Indoor and outdoor air quality assessment of four wastewater treatment plants

The study assessed the air quality of four wastewater treatment plants (WWTPs) by monitoring levels of hydrogen sulfide (H2S) and endotoxin. Samples were taken over a 1-year period (2001-2002). The unit operations at each WWTP were categorized as: (a) grit removal, (b) primary clarification, (c) biological treatment, (d) secondary clarification, (e) sludge dewatering, and (f) digestion. Temperature and humidity were monitored simultaneously, whereas airborne H2S and endotoxin were monitored at each of the six unit operations in each plant. Carbonaceous biochemical oxygen demand (CBOD) and total incoming flow of the day of visit were also recorded. The geometric means of H2S concentration were less than 1 ppm and endotoxin ranged from 6-1247 EU/m3. A mixed model analysis of covariance (ANCOVA) was used for the statistical analysis. While temperature was not associated with the levels of both contaminants, humidity was influential on the level of H2S (p < 0.01) but not of endotoxin. CBOD did not affect the levels of either contaminant; however, incoming flows showed an association with the levels of H2S (p < 0.05). The concentrations of H2S in the six unit operations were statistically different, whereas endotoxin did not show any differences in concentrations between units. Individual comparisons proved that concentrations of H2S in the grit removal and sludge dewatering unit operations were statistically higher than the other operations. Overall, the concentrations of H2S varied depending on total incoming flow, humidity, and different unit operations. This trend was not observed for endotoxin. The results showed that the factors analyzed affected concentrations of H2S and endotoxin differently. Therefore, different control methods for endotoxin and H2S need to be considered to effectively reduce their concentrations at WWTPs.     

荆门市室内空气质量监测分析

为了解2005~2006年荆门市城区生活和办公室内的空气质量状况,按照相关国家标准,对居室内和办公室内近两年的空气质量进行了调查,将结果分析如下。1材料与方法1.1监测对象2005~2006年选择荆门市城区117家未装修及不同程度装修的家居及办公室,检测室内空气,并进行比较。1.2监测项目甲醛、氨、二氧化碳、细菌总数、温度、相对湿度。1.3空气样品的采集根据室内面积大小及现场情况确定采样点,小于50m2的房间设检测点1个,50~100m2设3个,100m2以上设点5个,呈对角线或梅花式分布,共设采样点1134个。采样前关闭门窗12小时,记录采样点的温度和相对湿度…     

Indoor air quality of schools in Alexandria City

Poor air quality in schools can affect children's desire and ability to concentrate and learn and may lead to increased rate of absenteeism. This study was carried out with the aim of characterizing and measuring indoor air quality in school buildings, measuring ventilation status and studying the impact of design and environmental parameters on some measured pollutant levels. The study was carried out in some primary schools of Alexandria City. All ventilation rate levels exceeded the ASHRAE standard of 15 cfm/pupil except for a few cases. Badly located and small window area led to air stagnation and low ventilation rates. Levels of TSP greatly exceeded a suggested daily guideline of 150 microg/m3. The highest average levels of TSP were found inside classrooms surrounded by unpaved playground and located near semi rural, commercial and heavy traffic areas, while lowest levels were in classrooms located next to residential areas. The average total bacteria were highest in winter. There was also a slight increase in respiratory symptoms and signs in winter. There was a significant positive correlation between average total, pathogenic and non-pathogenic bacteria with average TSP levels, indoor CO2 levels and relative humidity while a significant negative correlation was observed with ventilation rate and class volume occupied. The average attack rate of respiratory conditions was 1.96 episode per child. Running nose was the highest frequent symptom. Students of first grade, had an incidence rate higher than that among fifth grade students.     

