Preliminary investigations of pentachlorophenol emissions from biocide-treated masonry: a source of indoor air contamination

An empty, unoccupied basement room in Melton Constable Hall, Norfolk (England), was chosen as a case study to determine whether pentachlorophenol (PCP) treatment of masonry could significantly elevate PCP concentrations in indoor air, thus posing a potential health hazard. This particular room was chosen because it contained a vast quantity of crystalline PCP on the surface of a previously treated wall, and, being rarely used, was less likely to be subject to any external sources of PCP contamination. Analysis of dust debris, airborne particulates, passively deposited suspended particulates and volatile PCP emissions from the contaminated surface showed no evidence that inhalation was a probable route of PCP exposure.     

Children symptoms before and after knowing about an indoor fungal contamination

To describe children symptoms before and after an indoor fungal problem was publicized. Children attending one of two elementary schools (one with indoor fungal problems and one without) were included in this study. The study included an analysis of symptoms reported by the nurses before and after the indoor fungal problem was publicized and a questionnaire responded to by the parents. Several symptoms related to exposure to mold were found to be statistically significant in the school with an indoor fungal problem before the problem was detected: the symptoms included coughing/wheezing, headaches and joint pains. After the problem was publicized the perception of symptoms increased.     

21世纪环境岩土工程展望

论述了对环境岩土工程进行评价的重要性,同时讨论了常规岩土工程方法不适用研究土与环境相互作用问题的原因。阐述了笔者于80年代末提出的粒子能场理论,并特别强调其在敏感性生态岩土工程方面的应用:①土的干湿、胀缩和冻融循环机理;②土的污染和清污机理及过程;③放射性核废料和氡气的控制。最后,用两个最具挑战性的环境岩土工程为例来说明环境岩土工程问题的关联性和复杂性。     

Ozone in Residential Air: Concentrations,I/O Ratios,Indoor Chemistry,and Exposures

Ozone concentrations were measured in indoor and outdoor residential air during the summer of 1992. Six homes located in a New Jersey suburban area were chosen for analysis, and each home was monitored for 6 days under different ventilation and indoor combustion conditions. The 5-hour average ozone concentration outdoors over the monitoring period was 95 ± 36 ppbv. One third of the days exceeded the National Ambient Air Quality Standard (NAAQS), one-hour maximum concentration of 120 ppb. The mean indoor to outdoor (I/O) ratios of ozone concentration ranged from 0.22 ± 0.09 to 0.62 ± 0.11, depending upon ventilation rate and indoor gas combustion. The presence of indoor gas combustion can significantly decrease the I/O ratio. Because of the great amount of time that people spend indoors, the indoor residential exposures were estimated to account for 57% of the total residential exposures. One type of the possible gas-phase reactions for indoor ozone, the reaction of ozone with a volatile organic compound containing unsaturated carbon-carbon bonds, is discussed with some supporting evidence provided in the study.     

Radiochemical indoor environment and possible health risks in current building technology

Tremendous work of civil and environmental engineering has been focused on development of sustainable buildings. From economical and ecological viewpoint, this approach is a significant step forward, but the microenvironment created in such living surroundings may present a complex radiochemical setting, which could be a threat to the health of its occupants. This paper gives overview about levels of indoor radon, insight in risks related with radioactivity of fly ash and zircon, current application of nanoparticles and concrete additives in buildings and their possible impact on human health. As construction engineering is current producer of almost 50% of waste encouragement of incorporation of toxic and radioactive agents in buildings could in future demand redefinition of building construction waste as hazardous and special waste disposals. Collaboration between governmental and non-governmental bodies, manufacturers, scientific institutions, and chartered engineers is needed in order to find balance between quality of indoor air, and to enable maintaining of high health standards by application of non-toxic or non-carcinogenic building materials that meet energy efficiency, building structure stability and security requirements.     

