Indoor and outdoor BTX levels in German cities

On the basis of the ongoing study INGA (INdoor exposure and Genetics in Asthma), Germany's most detailed and standardized epidemiological study on indoor exposure to both allergens in house dust and volatile compounds in the air of the home environment has been performed. The purpose of this paper is to describe the spatial and seasonal variability of indoor and outdoor BTX (Benzene, toluene, ethyl benzene, ortho-xylene, meta- and para-xylene) concentrations for the study period from June 1995 to November 1996. Within this framework, air concentrations of volatile organic compounds (BTX) were measured in 204 households in Erfurt (Eastern Germany) and 201 households in Hamburg (Western Germany). BTX sampling was conducted over one week using OVM 3500 passive diffusion sampling devices in the indoor (living room and bedroom) and outdoor environment (outside the window of the living room). Indoor and outdoor median BTX concentrations in Erfurt were slightly, but significantly higher than those in Hamburg. This gap was most pronounced in the levels of indoor toluene (37.3 microg/m3 for Erfurt and 20.5 microg/m3 for Hamburg, P < 0.0001). In both cities, winter indoor and outdoor concentrations for the five compounds exceeded the summer values. Outdoor concentrations of ethyl benzene and ortho-xylene were very low (50% < L.D.). In general, the indoor BTX air concentrations were significantly higher than the outdoor concentra- tions, the lowest I/O ratios were found in the case of benzene. Living room and bedroom values for the five compounds were highly correlated (Spearman coefficient 0.5-0.9). Despite the better insulation of the homes in West Germany, no indication for the expected higher indoor concentrations of BTX in the West could be found. The strong and yet undiscovered indoor source for toluene in East Germany might lead to a further increase in the indoor air load in those homes in the East, which undergo renovations which will lead to improved insulation.     

Effects of climate change on the wash-off of volatile organic compounds from urban roads

The predicted changes in rainfall characteristics due to climate change could adversely affect stormwater quality in highly urbanised coastal areas throughout the world. This in turn will exert a significant influence on the discharge of pollutants to estuarine and marine waters. Hence, an in-depth analysis of the effects of such changes on the wash-off of volatile organic compounds (VOCs) from urban roads in the Gold Coast region in Australia was undertaken. The rainfall characteristics were simulated using a rainfall simulator. Principal Component Analysis (PCA) and Multicriteria Decision tools such as PROMETHEE and GAIA were employed to understand the VOC wash-off under climate change. It was found that low, low to moderate and high rain events due to climate change will affect the wash-off of toluene, ethylbenzene, meta-xylene, para-xylene and ortho-xylene from urban roads in Gold Coast. Total organic carbon (TOC) was identified as predominant carrier of toluene, meta-xylene and para-xylene in < 1 μm to 150 μm fractions and for ethylbenzene in 150 μm to > 300 μm fractions under such dominant rain events due to climate change. However, ortho-xylene did not show such affinity towards either TOC or TSS (total suspended solids) under the simulated climatic conditions.     

Mass concentrations of BTEX inside air environment of buses in Changsha,China

In order to estimate the mass concentrations of benzene (B), toluene (T), ethylbenzene (E) and xylenes (X) inside air environment of buses and to analyze the influencing factors of the BTEX pollution levels, 22 public buses were investigated in Changsha, China. The interior air was collected through activated charcoal adsorption tubes and then the air samples were analyzed with thermally desorbed gas chromatograph. The mass concentrations ranged from 21.3 to 106.4 μg/m³ for benzene, from 53.5 to 266.0 μg/m³ for toluene, from 19.6 to 95.9 μg/m³ for ethylbenzene and from 46.9 to 234.8 μg/m³ for xylenes. Their mean values were 68.7, 179.7, 62.5 and 151.8 μg/m³, respectively. The rates of buses tested where the interior concentrations exceeded the limit levels of Chinese Indoor Air Quality Standard were 45.5% for toluene and 13.6% for xylenes. The BTEX levels increased when in-car temperature or relative humidity rose, and decreased when car age or travel distance increased. The BTEX concentrations were higher in leather trims buses than in non-leather trims ones, in air-conditioned buses than in non-air-conditioned ones, and in high-grade buses than in low-grade ones. According to the analysis of multiple linear regression equation, car age and in-car temperature were two most important factors influencing the BTEX pollution levels in the cabins of public buses.     

