Distribution of 2,4-D in air and on surfaces inside residences after lawn applications: comparing exposure estimates from various media for young children.

We collected indoor air, surface wipes (floors, table tops, and window sills), and floor dust samples at multiple locations within 11 occupied and two unoccupied homes both before and after lawn application of the herbicide 2,4-D. We measured residues 1 week before and after application. We used collected samples to determine transport routes of 2,4-D from the lawn into the homes, its subsequent distribution between the indoor surfaces, and air concentration as a function of airborne particle size. We used residue measurements to estimate potential exposures within these homes. After lawn application, 2,4-D was detected in indoor air and on all surfaces throughout all homes. Track-in by an active dog and by the homeowner applicator were the most significant factors for intrusion. Resuspension of floor dust was the major source of 2,4-D in indoor air, with highest levels of 2,4-D found in the particle size range of 2.5-10 microm. Resuspended floor dust was also a major source of 2,4-D on tables and window sills. Estimated postapplication indoor exposure levels for young children from nondietary ingestion may be 1-10 microg/day from contact with floors, and 0.2-30 microg/day from contact with table tops. These are estimated to be about 10 times higher than the preapplication exposures. By comparison, dietary ingestion of 2,4-D is approximately 1.3 microg/day.     

Evaluation and determinants of airborne bacterial concentrations in school classrooms

A survey of 39 elementary schools was undertaken to determine indoor air concentrations of bioaerosols within a coastal, temperate climatic zone in British Columbia, Canada. This article reports the results for airborne bacteria. Determinants of exposure were grouped into environmental (outdoor temperature, relative humidity, season, weather), ventilation and comfort parameter (indoor relative humidity, temperature, indoor CO2 concentration, indoor fungal concentration), and occupancy (number of occupants, activity levels, occupancy patterns) variables. Regression modeling was used to evaluate the association between these factors and measured concentrations of indoor mesophilic bacteria. Naturally ventilated rooms (47% of the total rooms surveyed) had higher bacterial counts than mechanically ventilated rooms (geometric mean 325 vs. 166 CFU/m3, respectively, p < 0.001). In univariate analyses, bacterial counts were negatively correlated with supply and exhaust flow rates, air exchange rates, and the percentage of the day that occupants spent quietly sitting at their desks. Analysis of bacterial groups indicated various sources of the bacterial aerosol, with micrococci and staphylococci closely associated with occupancy variables, Bacillus with site and occupancy, and coryneform bacteria with site variables only. Approximately 60% of the variance in the outcome measurement of total bacteria was accountedfor by indoor CO2, lower air exchange rate, the age of the building, signs of current or old moisture stains, room volume, indoor relative humidity, and occupant activity level in a multiple linear regression model, with ventilation factors accounting for 40% of the variance.     

Indoor particles and symptoms among office workers: results from a double-blind cross-over study

BACKGROUND: We studied the effects of removing small airborne particles in an office building without unusual contaminant sources or occupant complaints. METHODS: We conducted a double-blind crossover study of enhanced particle filtration in an office building in the Midwest United States in 1993. We replaced standard particle filters, in separate ventilation systems on two floors, with highly efficient filters on alternate floors weekly over 4 weeks. Repeated-measures models were used to analyze data from weekly worker questionnaires and multiple environmental measurements. RESULTS: Bioaerosol concentrations were low. Enhanced filtration reduced concentrations of the smallest airborne particles by 94%. This reduction was not associated with reduced symptoms among the 396 respondents, but three performance-related mental states improved; for example, the confusion scale decreased (-3.7%; 95% confidence limits (CL) = -6.5, -0.9). Most environmental dissatisfaction variables also improved; eg, "stuffy" air, -5.3% (95% CL = -10.3, -0.4). Cooler temperatures within the recommended comfort range were associated with remarkably large improvement in most outcomes; for example, chest tightness decreased -23.4% (95% CL = -38.1, -8.7) for every 1 degrees C decrease. CONCLUSIONS: Benefits of enhanced filtration require assessment in buildings with higher particulate contaminant levels in studies controlling for temperature effects. Benefits from lower indoor temperatures need confirmation.     