Relative Effectiveness of Sub-slab Pressurization and Depressurization Systems for Indoor Radon Mitigation: Studies with an Experimentally Verified Numerical Model

The performance of sub-slab-ventilation (SSV) systems has been parametrically studied with a numerical model that was earlier compared successfully with experiment ( Bonnefous et al., 1992 ). The model distinguishes between the sub-slab gravel and the underlying soil. It is used w examine system performance for the following system parameters: the permeability of the soil and of the sub-slab gravel, the magnitude of pressurization (or depressurization) applied by the SSV system, and the mode of SSV application (i.e. pressurization (SSP) or depressurization (SSD)). The mechanisms contributing to the successful performance of SSP and SSD systems are identified. For SSD systems, the mechanisms are (1) the inversion of the pressure gradient across the basement slab, and (2) the reduction of the radon concentration in the soil. For SSP systems, the mechanisms are (1) the elimination of convective flow of soil-gas from the soil into the sub-slab gravel by pressurization of the sub-slab region, (2) the reduction of the radon concentration in the soil, and (3) the suppression of diffusion of soil-gas from the soil into the sub-slab gravel by advective flow of air from the gravel bed into the subgravel soil. Numerical modeling demonstrates that placement of a sub-slab gravel layer substantially improves the SSV system performance. Except in the case of highly permeable soils, SSD systems are predicted to perform better than SSP systems. This prediction is consistent with reported field experience. The numerical model is used to elucidate the reasons for this difference in performance.     

Modeling ventilation and radon in new Dutch dwellings

Indoor radon concentrations were estimated for various ventilation conditions, the differences being mainly related to the airtightness of the dwelling and the ventilation behavior of its occupants. The estimations were aimed at describing the variation in air change rates and radon concentrations to be expected in the representative newly built Dutch dwellings and identifying the most important parameters determining air change rate and indoor radon concentration. The model estimations were compared with measurements. Most of the air was predicted to enter the model dwelling through leaks in the building shell, independent of the ventilation conditions of the dwelling. Opening the air inlets was shown to be an efficient way to increase infiltration and thus to decrease radon concentration. The effect of increasing the mechanical ventilation rate was considerably less than opening the air inlets. The mechanical ventilation sets the lower limit to the air change rate of the dwelling, and is effective in reducing the radon concentration when natural infiltration is low. Opening inside doors proved to be effective in preventing peak concentrations in poorly ventilated rooms. As the airtightness of newly built dwellings is still being improved, higher radon concentrations are to be expected in the near future and the effect of occupant behavior on indoor radon concentrations is likely to increase. According to the model estimations soil-borne radon played a moderate role, which is in line with measurements.     

Radon in indoor air of primary schools: a systematic survey to evaluate factors affecting radon concentration levels and their variability

In order to optimize the design of a national survey aimed to evaluate radon exposure of children in schools in Serbia, a pilot study was carried out in all the 334 primary schools of 13 municipalities of Southern Serbia. Based on data from passive measurements, rooms with annual radon concentration >300 Bq/m³ were found in 5% of schools. The mean annual radon concentration weighted with the number of pupils is 73 Bq/m³, 39% lower than the unweighted 119 Bq/m³ average concentration. The actual average concentration when children are in classrooms could be substantially lower. Variability between schools (CV = 65%), between floors (CV = 24%) and between rooms at the same floor (CV = 21%) was analyzed. The impact of school location, floor, and room usage on radon concentration was also assessed (with similar results) by univariate and multivariate analyses. On average, radon concentration in schools within towns is a factor of 0.60 lower than in villages and at higher floors is a factor of 0.68 lower than ground floor. Results can be useful for other countries with similar soil and building characteristics.     

