Humidification and perceived indoor air quality in the office environment.

OBJECTIVE: To evaluate the effect of humidification on the odour, acceptability, and stuffiness of indoor air. METHODS: In a six period cross over trial at the Pasila Office Center, Helsinki, the air of two wings of the building in turn were ventilated with air of 30%-40% humidity. A third wing served as a non-humidified control area. The quality of indoor air was assessed weekly by a panel containing 18 to 23 members. The intraindividual differences in the ratings for odour, stuffiness, and acceptability between humidified and non-humidified wings were used to assess the effect of humidification. The roles of sex, current smoking, and age as potential effect modifiers were assessed by comparing the mean intraindividual differences in ratings between the groups. RESULTS: Humidified air was found to be more odorous and stuffy (paired t test P = 0.0001) and less acceptable than the non-humidified air (McNemar's test P < 0.001). The differences in odour and stuffiness between humidified and non-humidified air were greater for women and for non-smokers, and greatest differences were in the youngest age group, and least in the oldest age group. The differences were not significant. CONCLUSIONS: An untrained panel of 20 members is able to differentiate a slight malodour and stuffiness in indoor air. The results suggest that steam air humidification decreases the perceived air quality. This effect is strongest in women and young subjects.     

Microbiological quality of hospital indoor air. Determinant factors for microbial concentration in air of operating theatres

Foregoing research presents results of total number of bacteria and fungi assays carried out in air of operating theatres before, during and directly after planned surgical procedure. Basing on the results obtained in winter and summer the assessment of bacteria and fungi concentration in atmospheric air impact on microbial quality of air inside of operating theatre was elaborated. Investigation of the reason of high concentration of bacteria in air inside of operating rooms was conducted simultaneously. Presented results of microbial air purity collected from atmospheric air in parallel with indoor air demonstrated that air filters applied in air-conditioning system worked correctly and bacterial contamination of air had different reasons.     

Effect of indoor air quality in the postnatal period on lung function in pre-adolescent children: a retrospective cohort study in Poland

The purpose of this study was to determine the association between level of lung function in pre-adolescence and indoor air quality in the postnatal period. The retrospective cohort study was carried out in a sample of 1036 pre-adolescent children (9 years of age) attending schools in two residential areas of Krakow, Poland. Measurement of health outcomes considered lung function together with height and weight. Indoor air quality was based on environmental tobacco smoke and type of household heating. In addition, the number of winter months that occurred during the first 6 months of life was included as a key independent variable. Multivariate linear regression of lung function measured by forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC), and postnatal exposure to indoor pollution in the heating season (PEIP score) was adjusted for potential confounders such as maternal smoking during pregnancy and parental education as a proxy of social class. In the total study sample, the adjusted beta coefficient for FEV1 per unit of the PEIP score was -0.06 (P=0.02), while that for FVC was -0.05 (P=0.04). The analysis carried out in the more polluted area found that children living in households heated with gas or coal had a PEIP score that was strongly inversely related to lung function (adjusted beta coefficient for FEV1=-0.13; P=0.03; for FVC=-0.15, P=0.01), whereas regression coefficients were not significant in the group of children living in households with central heating. This study suggests that a lower level of lung function in pre-adolescent children can be related to postnatal exposure to indoor emissions in the winter.     

Effect of air humidification on the sick building syndrome and perceived indoor air quality in hospitals: a four month longitudinal study.

The sensation of dryness and irritation is essential in the sick building syndrome (SBS), and such symptoms are common in both office and hospital employees. In Scandinavia, the indoor relative humidity in well ventilated buildings is usually in the range 10-35% in winter. The aim of this study was to evaluate the effect of steam air humidification on SBS and perceived air quality during the heating season. The study base consisted of a dynamic population of 104 hospital employees, working in four new and well ventilated geriatric hospital units in southern Sweden. Air humidification raised the relative air humidity to 40-45% in two units during a four months period, whereas the other two units served as controls with relative humidity from 25-35%. Symptoms and perceived indoor air quality were measured before and after the study period by a standardised self administered questionnaire. The technical measurements comprised room temperature, air humidity, static electricity, exhaust air flow, aerosols, microorganisms, and volatile organic compounds in the air. The most pronounced effect of the humidification was a significant decrease of the sensation of air dryness, static electricity, and airway symptoms. After four months of air humidification during the heating season, 24% reported a weekly sensation of dryness in humidified units, compared with 73% in controls. No significant changes in symptoms of SBS or perceived air quality over time were found in the control group. The room temperature in all units was between 21-23 degrees C, and no significant effect of air humidification on the air concentration of aerosols or volatile organic compounds was found. No growth of microorganisms was found in the supply air ducts, and no legionella bacteria were found in the supply water of the humidifier. Air humidification, however, significantly reduced the measured personal exposure to static electricity. It is concluded that air humidification during the heating season in colder climates can decrease symptoms of SBS and perception of dry air.     