Investigation of air pollution in a shopping center and employees' personal exposure level

OBJECTIVES: To investigate the concentrations of chemicals found inside a shopping center (SC), we investigated the condition of air pollution in a SC and the personal exposure level of SC employees. METHODS: The survey was performed in June 2006 in Kyushu. The chemicals studied were volatile organic compounds (VOCs) and aldehydes. The chemicals were collected by a personal passive sampler. RESULT: Thirty-one VOCs and aldehydes were detected inside the SC. The results showed that the concentrations of all the chemicals detected in indoor air were less than those specified in the indoor air quality guideline of Ministry of Health, Labor and Welfare, Japan. The chemical concentrations in the SC decreased in the order of food corner > electric, clothing corner > outdoor and were clearly higher than those outdoors. Therefore, it is thought that the source of chemicals is indoors. The high indoor concentration of 2-ethyl-1-hexanol may be due to diffusion from the walls and floors. In addition, it is suggested that the personal exposure condition of the employees reflected the indoor concentration of each sales floor. The exposure level to formaldehyde was higher at nonworking time than at working time, suggesting that a larger exposure source exists in the place of residence than in the work place. CONCLUSIONS: We found that indoor air quality in SC is maintained at good levels. This might be because of the Japanese strict regulations that require administrations of large-scale buildings to provide adequate ventilation and perform regular measurement of indoor air quality.     

Chemical and microbial exposures in a school building: adverse health effects in children

In this cross-sectional study, the authors examined the relationship between an unusual combination of indoor air contaminants in a school and adverse health effects among the attending children. A leaking roof and damp floors, together with gaseous leaks from the sewage system, led to a combined exposure of hydrocarbons, 2-ethylhexanol from plastic floor coverings, and moisture-associated microbes. The health status of 274 children in the school was assessed via repeated symptom questionnaires. Statistical analysis revealed a relationship between the indoor air contaminants and adverse health outcomes such as respiratory irritation, asthmatic symptoms, eye and general symptoms, and increased occurrence of common viral respiratory infections. No association was found between the exposures and doctor-diagnosed asthma, other allergic diseases, or bacterial respiratory infections. Chemical contaminants from the sewer system and damp construction materials were identified as the source of the problem. Remediation of the school building improved the indoor air quality and the health status of the children.     

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study

OBJECTIVES: The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination. METHODS: GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi. RESULTS: Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on. CONCLUSION: Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

 

     

Indoor air pollution in newly built or renovated elementary schools and its effects on health in children

PURPOSE: To elucidate the actual status of indoor air pollution at newly built or renovated elementary schools, and to evaluate its effects on health symptoms in the affected children. METHODS: In the classrooms of four newly built or renovated elementary schools in Osaka Prefecture, indoor air levels of formaldehyde and volatile organic compounds (VOC) were measured immediately, 1 month, 3 months, 10 months and 22 months after the completion of the construction work. Also, questionnaire surveys regarding subjective symptoms of sick building syndrome were conducted before and after the renovation on the children who attended classes in the renovated rooms. RESULTS: In the newly built computer classroom, more formaldehyde was detected one month after the completion of the construction work, when computers and furniture were carried in, than immediately after the completion of the work. Then, during the summer season, even 10 months and 22 months after completion of the new building, formaldehyde above the guideline values was detected. In the renovated common classrooms, the formaldehyde level was the same as that in the classrooms which did not undergo renovation, but VOC levels were higher immediately after the completion of the construction work, and the toluene level was above the guideline value. In 4-story reinforced concrete school buildings, indoor air pollution tended to be higher on the third and the fourth floors than on the first and the second floors. In 3-story school buildings, indoor air pollution tended to be higher on the third floor than on the second floor. The survey of subjective symptoms of the children revealed a tendency toward an increase in the prevalence of sick building syndrome after a renovation. However, the actual number of the children complaining of the symptoms hardly changed. Instead, the number of symptoms for each subject increased, and this increase was significant in 5th and 6th grade boys. CONCLUSION: In the some classrooms of newly built or renovated elementary schools, chemical substances above the guideline values may be detected. In such classrooms, more ventilation is required.     

Dynamics of Rn transport from the cellar to the living area in an unheated house.

Environmental parameters such as temperature and wind, occupant activities, and house-specific parameters such as subsoil geology, leakiness of the substructure to soil gas, and air exchange rate are the main factors influencing Rn entry into a building and its subsequent indoor behavior. Experiments performed in an unheated, uninhabited house showed a reproducible diurnal fluctuation of the indoor concentration of Rn decay products. Strong, long-term correlations between temperature differences indoor-outdoor (indoor temperature minus outdoor temperature) and pressure differences outdoor-indoor (outdoor pressure minus indoor pressure) were found. At positive temperature differences inside-outside, an average airflow velocity of about 0.05 m s-1 between ground floor and first floor was detected. This air movement was able to vertically transport Rn at a rate of approximately 11 kBq h-1 in a volume of air of about 5.5 m3 through a cross-sectional area of only 0.03 m2. For this specific house, stack effects were identified as the main driving force for Rn migration from the cellular to higher floors. The diurnal fluctuation of Rn progeny concentrations in the living area can be explained by temporal variations in the amount of Rn-rich air transported vertically from the cellar into the building as a consequence of stack effects.     