Characterization of indoor air quality in primary schools in Antwerp, Belgium

The indoor air quality of 27 primary schools located in the city centre and suburbs of Antwerp, Belgium, was assessed. The primary aim was to obtain correlations between the various pollutant levels. Indoor:outdoor ratios and the building and classroom characteristics of each school were investigated. This paper presents results on indoor and local outdoor PM2.5 mass concentrations, its elemental composition in terms of K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Pb, Al, Si, S, and Cl, and its black smoke content. In addition, indoor and local outdoor levels of the gases NO2, SO2, O3, and BTEX (benzene, toluene, ethyl benzene, and xylene isomers) were determined. Black smoke, NO2, SO2 and O3, occurred at indoor:outdoor ratios below unity, indicating their significant outdoor sources. No linear correlation was established between indoor and outdoor levels for PM2.5 mass concentrations and BTEX; their indoor:outdoor ratios exceeded unity except for benzene. Classroom PM2.5 occurred with a different elemental composition than local outdoor PM2.5. The re-suspension of dust because of room occupation is probably the main contributor for the I/O ratios higher than 1 reported for elements typically constituting dust particles. Finally, increased benzene concentrations were reported for classrooms located at the lower levels. PRACTICAL IMPLICATIONS: The elevated indoor PM2.5, and BTEX concentrations in primary school classrooms, exceeding the ambient concentrations, raise concerns about possible adverse health effects on susceptible children. This is aggravated by the presence of carpets and in the case of classrooms at lower levels. Analysis of PM2.5's elemental composition indicated a considerable contribution of soil dust to indoor PM2.5 mass. In order to set adequate threshold values and guidelines, detailed information on the health impact of specific PM2.5 composites is needed. The results suggest that local outdoor air concentrations measurements do not provide an accurate estimation of children's personal exposures to the identified air pollutants inside classrooms.     

Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling

Benzene, toluene, m/p-xylene and o-xylene (BTX) are toxic volatile organic compounds and ubiquitous air pollutants. Smoking and consumer products are indoor sources of BTX, whereas traffic and industrial activities are primary sources contributing to outdoor levels of BTX. The aim of this study was to characterize exposure of children to BTX by personal air sampling using diffusive samplers and by analysis of end-exhaled air. For this study, 101 children of 10-11 years of age were recruited from four primary schools in Southern Turkey during the warm season (May 2008). Two schools were situated in a residential area near primary and secondary iron and steel works (Payas) and two schools were located in a non-industrialized city (Iskenderun). The children and their parents were visited at home for an interview and to identify possible sources of BTX in the residence. Median concentrations of benzene determined by diffusive samplers were higher in Payas (4.1 μg/m³) than in Iskenderun (2.7 μg/m³, p < 0.001). For toluene, no differences were observed, whereas for xylene isomers air concentrations tended to be lower for children living in Payas. The median end-exhaled air concentrations were 8.2, 29, 3.8, and 5.7 pmol/L for benzene, toluene, m/p-xylene and o-xylene, respectively (Payas), and 6.9, 25, 4.9, and 6.0 pmol/L, respectively (Iskenderun). Concentrations of toluene in end-exhaled air were 50% higher in children living with household members who smoked indoors (p < 0.05) and benzene in end-exhaled air was more than 3-fold higher for those children who were exposed to tobacco smoke inside a vehicle (p < 0.001). End-exhaled concentrations of benzene were also higher in children living in a residence with an attached garage (p < 0.05). These exposure modifying factors were not identified when using the results obtained with diffusive samplers.     

Atmospheric levels of BTEX compounds during the 2008 Olympic Games in the urban area of Beijing

The hourly concentrations of BTEX (Benzene, Toluene, Ethylbenzene, m,p-Xylene and o-Xylene) in the urban area of Beijing were measured during July-October 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. The atmospheric BTEX were pre-concentrated on Tenax-TA tubes, and analyzed by GC-PID (Gas Chromatography with Photo Ionization Detector) after thermal desorption. During the games, the mean daytime concentrations of benzene, toluene, ethylbenzene, m,p-xylene and o-xylene were 2.37, 3.97, 1.92, 3.51 and 1.90 μg/m³, respectively, and were 52.8%, 63.9%, 56.4%, 56.8% and 46.9%, respectively lower than those after the games. The significantly positive correlation between BTEX and CO as well as the ratio of benzene/toluene suggested that the vehicle exhaust was the major source of BTEX during the whole investigated period. The extremely high ratios of ethylbenzene to m,p-xylene (E/X) were mainly observed at noontime in haze days, indicating that photochemical reactions were highly active under these typical days.     