Health and social impacts of improved stoves on rural women: a pilot intervention in Sindh, Pakistan

To assess the acceptability, social and health impacts of improved stoves among women. A cross-sectional study was conducted from April to May 2002 among households using improved stoves in the two villages of District Thatta and Hyderabad, Sindh, Pakistan. A questionnaire was administered to 45 women using improved stoves named Smoke Free Stoves (SFS). The same questionnaire was administered to a sample of 114 women, using Traditional Stoves (TS). Carbon monoxide (CO) levels were measured in a sample of both groups. Multivariate analysis was carried out to adjust for confounders. In addition, focus group discussions (FGDs) were conducted to evaluate the perception of women regarding acceptability and impact of SFS on women. A majority of women reported that SFS produce less smoke and have a beneficial impact on their health. In the multivariate analysis, symptoms of dry cough (AOR=0.61; 95% CI 0.26-1.41), sneezing (AOR=0.54; 95% CI 0.22-1.30) and tears while cooking (TWC) (AOR=0.51; 95% CI 0.21-1.21) are less likely to occur in women using SFS compared to TS. However, the results were not statistically significant possibly due to the small sample. The mean (+/-s.e.) CO levels were 15.4+/-3.4 ppm in SFS and 28.5+/-5.7 ppm in TS kitchens with a mean difference of -13.1 (95% CI -29.5 and 3.2). The results indicate a trend favorable for SFS and suggest that a larger scale project should be undertaken to reach to a definitive conclusion, ideally using a longitudinal design. PRACTICAL IMPLICATIONS: In order to enhance IAQ in kitchens in developing regions of the world stoves for burning of biomass should be constructed in a way that the emission of fuel gases are low. In this way the risk of negative health effects will be reduced.     

Physico-chemical characterization of indoor/outdoor particulate matter in two residential houses in Oslo, Norway: measurements overview and physical properties--URBAN-AEROSOL Project

Indoor/outdoor measurements have been performed in the Oslo metropolitan area during summer and winter periods (2002-2003) at two different residential houses. The objective of the measurement study was to characterize, physically and chemically, the particulate matter (PM) and gaseous pollutants associated with actual human exposure in the selected places, and their indoor/outdoor relationship. In this paper, we focus on the PM measurements and examine the relationship between the indoor and outdoor PM concentrations taking into account the ventilation rate, indoor sources and meteorological conditions. The indoor/outdoor measurements indicate the important contribution of the outdoor air to the indoor air quality and the influence of specific indoor sources such as smoking and cooking to the concentration of PM inside houses. However, no specific correlation was found between the indoor/outdoor concentration ratio and the meteorological parameters. This study provides information on the physical characteristics and the relationship of indoor to outdoor concentration of particulate matter in residential houses. Moreover, the parameters that influence this relationship are discussed. The results presented here are specific to the sampled houses and conditions used and provide data on the actual human exposure characteristics which occur in the spatial and temporal scales of the present study.     

Polycyclic aromatic hydrocarbons: levels and phase distributions in preschool microenvironment

This work aims to characterize levels and phase distribution of polycyclic aromatic hydrocarbons (PAHs) in indoor air of preschool environment and to assess the impact of outdoor PAH emissions to indoor environment. Gaseous and particulate (PM₁ and PM_2.5) PAHs (16 USEPA priority pollutants, plus dibenzo[a,l]pyrene, and benzo[j]fluoranthene) were concurrently sampled indoors and outdoors in one urban preschool located in north of Portugal for 35 days. The total concentration of 18 PAHs (ΣPAHs) in indoor air ranged from 19.5 to 82.0 ng/m³; gaseous compounds (range of 14.1–66.1 ng/m³) accounted for 85% ΣPAHs. Particulate PAHs (range 0.7–15.9 ng/m³) were predominantly associated with PM₁ (76% particulate ΣPAHs) with 5‐ring PAHs being the most abundant. Mean indoor/outdoor ratios (I/O) of individual PAHs indicated that outdoor emissions significantly contributed to PAH indoors; emissions from motor vehicles and fuel burning were the major sources.     

