Characteristics of indoor and outdoor airborne fungi at suburban and urban homes in two seasons

Literature has suggested association between damp environments, microbial exposure, and higher prevalence of respiratory symptoms and diseases. The study began by evaluating the airborne fungal concentrations at urban and suburban areas of a typical metropolitan city in southern Taiwan for the estimation of related health risks. A group of representative homes, based on the housing characteristics questionnaires completed earlier, were selected from two parts of the city; urban and suburban. Burkard sampler (BURKARD, Rickmansworth, England) was used to collect airborne fungi onto agar plates with malt-extract. After incubation and identification, concentrations of airborne fungi were calculated as CFU/m3. The geometric mean (GM) concentration for indoors was 8946 (4372-18,306) CFU/m3 in winter and 4381 (1605-11,956) in summer. For outdoors, it was 11,464 (5767-22,788) CFU/m3 in winter and 4689 (1895-11,603) in summer. In summer, the total fungal concentration, both indoors and outdoors of suburban homes, were significantly higher than those of urban homes. The dominant fungi contributing to such a difference were indoor Cladosporium spp. and outdoor Penicillium spp. (P < 0.01). The indoor/outdoor ratio (I/O) was similar in two areas except for Penicillium spp. in winter and Aspergillus spp. in summer; both higher in the suburban area. Significantly higher levels of airborne fungi were observed in this region than those seen in northern Taiwan or other parts of the world. Future investigations are needed to further examine the effects of these exposures on the related health problems.     

Relationship between indoor and outdoor bio-aerosols collected with a button inhalable aerosol sampler in urban homes

This field study investigated the relationship between indoor and outdoor concentrations of airborne actinomycetes, fungal spores, and pollen. Air samples were collected for 24 h with a button inhalable aerosol sampler inside and outside of six single-family homes located in the Cincinnati area (overall, 15 pairs of samples were taken in each home). The measurements were conducted during three seasons - spring and fall 2004, and winter 2005. The concentration of culturable actinomycetes was mostly below the detection limit. The median indoor/outdoor ratio (I/O) for actinomycetes was the highest: 2.857. The indoor of fungal and pollen concentrations followed the outdoor concentrations while indoor levels were mostly lower than the outdoor ones. The I/O ratio of total fungal spores (median=0.345) in six homes was greater than that of pollen grains (median=0.025). The low I/O ratios obtained for pollen during the peak ambient pollination season (spring) suggest that only a small fraction penetrated from outdoor to indoor environment. This is attributed to the larger size of pollen grains. Higher indoor concentration levels and variability in the I/O ratio observed for airborne fungi may be associated with indoor sources and/or higher outdoor-to-indoor penetration of fungal spores compared to pollen grains. Practical Implication This study addresses the relationship between indoor and outdoor concentrations of three different types of bio-aerosols, namely actinomycetes, fungal spores, and pollen grains. The results show that actinomycetes are rare in indoor and outdoor air in Midwest, USA. Exposure to pollen occurs mainly in the outdoor air even during peak pollen season. Unexpectedly high fungal spore concentrations were measured outdoors during winter. The presented pilot database on the inhalable levels of indoor and outdoor bio-aerosols can help apportion and better characterize the inhalation exposure to these bio-aerosols. Furthermore, the data can be incorporated into existing models to quantify the penetration of biological particles into indoor environments from outdoors.     

建筑室内外空气真菌浓度相关性案例测试分析

选取某高校学生办公室进行室内外空气真菌浓度相关性和粒径的研究。结果表明:室内空气真菌浓度变化范围为1698~4429 cfu/m³,最大值出现在12:00;室外浓度范围为3569~29452 cfu/m³,最大值也出现在12:00。室内外空气真菌浓度比值均小于1,Spearman相关性分析显示室内外空气真菌呈显著正相关,且线性回归分析表明室外空气真菌是室内空气真菌的显著影响因子,可推断本研究的室外空气真菌是室内的主要来源。室内空气真菌浓度与室内人数呈显著正相关。室内外空气真菌均从Ⅰ级到Ⅳ级逐渐增加,而后Ⅴ级到Ⅵ级逐渐减小,最大值出现在第Ⅳ级,可进入人体下呼吸道的室内外空气真菌粒径占比达85.0%以上。     

Geographical and temporal patterns of air-borne and personal 1,1,1-trichloroethane exposure in Piedmont region (Italy).