Urinary BTEX, MTBE and naphthalene as biomarkers to gain environmental exposure profiles of the general population

The aim of this work was to evaluate urinary benzene, toluene, ethylbenzene, m+p-xylene, o-xylene (BTEX), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and naphthalene (NAP) as biomarkers of exposure to environmental pollutants. Personal air and urine samples from 108 subjects belonging to the Italian general population were compared. Urinary profiles were obtained by headspace gas chromatography-mass spectrometry. BTEX, MTBE, ETBE and NAP median airborne exposures during a 5-h sampling were 4.0, 25.3, 3.8, 9.3, 3.4, 3.4, < 0.8, and 3.4 µg/m³, respectively. Meanwhile, median urinary levels, as geometric means of three determinations were: 122, 397, 74, 127, 43, 49, < 15, and 46 ng/L, respectively. Urinary benzene and toluene concentrations were 4.6- and 1.2-fold higher in smokers than in non-smokers. For most chemicals, significant positive correlations between airborne exposure (log-transformed) and the corresponding biological marker (log-transformed) were found, with Pearson's r values for correlation, ranging from 0.228 to 0.396. Multiple linear regression analysis showed that the urinary level of these chemicals was influenced by personal airborne exposure, urinary creatinine, and urinary cotinine, with R² 0.733 for benzene. Urinary chemicals are useful biomarkers of environmental exposure. Given the ease of rapidly obtaining urine samples, they represent a non-invasive alternative to blood chemical analysis. The possibility of obtaining urinary exposure profiles makes this method an appealing tool for environmental epidemiology.     

Effect of ethanol on BTEX biodegradation kinetics: aerobic continuous culture experiments

The use of ethanol as an automotive fuel oxygenate represents potential economic and air-quality benefits. However, little is known about how ethanol may affect the natural attenuation of petroleum product releases. Chemostat experiments were conducted with four pure cultures (representing archetypes of the known aerobic toluene degradation pathways) to determine how ethanol affects benzene, toluene, ethylbenzene, and xylene (BTEX) biodegradation kinetics. In all cases, the presence of ethanol decreased the metabolic flux of toluene (measured as the rate of toluene degradation per cell). This negative effect was counteracted by an ethanol-supported increase in biomass, which is conducive to faster degradation rates. When the influent total organic carbon (TOC) of the toluene-ethanol mixture was kept constant, the metabolic flux of toluene was proportional to its relative contribution to the influent TOC. This empirical relationship was used to derive a mathematical model that simulated effluent benzene concentrations as a function of the influent mixed-substrate composition, the dilution rate, and Monod kinetic coefficients. Under carbon-limiting conditions (1 mg/L influent benzene), the data and model simulations showed an increase in benzene removal efficiency when ethanol was fed at low concentrations (ca. 1 mg/L) because its positive effect on cell growth outweighed its negative effect on the metabolic flux of benzene. High ethanol concentrations, however, had a negative effect, causing oxygen limitation and increasing effluent benzene concentrations to higher levels than when benzene was fed alone. The slower BTEX degradation rates expected at sites with high ethanol concentrations (e.g., at gasohol-contaminated sites) could result in longer BTEX plumes and a greater risk of exposure.     

Enumeration of aromatic oxygenase genes to evaluate monitored natural attenuation at gasoline-contaminated sites

Monitoring groundwater benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations is the typical method to assess monitored natural attenuation (MNA) and bioremediation as corrective actions at gasoline-contaminated sites. Conclusive demonstration of bioremediation, however, relies on converging lines of chemical and biological evidence to support a decision. In this study, real-time PCR quantification of aromatic oxygenase genes was used to evaluate the feasibility of MNA at two gasoline-impacted sites. Phenol hydroxylase (PHE), ring-hydroxylating toluene monooxygenase (RMO), naphthalene dioxygenase (NAH), toluene monooxygenase (TOL), toluene dioxygenase (TOD), and biphenyl dioxygenase (BPH4) genes were routinely detected in BTEX-impacted wells. Aromatic oxygenase genes were not detected in sentinel wells outside the plume indicating that elevated levels of oxygenase genes corresponded to petroleum hydrocarbon contamination. Total aromatic oxygenase gene copy numbers detected in impacted wells were on the order of 10(6)-10(9)copies L(-1). PHE, RMO, NAH, TOD, and BPH4 gene copies positively correlated to total BTEX concentration. Mann-Kendall analysis of benzene concentrations was used to evaluate the status of the dissolved BTEX plume. The combination of trend analysis of contaminant concentrations with quantification of aromatic oxygenase genes was used to assess the feasibility of MNA as corrective measures at both sites.     