The effect of air humidification on symptoms and perception of indoor air quality in office workers: a six-period cross-over trial.

The objective of this study was to evaluate the effect of air humidification on (a) the dryness of the skin and mucosa, (b) allergic and asthmatic reactions, and (c) the perception of indoor air quality. A total of 290 office workers at the Pasila Office Center were included in a six-period cross-over trial. One wing of the building was operated with 30-40% humidification, and the other wing operated under conditions of no air humidification (relative humidity from natural conditions was 20-30%). The length of each study period was 1 work wk. The workers were instructed to keep a structured daily diary of their symptoms, their perception of the indoor air, and potential determinants of the symptoms. A total of 211 (72.6%) workers who returned at least two weekly diaries, and who had experienced both humidified and nonhumidified conditions, were included in the analyses. The primary outcome--dryness symptom score--was characterized by dryness, irritation or itching of the skin and eyes, dryness or irritation of the throat, and nasal dryness. Means of the daily symptom scores and perception ratings during the humidified and nonhumidified periods were calculated for each participant, and intraindividual differences in the means were used to assess the effect of air humidification. The dryness symptom score was significantly smaller during the humidified phase than during the reference phase (paired t test; p less than .05). Allergic symptoms that were considered as a separate outcome, a sensation of dryness, and draft were also significantly less frequent during the humidification phase (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Indoor air particles in office buildings with suspected indoor air problems in the Helsinki area

Objectives

Airborne particle concentrations can be used as quality indicators of indoor environments. The previous lack of reference data has limited the use of particle measurements in office environments. The aim of this study was to describe the concentrations of airborne particles (≥ 0.5 μm and ≥ 5.0 μm) in 122 Finnish office buildings with suspected indoor air problems.

Materials and Methods

The database consisted of indoor air and supply air particle samples collected in 2001–2006 from the Helsinki area. The particle concentrations (≥ 0.5 μm and ≥ 5.0 μm) were measured in the indoor air (528 samples from 122 office rooms) and in the supply air (384 samples from 105 office rooms) with an optical particle counter. Airborne particle concentrations ≥ 0.5 μm were categorized according to the efficiency of supply air filtration and health survey data.

Results

The mean concentrations in the indoor air equaled 1900 particles/l and in the supply air 1300 particles/l. The efficiency of supply air filtration decreased the fine particles counts in both the indoor and supply air. The counts of large particles, ≥ 5.0 μm, were low in the indoor air. Airborne counts of ≥ 0.5 μm particles (geometric mean) were statistically higher in the offices whose occupants had work-related symptoms (eye and/or upper respiratory symptoms or upper respiratory infections) than in the offices whose occupants had no such symptoms. However, the symptoms may also be linked to other indoor air problems or particle characteristics not studied in this work.

Conclusions

This study indicates typical airborne particle levels (≥ 0.5 μm and ≥ 5.0 μm) in Finnish office buildings with suspected indoor air problems. The results can be used to evaluate the quality of indoor environment, possible indoor air problems, and the need for additional investigations.     

Effect of building frame and moisture damage on microbiological indoor air quality in school buildings

The effect of building frame and moisture damage on microbial indoor air quality was characterized in 17 wooden and 15 concrete or brick school buildings. Technical investigations to detect visible moisture and mold damage were performed according to a standardized protocol. Viable airborne microbes were determined by using a six-stage impactor (Andersen 10-800). Mean concentrations of viable airborne fungi were significantly higher in wooden schools than in concrete schools, showing that the frame material was a determinant of concentrations of airborne fungi. Moisture damage of the building did not alter the fungal concentrations in wooden school buildings. In contrast, in concrete schools the effect of moisture damage was clearly seen as higher concentrations compared with the reference schools. Aspergillus versicolor, Stachybotrys, and Acremonium were detected only in samples from moisture damaged buildings, and can be considered marker fungi of such damage in school buildings. In addition, the presence of Oidiodendron as well as elevated concentrations of Cladosporium and actinobacteria were associated with moisture damage in concrete schools.     