During the summer of 1989 and the winter 1989-1990, we initiated measurements of 1,1,1-trichloroethane concentrations in indoor, outdoor, and 'personal' air, in urban and rural sites. In the Piedmont region (North-Western Italy) we have carried out an atmospheric monitoring study: in the centre of Turin city (urban site), in Cuorgnè (rural site), and in Banchetta (remote site). First results confirm a higher winter contamination (11.67 vs. 2.79 micrograms/m3) and a higher contamination at the urban site, compared to rural and remote sites. Excluding Cuorgnè in the summer, all indoor/outdoor ratios are greater than 1 and, in all cases, the 'personal' air shows higher 1,1,1-trichloroethane levels than indoor and outdoor air. In Turin the relationships between winter and summer all show a higher winter contamination, while, in Cuorgnè no differences are proven.     

Chemical characterization of indoor and outdoor fine particulate matter in an occupied apartment in Rome,Italy

The daily concentration and chemical composition of PM_2.5 was determined in indoor and outdoor 24‐h samples simultaneously collected for a total of 5 weeks during a winter and a summer period in an apartment sited in Rome, Italy. The use of a specifically developed very quiet sampler (<35 dB) allowed the execution of the study while the family living in the apartment led its normal life. The indoor concentration of PM_2.5 showed a small seasonal variation, while outdoor values were much higher during the winter study. Outdoor sources were found to contribute significantly to indoor PM concentration especially during the summer, when the apartment was naturally ventilated by opening the windows. During the winter the infiltration of outdoor PM components was lower and mostly regulated by the particle dimensions. Organics displayed In/Out ratios higher than unity during both periods; their indoor production increased significantly during the weekends, where the family stayed mostly at home. PM components were grouped into macrosources (soil, sea, secondary inorganics, traffic, organics). During the summer the main contributions to outdoor PM_2.5 came from soil (30%), secondary inorganics (29%) and organics (22%). Organics dominated both indoor PM_2.5 during the summer (60%) and outdoor and indoor PM_2.5 during the winter (51% and 66%, respectively).     

Changing microbial concentrations are associated with ventilation performance in Taiwan's air-conditioned office buildings

Our study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research. Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings. PRACTICAL IMPLICATIONS: As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place.     

Indoor exposure levels of bacteria and fungi in residences,schools, and offices in China: A systematic review

Microbes in buildings have attracted extensive attention from both the research community and the general public due to their close relationship with human health. However, there still lacks comprehensive information on the indoor exposure level of microbes in China. This study systematically reviews exposure levels, the community structures, and the impact factors of airborne bacteria and fungi in residences, schools, and offices in China. We reviewed the major literature databases between 1980 and 2019 and selected 55 original studies based on a set of criteria. Results show that the concentration of indoor bacteria varies from 72.5 to 7500 CFU/m³, with a median value of 1000 CFU/m³, and the concentration of fungi varies from 12 to 9730 CFU/m³, with a median value of 526 CFU/m³. The concentration level of microbes varies in different climate zones, with higher bacterial concentrations in the severe cold zone, and higher fungal concentrations in the hot summer and warm winter zone. Among different buildings, classrooms have the highest average bacteria and fungi levels. This review reveals that a unified assessment system based on health effects is needed for evaluating the exposure levels of bacteria and fungi.     

Influence of environmental factors on airborne fungi in houses of Santa Fe City, Argentina