打印复印设备释放污染物与健康效应

  目的   探究打印机释放颗粒物浓度的时空分布及通风因素的影响。  方法  在体积为0.606 m³（1.035 m × 0.711 m × 0.823 m）实验仓中进行实验,使用气溶胶粒径谱仪监测实验仓内不同位置的颗粒物浓度随打印机工作时间的变化;探究通风时机、通风流量和通风时长对颗粒物浓度的影响。  结果  实验仓内不同位置的颗粒物数量浓度达到峰值的时间无差异;颗粒物浓度峰值随高度升高而降低 （r_s = – 0.740,P < 0.001）,且随水平距离增加而衰减（r_s = – 0.351,P < 0.01）。在打印前、打印开始、打印结束后通风和不通风时颗粒物浓度峰值分别为（– 26.96 ± 8.42）、（– 5.67 ± 4.72）、（39.23 ± 16.85）和（75.43 ± 15.37） p/cm³,有统计学差异（P < 0.05）。在打印开始时通风,颗粒物数量浓度峰值随通风流量增加和通风时间延长而显著下降。  结论  打印机释放颗粒物在实验仓内扩散迅速,浓度峰值呈现垂直分布和距离衰减;通风时机、通风流量和通风时长可影响浓度水平。     

Towards an improved air quality index

Air quality indices (AQI) are commonly used to indicate the level of severity of air pollution to the public. A number of methods were developed in the past by various researchers/environmental agencies for the calculation of AQI, but there is no universally accepted method, appropriate for all situations. An updated review of the major air quality indices developed worldwide is presented in this paper. These methods differentiate mainly in the number of pollutants included, its sampling period and air quality classes and breakpoints. When applying different AQI to a common case study, important differences are found in terms of the classification of the quality of the air. The purposes of this research are to identify weaknesses of the current AQI and to discuss possible changes and updates with Portugal as case study. A survey, with 10 questions about the calculation and use of the AQI and its dissemination to public, was delivered to the five regional environmental agencies in Portugal and, based on results, modifications to the current AQI are proposed. Two main changes—inclusion of PM2.5 and specific urban/industrial AQI—were tested, comparing the current and the proposed AQI along the 2014 year. It is observed that a significant difference exists when specific urban and industrial sites are considered when calculating the AQI. On the other hand, and contrarily to other regional studies, the results show that the inclusion of fine suspended particulate (PM2.5) does not impact the final AQI value.     

Indoor air quality assessment of daycare facilities with carbon dioxide,temperature, and humidity as indicators

Poor indoor air quality (IAQ) in daycare facilities affects both attending children and care providers. Incident rates of upper-respiratory-tract infections have been reported to be higher in children who attend daycare. Excessive carbon dioxide (CO2) exposure can cause several health effects and even sudden infant death. For this study, 26 facilities were randomly selected in a Midwestern county of the United States. CO2, room temperature, and relative humidity were used as indicators for IAQ and comfort levels. These IAQ parameters were continuously monitored for eight hours at each facility by a direct-reading instrument that was calibrated before each measurement. More than 50 percent of the facilities had an average CO2 level over the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) standard of 1,000 parts per million (ppm). For temperature and relative humidity, respectively, 42.3 percent and 15.4 percent of facilities were outside of the ASHRAE-recommended comfort zones. The nap-time average CO2 level was about 117 ppm higher than the non-nap-time level. The increment of the nap-time CO2 level in the sleeping-only room over the level in multipurpose rooms was statistically significant (p < .05). According to stepwise multiple regression analysis, nap-time CO2 level was predicted by CO2 level before occupancy, nap-time average temperature, carbon monoxide, and child density (R2 = .83). It is recommended that an appropriate IAQ standard for daycare facilities be established and that children should not be placed in a completely isolated room during nap time.     