Clearing the air: a model for investigating indoor air quality in Texas schools

This pilot project focused on the assessment of indoor air quality at a local high school in Galveston, Texas, using methods based on guidelines for the U.S. Environmental Protection Agency's Indoor Air Quality Tools for Schools program. Tools for Schools, developed for evaluating and ensuring acceptable air quality for schools, takes a low-cost, minimal-involvement, primarily educational approach. The authors also compared the findings from this approach with the results of an air-sampling program. The overall goal was to determine if use of Tools for Schools was sufficient to identify conditions with the potential to cause adverse health effects. The primary objectives were to 1) establish an indoor air quality committee for the school to implement Tools for Schools assessments and management strategies, 2) collect air quality data in high-risk areas identified within the school by the indoor air quality committee, 3) collect outdoor air quality data at or in close proximity to the school, and 4) develop methods and instruments for assessing environmental risks associated with daily school attendance. Data were gathered on levels of formaldehyde and other volatile organic compounds (VOCs), ozone, particulate matter (PM10), mold, relative humidity, and temperature. Data values for each sampled pollutant were compared with federal standards, recommended values established by the American Conference of Governmental Industrial Hygienists for non-industrial populations, and effects screening levels developed by the Texas Commission on Environmental Quality. Levels of all VOCs except formaldehyde were found to be well within guidelines, as were ozone and particulate-matter levels. Mold, however, was widespread, including both common species and species associated with allergy and asthma, such as Aspergillus and Alternaria. In general, Tools for Schools provides an excellent foundation for a school indoor air quality program, although the authors did find it necessary to streamline data collection and did find that mold with the potential for adverse health effects was present, albeit not visible in some areas.     

A two-year study of microbiological indoor air quality in a new apartment

Concentrations and types of bacteria and fungi in the air and on surfaces were measured in a new, one-bedroom apartment before occupancy and at 3-mo intervals thereafter for 2 y. Air samples were collected with a single-stage impactor at two locations in the kitchen, living room, bedroom, bathroom, and outdoors. Even though damp surfaces supported large populations of bacteria and yeasts, the air concentrations in the kitchen and bathroom were similar to those in other rooms. No changes in concentrations or types of microbiological contamination were observed between the first and second years of occupancy, but elevated outdoor humidity, lower air temperature, and winds from the northeast were associated with higher bacterial and fungal air concentrations. The median air concentrations of bacteria were 98 cfu/m3 (95% confidence interval 26-372 cfu/m3) indoors and 101 cfu/m3 (28-364 cfu/m3) outdoors. The median air concentrations of fungi were 198 cfu/m3 (58-673 cfu/m3) indoors and 362 cfu/m3 (113-1158 cfu/m3) outdoors. This information established useful baseline data against which measurements in neighboring complaint residences could be compared.     

An international survey of indoor air quality,ventilation, and smoking activity in restaurants: a pilot study

During a pilot study of indoor air quality in restaurants, a survey was performed in 34 medium-priced restaurants in six countries in Asia, Europe, and North America using a uniform protocol. The concentration of selected constituents of environmental tobacco smoke (ETS) present in occupied areas was determined during lunch and dinner periods by measuring the levels of four particulate-phase markers and two gas-phase markers. The particulate-phase markers determined were respirable suspended particles, ultraviolet particulate matter, fluorescing particulate matter, and solanesol particulate matter. The gas-phase markers were nicotine and 3-ethenylpyridine (3-EP). Correlation between the markers was investigated to explore an improved monitoring approach. It was concluded that at least one marker in each phase was necessary to describe adequately the ETS load. An assessment was made of the ventilation system in each restaurant, and effective ventilation rates were determined based on CO(2) measurements. Smoking activity was also monitored. These data were used to model nicotine and 3-EP concentrations that resulted in a satisfactory prediction of their levels, especially at the higher concentrations. A total number of 1370 questionnaires were returned by the restaurant patrons in five countries. In some countries, dissatisfaction rates above 20% were observed for draft, freshness of air, and noise. The dissatisfaction rates related to tobacco smoke were less than 20%, which is lower than would be predicted based on measured ETS levels. Based on the results of this international pilot study, recommendations are given for future studies of this type.     