This study investigated concentration and types of airborne fungi spores of indoor air. Forty nine houses of Santa Fe city (Argentina) were examined during one year. This city is characterized by a warm climate with an annual mean temperature of 18.6 degrees C and a relative humidity of 74.6%. Based on similar characteristics, a group of representative houses were selected from both urban and suburban areas. The study began by evaluating the airborne fungal concentrations on environmental factors such as area (urban-suburban), season (winter-summer) and presence/absence of a convection gas-fired heating system during winter. Samples were taken with a Standard RCS centrifugal air sampler which operates on the principle of impact onto an agar media strip by centrifugal force. Strips were filled with malt extract agar containing chloramphenicol to inhibit bacterial growth. After incubation and identification, concentrations of airborne fungi were calculated as CFU/m(3). Indoor results showed the presence of thirteen dominant genera: Cladosporium (58.90%), Alternaria (8.68%), Epicoccum (5.74%), Fusarium (5.37%), Curvularia (3.50%), Acremonium (1.27%), Drechslera (1.26%), Penicillium (1.25%), Aspergillus (1.14%), Mucor (0.61%), Ulocladium (0.57%), Nigrospora (0.48%), Chrysosporium (0.42%) and yeast (3.74%), whose presence varied throughout the year. Multivariate Analyses of Variance were performed to study the influence of environmental factors on concentrations of fungal flora. The results obtained were significant for season (lambda=0.1225), area (lambda=0.6371) and for the presence of a convection gas-fired heating system during winter (lambda=0.4765). ANOVA test for the season showed the highest fungal levels (Geometric Mean) in the summer for Alternaria (181.97 CFU/m(3) vs. 17.38 CFU/m(3)), Fusarium (158.49 CFU/m(3) vs. 2.14 CFU/m(3)), Curvularia (66.07 CFU/m(3) vs. 1.62 CFU/m(3)), Acremonium (7.24 CFU/m(3) vs. 2.29 CFU/m(3)), Mucor (3.16 CFU/m(3) vs. 1.15 CFU/m(3)), Nigrospora (2.34 CFU/m(3) vs. 1.07 CFU/m(3)), Chrysosporium (2.73 CFU/m(3) vs. 1.23 CFU/m(3)). In winter, the highest levels (Geometric Mean) were for Penicillium (5.13 CFU/m(3) vs. 1.91 CFU/m(3)) and yeast (16.22 CFU/m(3) vs. 3.09 CFU/m(3)). As for the area, ANOVA showed the highest fungal levels (Geometric Mean) in suburban areas for Cladosporium (676.08 CFU/m(3) vs. 380.19 CFU/m(3)), Curvularia (6.76 CFU/m(3) vs. 4.27 CFU/m(3)) Ulocladium (3.31 CFU/m(3) vs. 1.20 CFU/m(3)) and yeast (18.62 CFU/m(3) vs. 4.90 CFU/m(3)), while Aspergillus (4.57 CFU/m(3) vs. 1.38 CFU/m(3)), showed the highest levels (Geometric Mean) in the urban area. On the other hand, only Cladosporium showed a higher level (Geometric Mean) in houses without convection gas-fired heating system during winter, compared to that corresponding to heated houses.     

Changes in profiles of airborne fungi in flooded homes in southern Taiwan after Typhoon Morakot

In August 2009, the historic Typhoon Morakot brought extreme rainfall and resulted in flooding which spread throughout southern Taiwan. This study compared the difference between fungal concentrations before and after the disaster in selected homes of the Tainan metropolitan area, which were hit hardest by the catastrophe. A group of 83 households available from a prior cohort established with random sampling out of a regional population in southern Taiwan was contacted successfully by telephone. Twenty-five of these reported to have suffered from floods of various degrees at this time. Around 2 weeks after the event, at which time most of the remedial process had been completed by self-efforts and public health endeavours, 14 of these 25 (56%) agreed to participate in measurements of the airborne microbial concentrations. The averages (standard deviation) of the total culturable fungal concentrations in children's bedrooms and flooded rooms were 18,181 (25,854) colony-forming units per cubic metre (CFU/m³) and 13,440 (11,033) CFU/m³, respectively. The airborne fungal spore levels in the 2 above-mentioned indoor sites were 221,536 (169,640) spores/m³ and 201,582 (137,091) spores/m³, respectively. The average indoor/outdoor ratios in the children's bedrooms were 4.2 for culturable fungi and 1.4 for fungal spores. These values were higher than the respective values measured in the same homes during the previous year: 1.1 and 0.6. In terms of the specific fungal profile, the percentages of Aspergillus spp. increased significantly in both the indoor and outdoor environments after the event. To this date, this study is among the limited research that has been conducted to quantitatively demonstrate that fungal manifestation is likely to persist in flooded homes even after seemingly robust remedial measures have been put into place. Studies to examine the potential health implications and effectiveness of better remedial technology remain much needed.     