Prediction of residential radon exposure of the whole Swiss population: comparison of model‐based predictions with measurement‐based predictions

Radon plays an important role for human exposure to natural sources of ionizing radiation. The aim of this article is to compare two approaches to estimate mean radon exposure in the Swiss population: model‐based predictions at individual level and measurement‐based predictions based on measurements aggregated at municipality level. A nationwide model was used to predict radon levels in each household and for each individual based on the corresponding tectonic unit, building age, building type, soil texture, degree of urbanization, and floor. Measurement‐based predictions were carried out within a health impact assessment on residential radon and lung cancer. Mean measured radon levels were corrected for the average floor distribution and weighted with population size of each municipality. Model‐based predictions yielded a mean radon exposure of the Swiss population of 84.1 Bq/m³. Measurement‐based predictions yielded an average exposure of 78 Bq/m³. This study demonstrates that the model‐ and the measurement‐based predictions provided similar results. The advantage of the measurement‐based approach is its simplicity, which is sufficient for assessing exposure distribution in a population. The model‐based approach allows predicting radon levels at specific sites, which is needed in an epidemiological study, and the results do not depend on how the measurement sites have been selected.     

原人工制气厂土壤修复技术及经济比较

结合国外情况指出了原人工制气厂的土壤修复问题。论述了治理被多环芳烃、废脱硫剂等化学物质污染土壤的修复技术及处理效果,对各种方法的修复费用和时间进行了比较。     

Sensory Pollution and Microbial Contamination of Ventilation Filters

Abstract The sensory pollution load and microbial contamination of glass-fibre filters at high and low relative humidity were investigated in an experimental set-up in the laboratory. Dust and particles from the outdoor air were collected in two EU7 glass-fibre filters for a pre-conditioning period of 16–18 weeks during which there was a constant airflow with a velocity of 1.9 m/s through the filters. One of the filters was exposed to outdoor air of approximately 40% relative humidity and 10°C, the other to outdoor air of approximately 80% relative humidity and 5°C. The dust in ventilation filters can constitute a serious pollution source in the indoor environment, causing deterioration in the quality of the supply air even before it enters the ventilated spaces. The sensory pollution load from the used filters after the continuous operating time of 16–18 weeks was significantly higher than the sensory pollution load from new filters but the sensory load at 40% and 80% relative humidity did not differ. The microbial contamination of the supply air downstream of the filters, which on average had been exposed to outdoor air of 40% and 80% relative humidity, was negligible.     

Indoor air quality in Portuguese schools: levels and sources of pollutants

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM_2.5, PM₁₀, bacteria and fungi, carbon dioxide (CO₂), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO₂ and occupancy data. Concentrations of CO₂ exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m³) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO₂ levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools.     

Defects and moisture problems in buildings from historical city centres: a case study in Portugal

Conservation of ancient buildings is a major issue for modern societies, both from economical and cultural viewpoints. Information about the ancient built heritage is vital to plan adequate remedial measures. Taking a historic centre in Portugal as a case study, this paper presents an extensive survey of building typology and materials, damage in the building envelope, indoor survey of damage, and measurements in indoor air temperature and relative humidity. Water-related problems can be confirmed as the single most important defect combined with inadequate sun exposure, ventilation and heating, and excessive moisture indoor production. Extremely low temperatures, high humidity and presence of mould therefore, compromise the indoor quality of life of the inhabitants; and make urgent repair at many levels necessary.     

Methanol exposure to car occupants from windshield washing fluid: a pilot study

Automobile occupants might be exposed to considerable amounts of methanol from previously unreported source, namely via the inhalation of vapors of winter-grade, methanol-based, windshield washing fluid that drains to the intake air ducts of the car. Air samples were collected in passenger cars during simulated operating conditions and analyzed for methanol via headspace gas chromatography-mass spectrometry, electron impact, selected ion monitoring. The method was linear in the 2-2000 ppm range. Concentrations exceeding 1000 ppm were recorded. PRACTICAL IMPLICATIONS: Using a winter-grade, methanol-based, windshield washing fluid for windshield cleaning in a passenger car can result in a methanol concentration in the air of the passenger cabin in excess of 1000 ppm. In view of the widespread use of this product, more studies are necessary to elucidate, in depth, the concentrations of methanol vapors which could be encountered in various weather and driving conditions as well as the concomitant contributing influences of car design. These studies are necessary to properly assess the hazards associated with use of the fluid and possible mitigation approaches which might include substitution of methanol by less toxic formulations.     