Effectiveness of the maintenance operations on the air conditioning systems of a university building in relation to the microbiological quality of the air indoor

The microbiological quality of the air indoor is influenced from various factors and one of the most important is represented from the maintenance of the conditioning systems. In this study it has been estimated the effectiveness of an intervention of cleaning and maintenance on the systems of conditioning of an university building executing sampling before and after such intervention. The two results were confronted and it is observed as the maintenance of the air conditioners has influenced on the quality of the air indoor.     

Assessment of the indoor air quality in copy centres at Aveiro,Portugal

This study presents continuous measurements of size-segregated particulate matter, total volatile organic compounds, ozone, formaldehyde, comfort parameters (temperature and relative humidity), CO and CO₂ at two copy centres (A and B) in Aveiro, Portugal. PM₁₀ samples collected with low-volume samplers were used to determine the carbonaceous content (organic and elemental carbon) by a thermo-optical technique. Mean PM₁₀ levels of 55.8?±?7.50 μg m^?3 and 51.3?±?9.35 μg m^?3 were obtained in copy centres A and B, respectively. The 24-h indoor PM₁₀ concentration at both copy centres exceeded the protection limit established by the Portuguese legislation. Around 60 % of the PM₁₀ were composed of particles with sizes below 2.5 μm. On average, organic carbon accounted for 27.6 % (copy centre A) and 18.6 % (copy centre B) of the PM₁₀ mass indoors, whereas a lower mass fraction of 11.5 % was found for both outdoor spaces. The much higher indoor levels of organic carbon suggest significant contribution by indoor sources. The ozone level increased in both copy centres when the photocopiers started to work. Mean ozone levels (0.055?±?0.005 and 0.048?±?0.006 ppm in copy centres A and B, respectively) during business hours may exceed the standard recommended for workplaces (0.05 ppm), representing a cause of possible adverse health effects on employees. The indoor-to-outdoor ozone concentration ratios were greater than 1 in both centres, indicating an important contribution of indoor sources. Formaldehyde levels remained always below the World Health Organisation guideline for indoor air (0.1 mg m^?3). Total concentrations of volatile organic compounds were also relatively low, in general ranging from around 190 to 300 ppb. The indoor-to-outdoor concentration ratios were in the range between 0.70 and 0.76. Results showed that operation of laser printers can lead to high particulate matter and ozone concentration indoors. Pollutants associated with printing equipment have potential to cause adverse health effects if exposures are sufficiently high. Precautions should be taken to minimise the risks of exposed workers.     

客房内空气品质调查

目的 了解广州市宾馆客房的室内空气污染状况。方法 采用SPSS12．0进行数据分析和空气质量综合指数法进行综合评价。结果 客房内物理性参数夏季大部分在合格范围内,冬季温度和相对湿度有部分超过标准;客房内的空气属于未污染,各参数实测的平均浓度均在室内空气质量标准所规定的范围之内,各参数指数在0．27-0．63,超标率较低。结论 客房应加强通风除湿,空气质量综合指数法简捷适用,值得推广。     

Evaluation of indoor air quality using the decibel concept

Weber-Fechner's law concerning the perception of sound by man with time expressed as a logarithmic function can also be used for the odour constituent used in the evaluation of indoor air quality in buildings. A new unit dB (odour) based on the concentration of Total Volatile Organic Compounds (TVOC) is proposed as it is currently the basis for determining the air change rate. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to 1 and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and a threshold concentration (TVOC) of 50 mug/m3 to 0 dB (odour). The upper limit is determined by the initial value of toxicity TVOC - 25 000 mug/m3 to 135 dB (odour). Optimal values correspond to PD = 20% (according to EUR 14449 EN) and allowable values correspond to PD = 30% (see Table 3) are proposed; therefore the same values used to evaluate noise can be used to evaluate air quality and additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The determination of the required volume of fresh air for ventilation and air-conditioning systems according to the new principles is the subject of the second part of this paper.     