Indoor air quality in ice skating rinks in Hong Kong

Indoor air quality in ice skating rinks has become a public concern due to the use of propane- or gasoline-powered ice resurfacers and edgers. In this study, the indoor air quality in three ice rinks with different volumes and resurfacer power sources (propane and gasoline) was monitored during usual operating hours. The measurements included continuous recording of carbon monoxide (CO), carbon dioxide (CO(2)), total volatile organic compounds (TVOC), particulate matter with a diameter less than 2.5 microm (PM(2.5)), particulate matter with diameter less than 10 microm (PM(10)), nitric oxide (NO), nitrogen dioxide (NO(2)), nitrogen oxide (NO(x)), and sulfur dioxide (SO(2)). The average CO, CO(2), and TVOC concentrations ranged from 3190 to 6749 microg/m(3), 851 to 1329 ppm, and 550 to 765 microg/m(3), respectively. The average NO and NO(2) concentrations ranged from 69 to 1006 microg/m(3) and 58 to 242 microg/m(3), respectively. The highest CO and TVOC levels were observed in the ice rink which a gasoline-fueled resurfacer was used. The highest NO and NO(2) levels were recorded in the ice rink with propane-fueled ice resurfacers. The air quality parameters of PM(2.5), PM(10), and SO(2) were fully acceptable in these ice rinks according to HKIAQO standards. Overall, ice resurfacers with combustion engines cause indoor air pollution in ice rinks in Hong Kong. This conclusion is similar to those of previous studies in Europe and North America.     

Indoor air quality and occupational exposures at a bus terminal

This article presents an assessment of indoor air quality at a bus terminal. For this purpose, field surveys were conducted, and air samples were collected and analyzed for the presence of selected indoor air quality indicators. Mathematical modeling was performed to simulate bus emission rates, occupational exposure, and ventilation requirements to maintain acceptable indoor air quality. A sensitivity analysis based on literature-derived emission rates estimates was conducted to evaluate the effect of seasonal temperature changes within the terminal. Control measures to improve indoor air quality at the terminal are also outlined. While carbon monoxide concentrations were below the corresponding American Conference of Governmental Industrial Hygienists' (ACGIH) standards under normal operating conditions, they exceeded the 8-hr recommended average standard at peak hours and the World Health Organization (WHO) standard at all times. Total suspended particulates levels, on the other hand, were above the 24-hr American Society of Heating, Refrigerating and Air Conditioning Engineers' (ASHRAE) standard. Carbon monoxide emission rates that were estimated using the transient mass balance model correlated relatively well with those reported in the literature. Modeling results showed that the natural ventilation rate should be at least doubled for acceptable indoor air quality. While pollutant exposure levels depended on the individual activity patterns and the pollutant concentration, pollutant emissions rates within the terminal were affected mostly by the temperature with a 20-25 percent variation in carbon monoxide levels due to changes in seasonal temperatures.     

Indoor air pollutant exposure and determinant factors controlling household air quality for elderly people in Hong Kong

This study investigated the levels and determinant factors of indoor air pollutants including fine particles (PM_2.5), nitrogen dioxide (NO₂), and formaldehyde (HCHO) in 55 households exclusively for the elderly in Hong Kong during summer and winter (Jul.–Sep. 2016 and Nov. 2016–Mar. 2017). The average concentrations of PM_2.5, NO₂, and formaldehyde were 25.3?±?15.0, 40.5?±?16.0, and 26.1?±?22.8 μg/m³ in summer and 34.2?±?19.0, 43.5?±?17.0, and 15.4?±?4.5 μg/m³ in winter, respectively. There were ~?50.3% of households exceeding the World Health Organization indoor air quality standard for PM_2.5 throughout the study, with ~?40.6 and ~61.0% of the households in summer and winter, respectively. The determinant factors for indoor PM_2.5 and NO₂ concentrations were identified as from incense burning and cooking. Cooking with suitable ventilation is an important factor to ease indoor pollutant concentrations. Both of PM_2.5 and NO₂ indoor concentrations showed good correlations with outdoor concentrations. Winter was observed with higher pollutant concentrations than summer except for formaldehyde concentrations. Major factors controlling indoor formaldehyde concentrations are temperature and humidity. The outcome will be useful for the development of future indoor air quality guidelines for Hong Kong.     