Temporal and spatial distributions of aerial contaminants in an enclosed pig building in winter

Optimal management of indoor air quality in an enclosed swine house, especially in winter, is indispensable for preventing the transmission of infectious respiratory disease to workers and animals. Studies are needed to elucidate the correlation of aerial contaminants and climate factors. It was observed that indoor air contamination in an enclosed pig building was the highest at 2:00--5:00 PM, followed by 8:00--11:00 PM and 8:00--11:00 AM. It was assumed that this was attributed to the increase of swine activities in the afternoon. In general, the concentration of total dust and total airborne bacteria in an enclosed pig building was found to have a significant correlation with temperature and relative humidity (P<0.05). There were significant correlations between total dust and total airborne bacteria, between total dust and ammonia, and between total dust and odor at the 95% confidence level. In conclusion, temperature and total dust concentration correlated significantly with all parameters except hydrogen sulfide (H(2)S). This could have been due to the drying of swine feces due to the increase in interior temperature and the resuspension of feed deposited on the floor of the pig building by the swines' activity, resulting in a high generation of dust that adsorbed and carried the airborne bacteria and odorous compounds in the enclosed pig building. It was proved that an adsorptive capacity of dust for ammonia was higher than for hydrogen sulfide.     

Lead exposures from varnished floor refinishing

We evaluated the presence of lead in varnish and factors predicting lead exposure from floor refinishing and inexpensive dust suppression control methods. Lead in varnish, settled dust, and air were measured using XRF, laboratory analysis of scrape and wipe samples, and National Institute for Occupational Safety and Health (NIOSH) Method 7300, respectively, during refinishing (n = 35 homes). Data were analyzed using step-wise logistic regression. Compared with federal standards, no lead in varnish samples exceeded 1.0 mg/cm(2), but 52% exceeded 5000 ppm and 70% of settled dust samples after refinishing exceeded 40 μg/ft(2). Refinishing pre-1930 dwellings or stairs predicted high lead dust on floors. Laboratory analysis of lead in varnish was significantly correlated with airborne lead (r = 0.23, p = 0.014). Adding dust collection bags into drum sanders and HEPA vacuums to edgers and buffers reduced mean floor lead dust by 8293 μg Pb/ft(2) (p<0.05) on floors and reduced most airborne lead exposures to less than 50 μg/m(3). Refinishing varnished surfaces in older housing produces high but controllable lead exposures.     

Longitudinal study of dust and airborne endotoxin in the home

To characterize the seasonal variability of endotoxin levels, we measured endotoxin in dust from the bed, bedroom floor, and kitchen floor in 20 homes, and in air from the bedroom in 15 of the homes. All homes were located in the greater Boston, Massachusetts, area and were sampled each month from April 1995 to June 1996. Outdoor air was collected at two locations. We found greater within-home than between-home variance for bedroom floor, kitchen floor, and airborne endotoxin. However, the reverse was true for bed dust endotoxin. Thus, studies using single measurements of dust endotoxin are most likely to reliably distinguish between homes if bed dust is sampled. Dust endotoxin levels were not significantly associated with airborne endotoxin. Airborne endotoxin was significantly (p = 0. 04) and positively associated with absolute humidity in a mixed-effect model adjusting for a random home effect and fixed effect of sampling month and home characteristics. This finding implies that indoor humidity may be an important factor controlling endotoxin exposure. We found a significant (p < 0.05) seasonal effect in kitchen floor dust (spring > fall) and bedroom airborne endotoxin (spring > winter), but not in the other indoor samples. We found significant seasonal pattern in outdoor airborne endotoxin (summer > winter).     

Building-specific factors affecting indoor radon concentration variations in different regions in Bulgaria

The study was conducted to assess the spatiality of the building factors’ effect on air quality through evaluation of indoor radon concentration in areas with different geology and geographical position. For that matter, a survey of indoor radon concentration was carried out in 174 kindergartens of three Bulgarian cities. The time-integrated measurements were performed in 777 ground floor rooms using alpha tract detectors, exposed for 3 months in cold period of 2014. The results of indoor radon concentrations vary from 20 to 1117 Bq/m³. The differences in the mean radon concentrations measured in the different cities were related to geology. The effect of building-specific factors: elevator, basement, mechanical ventilation, type of windows, number of floors, building renovation, building materials, type of room, type of heating, construction period, and availability of foundation on radon concentration variations was examined applying univariate and multivariate analysis. Univariate analysis showed that the effects of building-specific factors on radon variation are different in different cities. The influence of building factors on radon concentration variations was more dominant in inland cities in comparison to the city situated on the sea coast. The multivariate analysis, which was applied to evaluate the impact of building factors simultaneously, confirmed this influence too.     