Microbiological quality of the air in "small gastronomy point"

The aim of this work was the estimation of microbial contamination of the air in "small gastronomy point". The study included three places, which have been separated on the ground of their function: 1. area of subsidiaries, 2. area of distribution (sale and serving meal), 3. area of consumption. The total numbers of aerobic mesophilic bacteria, yeasts and moulds were determined by sedimentation method. Taxonomy units of fungal aerosol were also estimated. The samples of air were collected in 16 investigation points in the morning (8-8.30) and in the afternoon (14-14.30). Four series of measurements were carried out and in general 128 of air samples were tested. The results showed that numbers of bacteria, yeasts and moulds were variable and received respectively 30-3397, 0-254 and 0-138 cfu x m(-3). Microbial contamination of air changed depending on area character (the highest average count of bacteria occurred in the air of consumption area and fungi in subsidiaries area), time of a day (contamination of the air increased in the afternoon) and determination date. Only in single samples the numbers of bacteria and fungi were higher than recommended level. Pigmentary bacteria had high participation in total count of bacteria and filamentous fungi were represented mostly by Penicillium sp. and Cladosporium sp.     

Influence of indoor climate on the sick building syndrome in an office environment. The Danish Indoor Climate Study Group

The influence of indoor climate factors on symptoms of the sick building syndrome was investigated in Greater Copenhagen, Denmark. Altogether, 2369 office workers in 14 buildings, where indoor climate measurements were made, filled out a questionnaire. Multivariate logistic regression analyses of the multifactorial effects on the prevalence of work-related mucosal irritation and work-related general symptoms among the office workers showed that the concentration of macromolecular organic floor dust, the floor covering, the number of workplaces in the office, the age of the building, the type of ventilation, and two easily recognizable factors, the shelf factor and the fleece factor, were associated with the prevalence of symptoms.     

Indoor air quality in urban and rural kindergartens: short-term studies in Silesia,Poland

More than 80% of people living in urban areas who monitor air pollution are exposed to air quality levels that exceed limits defined by the World Health Organization (WHO). Although all regions of the world are affected, populations in low-income cities are the most impacted. According to average annual levels of fine particulate matter (PM2.5, ambient particles with aerodynamic diameter of 2.5 μm or less) presented in the urban air quality database issued by WHO in 2016, as many as 33 Polish cities are among the 50 most polluted cities in the European Union (EU), with Silesian cities topping the list. The aim of this study was to characterize the indoor air quality in Silesian kindergartens based on the concentrations of gaseous compounds (SO₂, NO₂), PM2.5, and the sum of 15 PM2.5-bound polycyclic aromatic hydrocarbons (PAHs), including PM2.5-bound benzo(a)pyrene (BaP), as well as the mutagenic activity of PM2.5 organic extracts in Salmonella assay (strains: TA98, YG1024). The assessment of the indoor air quality was performed taking into consideration the pollution of the atmospheric air (outdoor). I/O ratios (indoor/outdoor concentration) for each investigated parameter were also calculated. Twenty-four-hour samples of PM2.5, SO₂, and NO₂ were collected during spring in two sites in southern Poland (Silesia), representing urban and rural areas. Indoor samples were taken in naturally ventilated kindergartens. At the same time, in the vicinity of the kindergarten buildings, the collection of outdoor samples of PM2.5, SO₂, and NO₂ was carried out. The content of BaP and the sum of 15 studied PAHs was determined in each 24-h sample of PM2.5 (indoor and outdoor). In the urban site, statistically lower concentrations of SO₂ and NO₂ were detected indoors compared to outdoors, whereas in the rural site, such a relationship was observed only for NO₂. No statistically significant differences in the concentrations of PM2.5, PM2.5-bound BaP, and Σ15 PAHs in kindergartens (indoor) versus atmospheric (outdoor) air in the two studied areas were identified. Mutagenic effect of indoor PM2.5 samples was twice as low as in outdoor samples. The I/O ratios indicated that all studied air pollutants in the urban kindergarten originated from the ambient air. In the rural site concentrations of SO₂, PM2.5 and BaP in the kindergarten were influenced by internal sources (gas and coal stoves).