Assessment of airborne bacteria and fungi in food courts

A study was undertaken to determine the effect of variations in temperature, relative humidity, occupancy density and location (indoor/outdoor) on the concentrations of viable airborne bacterial and fungal spores at an air-conditioned and a non air-conditioned food stall in Singapore. Typically, bioaerosols consisted of 50.5% bacteria and 49.5% fungi in the indoor environment. In contrast, for the outdoor environment, bacteria on an average only accounted for 20.6% of culturable airborne microorganisms whereas fungal concentrations were 79.4%. Results on bioaerosol size distributions revealed that 67% of indoor bacteria and 68% of outdoor bacteria, 85% of indoor fungi and 68% of outdoor fungi were associated with fine mode particulates (<3.3 μm). Occupant density was the key factor that affected indoor airborne bacteria concentrations while concentrations of outdoor airborne bacteria depended strongly on ambient temperature. Indoor fungal concentration was positively correlated to relative humidity whereas outdoor fungal concentration was positively correlated to relative humidity and negatively correlated to temperature. The study also compared the biological air quality between a non air-conditioned food stall (Stall A) and an air-conditioned food stall (Stall B). The dining area of the former had lower bacterial concentrations as compared to the latter, while fungal spore’s concentrations showed a reverse trend. The dominant airborne bacteria genera were Staphylococcus, Pseudomonas, Alcaligens, and Corynebacterium whereas Penicillium, Aspergillus and Cladosporium were the most common fungal genera and groups in both food stalls.     

Indoor air quality investigation at air-conditioned and non-air-conditioned markets in Hong Kong

To characterize indoor air quality at the markets in Hong Kong, three non-air-conditioned and two air-conditioned markets were selected for this study. The indoor air pollutants measured included PM(10) (particulate matters with aerodynamic diameter less than 10 microm), total bacteria count (TBC), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO(2)) and sulfur dioxide (SO(2)). The indoor and outdoor concentrations of these target air pollutants at these markets were measured and compared. The effects of air conditioning, temperature/relative humidity variation and different stalls on the indoor air quality were also investigated. The results indicated that all of the average indoor concentrations of PM(10), TBC, CO and NO(2) at the markets were below the Hong Kong Indoor Air Quality Objectives (HKIAQO) standards with a few exceptions for PM(10) and TBC. The elevated PM(10) concentrations at Hung Hom, Ngau Tau Kok and Wan Chai markets were probably due to the air filtration of outdoor airborne particulates emitted from vehicular exhaust, whereas high concentrations of airborne bacteria at Sai Ying Pun and Tin Shing markets were linked to the use of air conditioning. Correlation analysis demonstrated that indoor bacteria concentrations were correlated with temperature and relative humidity. The operation of air conditioning did not significantly reduce the levels of air pollutants at the markets. However, the higher indoor/outdoor ratios demonstrated that the operation of air conditioning had influence on the levels of bacteria at the markets. It was found that average PM(10) concentration at poultry stalls was higher than the HKIAQO standard of 180 microg/m(3), and was over two times that measured at vegetable, fish and meat stalls. Furthermore, the concentration of airborne bacteria at the poultry stalls was as high as 1031 CFU/m(3), which was above the HKIAQO standard of 1000 CFU/m(3). The bacteria levels at other three stalls were all below the HKIAQO standard. Statistical analysis indicated that there were no significant differences among the four stalls for CO, NO(x) and SO(2).     