Differences in cyclists and car drivers exposure to air pollution from traffic in the city of Copenhagen.

It has frequently been claimed that cycling in heavy traffic is unhealthy, more so than driving a car. To test this hypothesis, teams of two cyclists and two car drivers in two cars were equipped with personal air samplers while driving for 4 h on 2 different days in the morning traffic of Copenhagen. The air sample charcoal tubes were analysed for their benzene, toluene, ethylbenzene and xylene (BTEX) content and the air filters for particles (total dust). The concentrations of particles and BTEX in the cabin of the cars were 2-4 times greater than in the cyclists' breathing zone, the greatest difference being for BTEX. Therefore, even after taking the increased respiration rate of cyclists into consideration, car drivers seem to be more exposed to airborne pollution than cyclists.     

Investigation of BTEX removal efficiency using the electrolytic oxidation and Fenton’s reaction

The removal of benzene, toluene, ethyl benzene, and xylene (BTEX) using the electrolytic oxidation or Fenton’s reaction has been studied. The value of current and pH value were shown to produce a significant effect on electrolytic oxidation of BTEX. More than 95% of BTEX could be removed at 500 mA current within 8 hours. In the case of Fenton’s reaction it was established that more than 95% of BTEX could be removed at pH 4 with an addition of hydrogen peroxide in the amount of 12 mg/dm³. The treatment cost based on electrolytic oxidation amounted to between $0.04 and $5.1 USD/m³. For Fenton’s reaction, the treatment cost was between $0.16 and $0.65/m³. The costs of electrolytic oxidation and Fenton’s reaction were similar to the cost of electrodialysis and cheaper than the freeze–thaw and evaporation; however, these costs were higher than for air flotation and the use of anoxic/aerobic granular activated carbon.     

Indoor and outdoor carbonyl compounds and BTEX in the hospitals of Guangzhou, China

Indoor and outdoor concentration levels of 21 carbonyl compounds and five BTEX (benzene, toluene, ethylbenzene and xylenes) were measured in four hospitals of Guangzhou from 2nd January to 20th March 2004. Samples were collected in five consecutive daytimes for each hospital. Among most of the samples, acetone was the most abundant carbonyl, followed by acetaldehyde, 2-butanone or formaldehyde. Toluene was the most abundant BTEX and the others were at similar levels. The relatively higher acetone concentrations might have resulted from the high level of background in Guangzhou area due to emission of the factories and LPG-fuel vehicles, and also for the special weather conditions during sampling time. The high concentration of acetaldehyde, which was even higher than that of formaldehyde, might be resulted from the wide use of ethanol in hospital. The partial oxidation of ethanol may form acetaldehyde. The indoor concentrations of carbonyls and BTEX were found a little higher than their outdoor counterparts with only a few exceptions, which showed the anthropogenic sources for these compounds. The low correlations between most carbonyls and BTEX concentrations might be caused by their complex sources. Finally, the human exposure levels of formaldehyde and acetaldehyde in hospitals are discussed.     

Use of biomarkers in an indoor air study: lack of correlation between aromatic VOCs with respective urinary biomarkers

The benzene and toluene levels inside of eight homes with attached garages were measured during July 1998 in Fairbanks, Alaska. A thermal desorption tube method and charcoal tube method were used to collect and analyze samples (thermal desorption tube method %RDS = 1.9 for n = 6; charcoal tube method %RDS = 6.5 for n = 4). Results for both methods were compared and showed indoor benzene levels ranging between 1.2 and 72 ppbv. The charcoal tube method usually gave lower results than the thermal desorption method. Nevertheless, the difference observed in benzene levels from each method was not significant as determined by application of the Wilcoxon t-test to these data. Using the thermal desorption method, the range of toluene found in homes was 0.1-111 ppbv. A correlation between toluene and benzene levels suggested the same point source. The benzene and toluene content of the indoor air and the number of small engines stored in the attached garage was also correlated. There was no correlation found between the urinary biomarker concentrations and the level of benzene or toluene measured inside the homes in the summer.     

