cluster analysis to assess the ability of five commercially available MOS VOC sensors to detect pollutants in a residential setting. We studied three scenarios: emissions from people (human bioeffluents), furnishing materials (linoleum), and human activity (surface cleaning with spray detergent). We monitored each scenario with five MOS VOC sensors and a proton-transfer-reaction–time-of-flight mass spectrometer (PTR-ToF-MS). We applied an agglomerative hierarchical clustering algorithm to evaluate the dissimilarity between clusters. Four of the five tested sensors produced signals in agreement with the concentration patterns measured with the PTR-ToF-MS; one sensor underperformed in all cases. Three sensors showed a very similar performance under all emission scenarios. The results showed that the clustering could help in understanding whether a particular sensor matched the intended emission scenario.
The impact of increased ventilation on polychlorinated biphenyl (PCB) air concentration by installation of mechanical balanced ventilation units was studied. The intervention was carried out in three ...PCB-contaminated rooms; one classroom in an elementary school and two small bedrooms in an apartment in a residential building. In the classroom, the air exchange rate (ACH) was raised from 0.2 (without mechanical ventilation) to 5.5 h−1 during the intervention. In the two bedrooms, the highest ACH was 6.6 h−1 and 0.5 h−1 without mechanical ventilation. The corresponding concentration decrease achieved from the intervention was 30% and in one of the bedrooms 45%. Emissions of PCB rose dramatically during periods of increased ventilation as the drop in concentration did not match the increased ACH. When ventilation in the bedrooms was increased incrementally from 0.5 to 2.2, 4.5, and 6.6 h−1, emissions were found to increase linearly with increasing ACH. Compared with the sparse literature regarding estimated reductions due to ventilation, the measured effect on concentrations was less than expected.
•Investigation of the effect of ventilation on PCB indoor air concentration.•Highest reduction of indoor air concentration of PCBs ranged between 30 and 46%.•A constant emission rate model overestimates the reduction in concentration.•PCB emission rate is directly proportional to air exchange rate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Polychlorinated biphenyls (PCBs) were used in building materials like caulks and paints from 1930–1970s and in some cases that caused elevated PCB concentrations in the indoor air at levels ...considered harmful to occupant health. PCBs are semivolatile organic compounds and capable of spreading from the original source to adjacent materials, indoor air and via adsorption from the air to indoor surfaces, causing secondary contaminations. Remediation of buildings with unsatisfactory indoor air concentrations is a complex and difficult task due to the secondary contamination of building materials and there is a need to prioritise remediation measures on different materials. An inexpensive and portable emission test cell was developed to resemble indoor conditions in relation to the area specific ventilation rate. Emissions were measured using the test cell in the laboratory on freshly made PCB paint. Further, the chamber was used for determining emissions from PCB-containing building materials in the field as well as remediated walls. The measurements showed that sorption of PCBs to chamber walls was insignificant after 2–4 days of exposure to the source. Over a period of two weeks emission rates did not change from any of the tested surfaces, however in the laboratory experiment emission rates decreased over a longer period (48 days) and was most pronounced for the lower chlorinated PCBs.
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•Development of a low-cost emission test cell for measuring emissions of PCBs indoors.•The emission test cell can be used for in-situ non-destructive measurements.•The emission test cell can be used to prioritise and evaluate remediation measures.•Measurements of PCB emissions from freshly made paint containing PCB.•Field measurements of PCB emissions from surfaces such as floors and painted walls.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