Indoor 222Rn in Tennessee Valley Houses: Seasonal,Building, and Geological Factors

A two-season survey of indoor ²²²Rn concentrations was conducted in 226 occupied houses in Roane County, TN, during 1985 and 1986. A similar survey of 86 houses in Madison County, AL, was conducted in 1988 and 1989. Alpha track detectors were placed in each of the houses for three or more months during the winter heating season. Detectors were placed at the same sampling sites during the following cooling season. In this study, comparisons were made between winter and summer sampling times and between building types. For the data from Madison County, additional comparisons were made among regions of the county that differed in geological characteristics, especially the thickness of overburden above the Chattanooga Shale layer a geological stratum that has high concentrations of ²²⁶Ra and is widely found in the southeastern United States. The geometric means of summer and winter measurements in Roane County were 33 and 54 Bq m^?3, respectively. For Madison County, the summer and winter geometric means were 121 and 88 Bq m^?3, respectively. The winter ²²²Rn concentrations for houses in Roane Coutuy exceeded summer ²²²Rn concentrations, as is generally the case for houses in the US. For houses in Madison County, we found the opposite and atypical situation of higher ²²²Rn concentrations in the summertime. ²²²Rn concentrations differed significantly among groups of houses in distinguishable regions of Madison County. Substructure and other building factors had no observable effect on indoor ²²²Rn concentrations found in this study.     

China's fuel gas sector: History,current status,and future prospects

China has a unique urban pipeline network of three types of fuel gases: manufactured gas (coal gas), Liquefied Petroleum Gas (LPG), and natural gas. Manufactured gas, which is often seen as an outdated technology in the western world, is still widely used in Chinese cities. LPG is distributed through community-based pipelines in many Chinese cities, in addition to its distribution in cylinders and canisters in rural areas. Natural gas consumption is increasing throughout China, particularly as a cooking fuel. Expanding the production and supply of natural gas in China faces many challenges. In particular, China's controls on natural gas prices have deterred investment in exploration and natural gas imports. However, recent price decontrols of unconventional natural gas (defined in Chinas as shale gas, coal-bed methane, and coal-to-natural-gas), and recent pricing reforms, appear likely to increase natural gas use. The prospect for increased exploration is promising but will still depend greatly on the future of institutional reforms. In the near term, regulatory reforms toward a more market-driven system will be the most critical issue in the development of China's fuel gas sector.     

Allergy and respiratory health effects of dampness and dampness‐related agents in schools and homes: a cross‐sectional study in Danish pupils

Little is known about the health effects of school‐related indoor dampness and microbial exposures. In this study, we investigated dampness and dampness‐related agents in both homes and schools and their association with allergy and respiratory health effects in 330 Danish pupils. Classroom dampness was identified based on technical inspection and bedroom dampness on parents' self‐report. Classroom and bedroom dust was analyzed for seven microbial components. Skin prick testing determined atopic sensitization. Lung function was expressed as z‐scores for forced expiratory volume in one‐second (zFEV₁), forced vital capacity (zFVC) and the ratio zFEV₁/zFVC using GLI‐2012 prediction equations. The parents reported children's allergies, airway symptoms, and doctor‐diagnosed asthma. High classroom dampness, but not bedroom dampness, was negatively associated with zFEV₁ (β‐coef. ?0.71; 95% CI ?1.17 to ?0.23) and zFVC (β‐coef. ?0.52; 95% CI ?0.98 to ?0.06) and positively with wheezing (OR 8.09; 95% CI 1.49 to 43.97). No consistent findings were found between any individual microbial components or combination of microbial components and health outcomes. Among other indoor risk factors, environmental tobacco smoke (ETS) decreased zFEV₁ (β‐coef. ?0.22; 95% CI ?0.42 to ?0.02) and zFEV₁/zFVCratio (β‐coef. ?0.26; 95% CI ?0.44 to ?0.07) and increased upper airway symptoms (OR 1.66; 95% CI 1.03–2.66). In conclusion, dampness in classrooms may have adverse respiratory health effects in pupils, but microbial agents responsible for this effect remain unknown.