Relationship between outdoor and indoor air quality in eight French schools

In the frame of the French national research program PRIMEQUAL (inter-ministry program for better air quality in urban environments), measurements of outdoor and indoor pollution have been carried out in eight schools in La Rochelle (France) and its suburbs. The buildings were naturally ventilated by opening the windows, or mechanically ventilated, and showed various air permeabilities. Ozone, nitrogen oxides (NO and NO(2)), and airborne particle (particle counts within 15 size intervals ranging from 0.3 to 15 mum) concentrations were continuously monitored indoors and outdoors for two 2-week periods. The indoor humidity, temperature, CO(2) concentration (an indicator of occupancy), window openings and building permeability were also measured. The temporal profiles of indoor and outdoor concentrations show ozone and nitrogen oxides behave differently: NO and NO(2) indoor/outdoor concentration ratios (I/O) were found to vary in a range from 0.5 to 1, and from 0.88 to 1, respectively, but no correlation with building permeability was observed. On the contrary, I/O ratios of ozone vary in a range from 0 to 0.45 and seem to be strongly influenced by the building air-tightness: the more airtight the building envelope, the lower the ratio. Occupancy, through re-suspension of previously deposited particles and possible particle generation, strongly influences the indoor concentration level of airborne particles. However, this influence decreases with particle size, reflecting the way deposition velocities vary as a function of size. The influence of particle size on deposition and penetration across the building envelope is also discussed by analyzing the I/O ratios measured when the buildings were unoccupied, by comparing the indoor concentrations measured when the buildings were occupied and when they were not (O/U ratios), and by referring to previously published studies focussing on this topic. Except one case, I/O were found to vary in the range from 0.03 to 1.79. All O/U are greater than one and increase up to 100 with particle size. PRACTICAL IMPLICATIONS: Assessing children's total exposure requires the knowledge of outdoor and indoor air contaminant concentrations. The study presented here provides data on compared outdoor and indoor concentration levels in school buildings, as well as information on the parameters influencing the relationship between outdoor and indoor air quality. It may be used as a basis for estimating indoor concentrations from outdoor concentrations data, or as a first step in designing buildings sheltering children against atmospheric pollution.     

Characterizing ultrafine particles and other air pollutants at five schools in South Texas

This study examined five schools with different ventilation systems in both urban and rural areas in South Texas. Total particle number concentration, ultrafine particle (UFP, diameter < 100 nm) size distribution, PM(2.5) , and CO(2) were measured simultaneously inside and outside of various school microenvironments. Human activities, ventilation settings, and occupancy were recorded. The study found a greater variation of indoor particle number concentration (0.6 × 10(3) -29.3 × 10(3) #/cm(3) ) than of outdoor (1.6 × 10(3) -16.0 × 10(3) #/cm(3) ). The most important factors affecting indoor UFP levels were related to various indoor sources. Gas fan heaters increased the indoor-to-outdoor ratio (I/O ratio) of total particle number concentrations to 30.0. Food-related activities, cleaning, and painting also contributed to the increased indoor particle number concentration with I/O ratios larger than 1.0. Without indoor sources, the I/O ratios for total particles varied from 0.12 to 0.66 for the five ventilation systems studied. The I/O ratio decreased when the outdoor total particle number concentration increased. Particles with diameters <60 nm were less likely to penetrate and stay airborne in indoor environments than larger particles and were measured with smaller I/O ratios. PRACTICAL IMPLICATIONS: From an exposure assessment perspective, schools are important and little-studied microenvironments where students congregate and spend a large proportion of their active time. This study provides information for indoor and outdoor ultrafine particle concentrations at different types of school microenvironments. These data may allow future epidemiological studies to better estimate exposure and assess ultrafine particles health effects among students.     

不同气候区城市公共建筑内微生物浓度对比分析

为研究不同气候区公共建筑室内微生物污染状况,选取昆明和南京分别代表温和地区和夏热冬冷地区,对医院和办公楼2类公共建筑内的微生物浓度进行了测量和分析。结果表明:温和气候区内医院细菌和真菌平均浓度分别为520、316 cfu/m³,办公楼细菌和真菌平均浓度分别为369、520 cfu/m³,均高于夏热冬冷气候区对应类型公共建筑;2个气候区室内细菌、真菌粒径分布相似,峰值均出现在粒径范围Ⅳ级(2.1~3.3μm)和Ⅴ级(1.1~2.1μm);2个气候区公共建筑室内相对湿度和空气真菌浓度存在确定关系,除此之外,仅在昆明医院内发现温度和微生物浓度之间存在显著相关性。     

Airborne viable, non-viable, and allergenic fungi in a rural agricultural area of India: a 2-year study at five outdoor sampling stations