Long-term observations on the influence of groundwater level variations on BTEX concentrations in groundwater

A long-term study on natural attenuation and remediation in soil and groundwater at the former military base Schäferhof-Süd (Niedersachsen) was performed at a former gasoline filling station. At this locality, a large residual source of benzene, toluene, ethylbenzene, xylenes (BTEX) and additional petroleum hydrocarbons is present in the soil. BTEX-concentrations in the groundwater and their correlation with groundwater level variations were monitored for three years. Within the monitoring period, a very dry summer was recorded, which caused the groundwater level to drop by 1.7 m and the BTEX concentrations to increase from 240 µg/l to 1300 µg/l at the site of contamination. The microbial degradation of BTEX was documented by data on consumption of electron acceptors (oxygen, nitrate or sulphate) and production of reduced products (Fe(II), methane). The degradation is further supported by the detection of metabolites. Therefore, the increasing BTEX concentrations were not a consequence of limited biological degradation.     

Traffic-related air pollution and cardiovascular mortality in central Taiwan

In this study, the relationship between cardiovascular mortality and traffic-related air pollutants (NO₂, CO, PM₁₀, and six volatile organic compounds (VOCs), propane, iso-butane, propylene, benzene, meta-, para-, and ortho-xylenes) was investigated. The concentrations of NO₂, PM₁₀ and CO from 1993 to 2006 were measured at a fixed-site air monitoring station, and VOC data from 2003 to 2006 were obtained from a photochemical assessment monitoring site in an urban area in central Taiwan. Outcome variables were data on mortality due to cardiovascular diseases (ICD-9-CM 410-411, 414, 430-437) from 1993 to 2006. Cardiovascular mortality averaged 1.5 cases, ranging between 0 and 9 cases per day. Daily air pollution levels ranged from 0.5 to 80.5 ppb for NO₂ and from 0.1 to 3.8 ppm for CO. From the subset of data from 2003 to 2006, daily average values ranged from 0.6 to 17.5 ppb for propane, 0.3 to 6.7 ppb for iso-butane, 0.3 to 6.7 ppb for propylene, 0.2 to 3.8 ppb for benzene, 0.3 to 26.0 ppb for m,p-xylene, and 0.02 to 7.6 ppb for o-xylene. Poisson generalized additive model was used to estimate the effects of elevated air pollutant levels on daily mortality, adjusting for meteorological conditions and temporal trends. Single-pollutant model showed that cardiovascular mortality was significantly associated with NO₂ lagged 2 days, and with propane, iso-butane, and benzene lagged 0 day. The relative risk for an interquartile range increase in air pollutant levels was 1.053 for NO₂, 1.064 for propane, 1.055 for iso-butane, and 1.055 for benzene. In conclusion, daily cardiovascular mortality showed association with data on acute exposure to traffic air pollutants in Taichung, which is an important factor to consider in studying cardiovascular mortality in urban environments.     

Spatial and temporal trends of volatile organic compounds (VOC) in a rural area of northern Spain

Ambient concentrations of volatile organic compounds (VOCs) were measured at 40 rural sampling points in Navarre (northern Spain). Air samples were collected by means of sorbent passive sampling and analyzed by thermal desorption (TD) and gas chromatography/mass-selective detector (GC/MSD). A total of 140 VOCs were identified during the study, which was carried out between May to October 2004 for a total of a 10 biweekly sampling campaigns. Concentrations of benzene, toluene, ethylbenzene, m/p-xylenes, o-xylene (BTEX) and 1,3,5-trimethylbenzene were determined in order to investigate their temporal and spatial distributions. Geostatistical analysis pointed to traffic as the main emission source of these compounds. Supporting this idea, BTEX and nitrogen oxides concentrations were found to be highly significantly correlated (r = 0.495, P = 0.001), whereas a strong negative correlation between BTEX and ozone was also observed (r = -0.355, P = 0.025). The concentrations for the BTEX group were similar to the values that have been previously reported for other rural areas.     