Indoor air guide values for phenol

The German Working Group on Indoor Guidelines of the Federal Environment Agency and the States′ Health Authorities is issuing indoor air guide values to protect public health. For health evaluation of phenol in indoor air a qualified working-place study emphasizing the POD hemo- and hepatotoxicity as well as results of a limited inhalation-study which underline neurological effects on rats were used. The Working Group assessed a lowest observed adverse effect level of 21 mg Phenol/m3 in the working-place study and 100 mg Phenol/m3 in the animal-based study. Both toxicological derivatives come to the same result but the working-place study was preferred. By applying a factor of 10 for interindividual variability, a factor of 4.2 for the different exposing-time of workers and usual population and a modifying factor of 2 regarding children a health hazard guide value (RW II) of 0.2 mg phenol/m3 is obtained. A health precaution guide value of 0.02 mg phenol/m3 is recommended.     

Indoor air quality in restaurants with and without designated smoking rooms

Indoor air quality in restaurants was studied in two cities in northwest Ohio after clean indoor air ordinances had been enacted. Carbon dioxide and ultrafine particles were measured in two restaurants in Toledo and two restaurants in Bowling Green. One restaurant in each city was smoke free, and one restaurant in each city contained a dedicated smoking room. A smoke free office space was also assessed as a reference site. Measurements were collected with datalogging instrumentation simultaneously in both the designated smoking room, if present, and in the nonsmoking section. For smoke free establishments, datalogging instrumentation was also used. Carbon dioxide levels were elevated in all four restaurants, with only 32% of the measurements meeting the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) criterion level of 1000 ppm. Ultrafine particles currently do not have any formal standard or guideline. Statistically significant differences were evident between all four restaurants and the reference site. The largest differences were found between the two designated smoking rooms and the reference site (p < 0.001), with the mean levels in the smoking rooms up to 43 times higher than in the reference site. The results from this study indicate inadequate fresh air supply in all four restaurants, particularly in the designated smoking rooms, and the possibility that the designated smoking rooms were not containing the environment tobacco smoke, based on the ultrafine particle concentrations measured in the nonsmoking areas of the smoking restaurants.     

Indoor air quality and health problems associated with damp floor coverings

Objectives To study the relationship between a high incidence of bronchial asthma among employees working in an office building and an indoor air problem related to the degradation of polyvinyl chloride (PVC) floor coverings in the building. The indoor air measurements and results of renovations are also described.Methods Employees symptoms were surveyed by a questionnaire, and the incidence of asthma was calculated from the medical records for 1997–2000. The quality of indoor air was assessed by microbial sampling and by investigation of the building for possible moisture damage. Indoor air was sampled for volatile organic compounds (VOCs) through Tenax adsorbent tubes. In situ volatile emission measurements from the concrete floor were performed via the field and laboratory emission cell (FLEC) method.Results In an office with approximately 150 employees, eight new cases of asthma were found in 4 years. In addition, the workers complained of respiratory, conjunctival and nasal symptoms. Emissions indicating the degradation of plastic floor coverings (e.g. 2-ethyl-1-hexanol, 1-butanol) were found in the indoor air and floor material samples. The plastic floor coverings, adhesives and the levelling layers were carefully removed from 12 rooms. The VOCs had diffused into the underlying concrete slabs. The concrete was warmed to remove the diffused VOCs from these areas. After the repairs the concentrations of the VOCs indicating the degradation of PVC, decreased, as did the prevalence of the employees symptoms and several asthma patients need for medication.Conclusions The workers in the office building complained of several respiratory, conjunctival and dermal symptoms. The incidence of adult-onset asthma was approximately nine-times higher than that among Finns employed in similar work. The most probable single cause of the indoor air problem was the degradation of the plastic floor coverings.     

Indoor air pollution and pulmonary performance: investigating errors in exposure assessment

We use pulmonary function measurements on pre-adolescent children and indoor air pollution measurements in the homes of these children to illustrate estimation techniques for linear regression models containing independent variables measured with error. In our data set, replicate measures of indoor air pollutant concentrations provide one method of estimating measurement error variances. Surrogate information in the form of cigarettes smoked is also available for the pollutant of interest. Several estimation procedures are presented, and we combine two estimators, one based on surrogate information and one based on replication information, using generalized least squares.