The information on airborne allergenic fungal flora in rural agricultural areas is largely lacking. Adequate information is not available to the bioaerosol researchers regarding the choice of single versus multiple sampling stations for the monitoring of both viable and non-viable airborne fungi. There is no long-term study estimating the ratios of viable and non-viable fungi in the air and earlier studies did not focus on the fractions of airborne allergenic fungi with respect to the total airborne fungal load. To fill these knowledge gaps, volumetric paired assessments of airborne viable and non-viable fungi were performed in five outdoor sampling stations during two consecutive years in a rural agricultural area of India. Samples were collected at 10-day intervals by the Burkard Personal Slide Sampler and the Andersen Two-Stage Viable Sampler. The data on the concentrations of total and individual fungal types from five stations and 2 different years were analyzed and compared by statistical methods. The allergenicity of the prevalent airborne viable fungi was estimated by the skin-prick tests of >100 rural allergy patients using the antigenic fungal extracts from isolates collected with the Andersen sampler. The ranges of total fungal spore concentration were 82-2365 spores per cubic meter of air (spores/m3) in the first sampling year and 156-2022 spores/m3 in the second sampling year. The concentration ranges of viable fungi were 72-1796 colony-forming units per cubic meter of air (CFU/m3) in the first sampling year and 155-1256 CFU/m3 in the second sampling year. No statistically significant difference was observed between the total spore data of the 2 years, however, the data between five stations showed a significant difference (P<0.0001). No statistically significant difference existed between stations and years with respect to the concentration of viable fungi. When the data of individual allergenic fungal concentrations were compared between stations and years, no statistically significant difference was observed in all cases except for Aspergillus japonicus and Rhizopus nigricans, which showed significant difference in case of stations and years, respectively. The ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler from all sampling stations ranged between 0.29 and 7.61. The antigenic extracts of eight prevalent viable airborne fungi (A. flavus, A. japonicus, A. fumigatus, Alternaria alternata, Cladosporium cladosporioides, Curvularia pallescens, Fusarium roseum, and R. nigricans) demonstrated >60% positive reactions in the skin prick test. These selected allergenic fungi collectively represented 31.7-63.2% of the total airborne viable fungi in different stations. The study concluded that: (i) a rich fungal airspora existed in the rural study area, (ii) to achieve representative information on the total airborne fungal spores of an area, the monitoring in multiple sampling stations is preferable over a single sampling station; for viable fungi, however, one station can be considered, (iii) the percentage of airborne fungal viability is higher in rural agricultural areas, and (iv) approximately 52% of the viable airborne fungi in the rural study area were allergenic.     

Profiles and seasonal distribution of airborne fungi in indoor and outdoor environments at a French hospital

A one-year prospective survey of fungal air contamination was conducted in outdoor air and inside two haematological units of a French hospital. Air was sampled with a portable Air System Impactor. During this period of survey, the mean viable fungal load was 122.1 cfu/m³ in outdoor air samples, and 4.1 and 3.9 cfu/m³ in samples from adult and pediatric haematology units, respectively. In outdoor samples, Cladosporium was the dominant genus (55%) while in the clinical units, Penicillium sp. (23 to 25%), Aspergillus sp. (15 to 23%) and Bjerkandera adusta (11 to 13%) were the most frequently recovered airborne fungi. The outdoor fungal load was far higher in autumn (168 cfu/m³), spring (110 cfu/m³) and summer (138 cfu/m³) than in winter (49 cfu/m³). In indoor air, fungal concentrations were significantly lower in winter (2.7 to 3.1 cfu/m³) than in summer (4.2 to 5.0 cfu/m³) in both haematology units. In the outdoor environment, Penicillium sp. and Aspergillus sp. were more abundant in winter while the levels of Cladosporium were lowest during this season. In the haematological units, the presence of Aspergillus sp. was stable during the year (close to 20%), Bjerkandera sp. was particularly abundant in winter (close to 30%); levels of Penicillium sp. were highest in autumn while levels of Cladosporium sp. were highest in spring and summer.     