BTEX biodegradation by bacteria from effluents of petroleum refinery

Groundwater contamination with benzene, toluene, ethylbenzene and xylene (BTEX) has been increasing, thus requiring an urgent development of methodologies that are able to remove or minimize the damages these compounds can cause to the environment. The biodegradation process using microorganisms has been regarded as an efficient technology to treat places contaminated with hydrocarbons, since they are able to biotransform and/or biodegrade target pollutants. To prove the efficiency of this process, besides chemical analysis, the use of biological assessments has been indicated. This work identified and selected BTEX-biodegrading microorganisms present in effluents from petroleum refinery, and evaluated the efficiency of microorganism biodegradation process for reducing genotoxic and mutagenic BTEX damage through two test-systems: Allium cepa and hepatoma tissue culture (HTC) cells. Five different non-biodegraded BTEX concentrations were evaluated in relation to biodegraded concentrations. The biodegradation process was performed in a BOD Trak Apparatus (HACH) for 20 days, using microorganisms pre-selected through enrichment. Although the biodegradation usually occurs by a consortium of different microorganisms, the consortium in this study was composed exclusively of five bacteria species and the bacteria Pseudomonas putida was held responsible for the BTEX biodegradation. The chemical analyses showed that BTEX was reduced in the biodegraded concentrations. The results obtained with genotoxicity assays, carried out with both A. cepa and HTC cells, showed that the biodegradation process was able to decrease the genotoxic damages of BTEX. By mutagenic tests, we observed a decrease in damage only to the A. cepa organism. Although no decrease in mutagenicity was observed for HTC cells, no increase of this effect after the biodegradation process was observed either. The application of pre-selected bacteria in biodegradation processes can represent a reliable and effective tool in the treatment of water contaminated with BTEX mixture. Therefore, the raw petroleum refinery effluent might be a source of hydrocarbon-biodegrading microorganisms.     

Indoor levels of volatile organic compounds at Florentine museum environments in Italy

Indoor Air Quality monitoring in cultural institutions is of particular concern to protect these places and the cultural heritage content. An indoor monitoring campaign was performed in three museums in Florence (Italy) to determine the occurrence and levels of volatile organic compounds (VOCs). VOCs of interest included BTEX (benzene, toluene, ethylbenzene, xylenes), terpenes, aldehydes, organic acids, and cyclic volatile methyl siloxanes (cVMS). The most abundant VOCs in all samples analyzed were BTEX, which were strictly related to the traffic source, followed by siloxanes and terpenes. Among BTEX, toluene was always the most abundant followed by xylenes, ethylbenzene, and benzene. cVMS in exhibition rooms with the presence of visitors showed higher values compared to samples collected when the museums were closed. Terpenes showed not only the influence of vegetation-biogenic sources surrounding a museum but could also be related to the wood used for the construction of showcases and furniture and the use of cleaning products. Data obtained also showed the presence of organic acids and aldehydes whose source can be traced back to exhibits themselves and wood-based furniture. Assessing the levels of organic acids in museums is important because, over time, it can cause deterioration of the artifacts.     

寒地污水厂曝气池VOCs逸散速率研究

本文以寒冷地区某城市污水处理厂曝气池作为研究对象,应用数学模型计算曝气池中苯系物(苯,甲苯,二甲苯)和氯代烃(三氯甲烷,四氯化碳,三氯乙烯,四氯乙烯)的逸散速率。计算结果表明寒冷地区污水处理厂苯系物和氯代烃在冬季的逸散速率最高。苯、甲苯、二甲苯、三氯甲烷、四氯化碳、三氯乙烯和四氯乙烯在冬季的逸散速率分别为5.22、0.37、0.46、1.46、1.18、18.92和2.22g/s。污水处理厂曝气池苯系物和氯代烃的排放标准满足《大气污染物综合排放标准(GB16297-1996)》。     

Effects of energy retrofits on Indoor Air Quality in multifamily buildings

We assessed 45 multifamily buildings (240 apartments) from Finland and 20 (96 apartments) from Lithuania, out of which 37 buildings in Finland and 15 buildings in Lithuania underwent energy retrofits. Building characteristics, retrofit activities, and energy consumption data were collected, and Indoor Air Quality (IAQ) parameters, including carbon monoxide (CO), nitrogen dioxide (NO₂), formaldehyde (CH₂O), selected volatile organic compounds (benzene, toluene, ethylbenzene, and xylenes (BTEX), radon, and microbial content in settled dust were measured before and after the retrofits. After the retrofits, heating energy consumption decreased by an average of 24% and 49% in Finnish and Lithuanian buildings, respectively. After the retrofits of Finnish buildings, there was a significant increase in BTEX concentrations (estimated mean increase of 2.5 µg/m³), whereas significant reductions were seen in fungal (0.6‐log reduction in cells/m²/d) and bacterial (0.6‐log reduction in gram‐positive and 0.9‐log reduction in gram‐negative bacterial cells/m²/d) concentrations. In Lithuanian buildings, radon concentrations were significantly increased (estimated mean increase of 13.8 Bq/m³) after the retrofits. Mechanical ventilation was associated with significantly lower CH₂O concentrations in Finnish buildings. The results and recommendations presented in this paper can inform building retrofit studies and other programs and policies aimed to improve indoor environment and health.