Evaluation and a predictive model of airborne fungal concentrations in school classrooms

Exposure to airborne fungal products may be associated with health effects ranging from non-specific irritation of the respiratory tract or mucus membranes to inflammation provoked by specific fungal antigens. While concentrations of airborne fungi are frequently measured in indoor air quality investigations, the significance of these measurements in the absence of visual mold colonization is unclear. This study was undertaken to evaluate concentrations of airborne fungal concentrations in school classrooms within a defined geographic location in British Columbia, Canada, and to build a model to clarify determinants of airborne fungal concentration. All elementary schools within one school district participated in the study. Classrooms examined varied by age, construction and presence or absence of mechanical ventilation. Airborne fungal propagules were collected inside classrooms and outdoors. Variables describing characteristics of the environment, buildings and occupants were measured and used to construct a predictive model of fungal concentration. The classrooms studied were not visibly contaminated by fungal growth. The data were evaluated using available guidelines. However, the published guidelines did not take into account significant aspects of the local environment. For example, there was a statistically significant effect of season on the fungal concentrations and on the proportional representation of fungal genera. Rooms ventilated by mechanical means had significantly lower geometric mean concentrations than naturally ventilated rooms. Environmental (temperature, outdoor fungal concentration), building (age) and ventilation variables accounted for 58% of the variation in the measured fungal concentrations. A methodology is proposed for the evaluation of airborne fungal concentration data which takes into account local environmental conditions as an aid in the evaluation of fungal bioaerosols in public buildings.     

Organochlorine pesticide exposure and uptake following treatment of domestic premises: Data from the first 6 months of follow‐up

Twenty-nine dwellings treated with aldrin in a standard manner for prevention of termite infestation, are being repeatedly sampled over a 2‐year period for airborne aldrin concentrations. Air sampling is being carried out under standardized conditions with the doors and windows of the sampled room closed to maximize the estimated airborne exposure to the occupants. Periodic measurements are also being made of blood dieldrin levels of one occupant of each dwelling. Blood and air levels in the first 6 months of the study have been recorded, and in summary were:

The data show that domestic aldrin treatment, even when performed under regulated conditions by licensed, trained operators, results in widely-varying degrees of internal contamination of the house. Using the mean of the three post-treatment aldrin air concentrations as an approximate index of air contamination, only the' most heavily contaminated dwellings have appeared to cause a clearly perceptible increase in blood dieldrin. In the two most extreme cases, mean aldrin concentrations of 46 and 32 μg m^-3 were associated with increases in blood dieldrin concentrations of 4.8 and 4.7 ng ml^-1 respectively. In view of the wide variation in atmospheric levels, further studies are planned, to include an analysis of what structural features of houses and the underlying soil are likely to be associated with high air levels.     

Role of the number of stories in the radiation-sanitary assessment of residential buildings

Upon long-term exposure, the radioactive gas radon-222 and its decay products in increased doses adversely affect human health. Since the human being spends about 65% of his time in the buildings, it is necessary to evaluate air radiation purity in the rooms, which can be obtained by making a sanitary radiological survey of residential buildings. The scope of the rooms in many-storeyed buildings to be examined can be considerably reduced if the regularities in radon distribution are known. This paper deals with searches for regularities in the distribution of radon levels by the floors of many-storeyed buildings in Tomsk. The room air concentrations of radon were measured for 18 residential buildings with tract detectors upon 1-3--month exposure. The findings showed a different pattern in the distribution of radon levels by the floors in relation to the structural features of a building and to the type of a building material. The wooden and slag-concrete buildings show a 2-3--fold increase in radon levels on the lower floors as compared to the upper ones. A statistical analysis of measurements in the bearing-wall and brick buildings revealed no association of the concentration of radon with the level of a floor, the distribution is near-uniform with 15-30% standard deviation, which is within the limits of measurement error.     