Multi-route trihalomethane exposure in households using municipal tap water treated with chlorine or ozone-chlorine

In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap water treated with ozone-chlorine or chlorine are unavailable or very limited. Accordingly, the present study was designed to obtain those data by measurements of the THM concentrations in the tap water and indoor and outdoor air in the two types of households, along with an estimation of THM exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THM in all three media, yet no bromoform was detected in any sample. Similar to previous findings, the winter chloroform concentration in tap water treated with chlorine (22.1 microg/l, median) was significantly higher than that in the tap water treated with ozone-chlorine (16.8 microg/l, median). However, the summer water chloroform concentrations and summer and winter water concentrations of the other two THMs (bromodichloromethane and dibromochloromethane) exhibited no significant difference between the chlorine and ozone-chlorine-treated water. It was suggested that the effects of the water parameters including biochemical oxygen demand of raw water entering water treatment plants should be considered when evaluating the advantage of ozone-chlorine disinfection for THM formation over chlorine disinfection. The indoor air THM concentration trend was also consistent with the water concentration trend. The indoor to outdoor air concentration ratios were comparable with previous studies. The THM exposure estimates from water ingestion, showering, and the inhalation of apartment indoor air when not in the shower suggested that, for residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water uses. The THM exposure estimates from tap water ingestion were similar to those from showering.     

Indoor and outdoor concentrations of Japanese cedar pollens and total suspended particulates: A case study at a kindergarten in Japan

Japanese cedar pollinosis (JCP) caused by allergenic cedar and cypress pollens is one of major economic and health issues in Japan. The present study reported here aimed to provide basic data to understand the status of early life exposures to airborne cedar and cypress pollens in school settings. In particular, the study investigated relationships between indoor and outdoor concentrations of airborne cedar and cypress pollens and total suspended particulates (TSP) in a kindergarten in Japan. Overall, outdoor concentrations of the airborne pollens and TSP were higher than the indoor concentrations, i.e., indoor to outdoor (I/O) ratios of 0.043–0.055 and 0.545 for the airborne pollens and TSP, respectively. The smaller I/O ratios for the pollens were expected because the larger pollen grains (20–30 μm in diameter) were less likely penetrated to indoor environment than for smaller airborne particulates. The present study also found increased TSP concentrations during the pollen season was likely attributed to increased airborne pollen concentrations. By understanding the status of indoor and outdoor concentrations of airborne cedar and cypress pollens in school settings, early life exposures to these allergenic pollens should be effectively minimized to prevent subsequent progression to JCP symptoms.     

A pilot investigation into associations between indoor airborne fungal and non-biological particle concentrations in residential houses in Brisbane,Australia

Indoor air contains a complex mixture of bioaerosols such as fungi, bacteria and allergens, as well as non-biological particles including products from various combustion processes. To date little work has been done to investigate the interactions and associations between particles of biological and non-biological origin, however, any occurring interactions could affect pollutant behaviour in the air and ultimately the effect they have on health. The aim of this work was to examine associations between the concentration levels of airborne particles and fungi measured in 14 residential suburban houses in Brisbane. The most frequently isolated fungal genus was Cladosporium, Curvularia, Alternaria, Fusarium and Penicillium. The average outdoor and indoor (living room) concentrations of fungal colony forming units were 1133+/-759 and 810+/-389, respectively. Average outdoor and indoor (normal ventilation) concentrations of submicrometre and supermicrometre particles were 23.8 x 10(3) and 21.7 x 10(3) (particles/cm(3)), 1.78 and 1.74 (particles/cm(3)), respectively. The study showed that no statistically significant associations between the fungal spore and submicrometre particle concentrations or PM(2.5) were present, while a weak but statistically significant relationship was found between fungal and supermicrometre particle concentrations (for the outdoors R(2)=0.4, P=0.03 and for a living room R(2)=0.3, P=0.04). A similarity in behaviour between the submicrometre particle and fungal spore concentrations was that the fungal spore concentrations were related directly to the distance from the source (a nearby park), in a very similar way in which the submicrometre particles originating from vehicle emissions from a road, were dependent on the distance to the road. In the immediate proximity to the park, fungal concentrations rose up to approximately 3100 CFU/m(3), whereas for houses more than 150 m away from the park the concentrations of fungi were below 1000 CFU/m(3). Recommendations have been provided as the future study designs to gain a deeper insight into the relationships between biological and non-biological particles.