Evaluation of source model coupled computational fluid dynamics (CFD) simulation of the dispersion of airborne contaminants in a work environment

Dispersion of airborne contaminants in indoor air was evaluated employing physical measurement, empirical models, and computer simulation methods. Field data collected from a tray of evaporating solvent in the laboratory were compared with computational fluid dynamics (CFD) simulations coupled with evaporation models. The results indicated that mathematical models of evaporation can be coupled with CFD simulations to produce reasonable qualitative predictions of airborne contaminant levels. The airflow pattern within a room is primarily determined by the room layout and the position of the air supply diffusers. Variations in ventilation rate did not alter the airflow pattern, thus generating a characteristic concentration profile of the airborne contaminants.     

Residential indoor air contamination by screen printing plants

Summary The presence of organic solvents was investigated by means of environmental monitoring of the indoor air during one workweek in each of ten selected small screen printing plants and the houses surrounding them in the inner city of Amsterdam. In the indoor air of the screen printing plants, 14 to 17 organic solvents were identified. The concentrations of the identified organic solvents varied widely from sampling location and period. In the indoor air of the houses situated above the plants, zero to fifteen organic solvents were identified. The concentration of organic solvents in the indoor air of the houses situated above was related to the type of construction materials. The highest concentrations were found in the houses situated above moderately maintained screen printing plants with wooden floors and ceilings (n = 5). The concentration of organic solvents in the indoor air of the houses situated above well maintained screen printing plants with wooden floors and ceilings (n = 3) was much smaller, while the plants situated in concrete new buildings (n = 2) were not a source of organic solvents. The calculated effect specific exposure index (EI), assuming an additive effect and based on the effect specific limit values (ESLVs) for two critical effects [irritation mucous membranes and (pre) narcotic effects] exceeded unity in one workroom in two of the screen printing lants. The calculated EIs for the residents of the houses on the first floor, based on the same ESLVs, but adjusted to potential continuous exposure and interindividual differences in susceptibility, did not exceed unity. However, episodes of irritation of mucous membranes and (pre) narcotic effects may occur.     

经排风系统传播SARS可能性的示踪气体实验研究

目的 测定和分析某医院住院部病房楼空气流向及其与排风管道分布的关系并探讨和验证严重急性呼吸综合征(SARS)在医院感染可能的传播途径和影响因素。方法 在某医院住院部SARS输入病例所在病房卫生间燃放植物油熏香(示踪气体);为控制病房卫生间排风扇的开启、顶层抽风机的状态和病房新风系统等主要影响因素,共设计了6种实验状态。由4组实验员分别盲法到各楼层的4、5号病房采集、测量空气样本,并分别按10等分记分法评估其气味浓度。结果 在医院住院部8～13层的各病房均检测到示踪气体,在不同实验状态下,气体弥散的方向和浓度不尽相同。结论 医院目前的建筑结构和通风系统具备了病原体气溶胶自下而上经排风管道垂直传播的通道和空气动力学条件,示踪气体的分布与发病分布有一定的关联性。提示SARS存在气溶胶或其他载体形式长距离传播的可能性和证据,而在现有设施条件下,针对性的预防管理措施可在一定程度上阻断病原体经排风系统的传播。     

Models for retrospective quantification of indoor radon exposure in case-control studies

In epidemiologic studies on lung cancer risk due to indoor radon the quantification of individual radon exposure over a long time period is one of the main issues. Therefore, radon measurements in one or more dwellings, which in total have been inhabited by the participants for a sufficient time-period, are necessary as well as consideration of changes of building characteristics and ventilation habits, which influence radon concentration. Given data on 1-y alpha-track measurements and personal information from 6,000 participants of case-control studies in West and East Germany, an improved method is developed to assess individual radon exposure histories. Times spent in different rooms of the dwelling, which are known from a personal questionnaire, are taken into account. The time spent outside the house (average fraction 45%) varies substantially among the participants. Therefore, assuming a substantially lower radon exposure outside the dwelling, the residence time constitutes an important aspect of total radon exposure. By means of an analysis of variance, important determinants of indoor radon are identified, namely constant conditions such as type of house (one family house or multiple dwelling), type of construction (half-timbered, massive construction, lightweight construction), year of construction, floor and type of basement, and changeable conditions such as heating system, window insulation, and airing habits. A correction of measurements in former dwellings by factors derived from the analysis is applied if current living conditions differ from those of the participants at the time when they were living in the particular dwellings. In rare cases the adjustment for changes leads to a correction of the measurements with a factor of about 1.4, but a reduction of 5% on average only. Exposure assessment can be improved by considering time at home and changes of building and ventilation conditions that affect radon concentration. The major concern that changes in ventilation habits and building conditions lead to substantial errors in exposure (and therefore risk) assessment cannot be confirmed in the data analyzed.