Development and validation of a dynamic mass-balance prediction model for indoor particle concentrations in an office room

The Korean government recommends intermittent operation of air purifiers (APs) as a measure to maintain indoor particulate matter (PM) concentrations below the mandatory standards and reduce exposure to indr PM2.5 (PM with a diameter smaller than 2.5   μ m ). However, there is no guideline to inform occupants of when and how long APs should be operated to comply with the standards. In this study, we developed a dynamic mass-balance model to predict indoor PM concentrations in an office considering penetration of outdoor particles, change in number of occupants, and operational status of the AP. The model fit and prediction accuracies were verified using the American Society for Testing and Materials (ASTM) D 5157 criteria and the k-fold validation technique. We observed that indoor PM2.5 concentrations were determined by infiltration of outdoor PM2.5, and indoor generation/resuspension by occupants and removal. For PM 2.5 - 10 ( 2.5   μ m < diameter < 10   μ m ) , the indoor concentrations were determined by interior door access and indoor generation/resuspension. The operation of an AP effectively decreased indoor PM2.5 concentration but not PM2.5-10. We found that our model accurately predicted indoor PM concentrations. Therefore, using the developed model, a guideline may recommend: 1) start the AP when the predicted indoor PM2.5 concentrations under no AP operation approached the standard (e.g., 90% of the standard); and 2) stop the AP when the indoor PM2.5 concentration predicted under the assumption of no AP operation fell below the standard (e.g., 80% of the standard).

Estimating long-term time-resolved indoor PM2.5 of outdoor and indoor origin using easily obtainable inputs

To evaluate the separate impacts on human health and establish effective control strategies, it is crucial to estimate the contribution of outdoor infiltration and indoor emission to indoor PM_2.5 in buildings. This study used an algorithm to automatically estimate the long-term time-resolved indoor PM_2.5 of outdoor and indoor origin in real apartments with natural ventilation. The inputs for the algorithm were only the time-resolved indoor/outdoor PM_2.5 concentrations and occupants' window actions, which were easily obtained from the low-cost sensors. This study first applied the algorithm in an apartment in Tianjin, China. The indoor/outdoor contribution to the gross indoor exposure and time-resolved infiltration factor were automatically estimated using the algorithm. The influence of outdoor PM_2.5 data source and algorithm parameters on the estimated results was analyzed. The algorithm was then applied in four other apartments located in Chongqing, Shenyang, Xi'an, and Urumqi to further demonstrate its feasibility. The results provided indirect evidence, such as the plausible explanations for seasonal and spatial variation, to partially support the success of the algorithm used in real apartments. Through the analysis, this study also identified several further development directions to facilitate the practical applications of the algorithm, such as robust long-term outdoor PM_2.5  monitoring using low-cost light-scattering sensors.

Estimates of emission strengths of 43 VOCs in wintertime residential indoor environments, Beijing

There are many sources of volatile organic compounds (VOCs) in indoor environments, leading to much higher total indoor VOC concentrations than outdoor counterparts. Given the potential health hazards associated with VOC exposure, it is necessary to estimate the indoor VOC emission strengths. In this study, the indoor and outdoor concentrations of 43 VOCs were concurrently measured in 8 urban residences, Beijing. The indoor/outdoor concentration ratio was used to screen out 36 species having significant indoor sources. A one-compartment steady-state model was developed to estimate the indoor emission strengths of these VOCs, in which ventilation and reaction with ozone were included as sink routes. The order of VOCs in terms of indoor emission strength was d-limonene (a median value of 1.05 g/h), α-pinene (82.50 mg/h), styrene (24.12 mg/h), ß-pinene (9.70 mg/h), formaldehyde (1.97 mg/h), n-dodecane (1.82 mg/h), n-pentadecane (1.66 mg/h), n-hexadecane (1.62 mg/h), n-undecane (1.20 mg/h), acetaldehyde (1.05 mg/h) and 1, 4-dichlorobenzene (0.80 mg/h). The sum of estimates of those VOCs accounted for >95% of total emission strength. Specific indoor sources of those VOCs in the tested homes were identified. Air exchange rate, indoor temperature and air humidity were found to pose significant impacts to the indoor emission strengths of VOCs.

Elemental and microbiota content in indoor and outdoor air using recuperation unit filters

This paper presents the results of a twelve-month measurement campaign conducted at a rural single-family house in Poland. The external and internal filters of a recuperator used to mechanically ventilate the building were used to separate the total suspended particles (TSPs), and the concentrations of fifteen elements and abundance of fungi and bacteria were determined. Lower annual mean concentrations were observed indoors, and the concentrations of most elements did not significantly change between seasons. There were some differences between winter and summer, which may have resulted from changes in the ventilation regimes in the house. The number of bacteria was similar outdoors and indoors, while the amounts of fungi were higher indoors (p < 0.05). The order of metal concentrations outdoors agreed well with observations in other countries, while indoors the metal concentrations order indicated the individual characteristics of the building. The species diversity of fungi was higher than that of bacteria, and different species were found indoors and outdoors, while bacteria were typically present both indoors and outdoors. Different TSP sources were identified indoors and outdoors, suggesting limited penetration between the two environments. However, both environments were affected by traffic. Mechanical ventilation systems with built-in filters (such as recuperators) were useful in assessing the air quality within the building, and the changeable recuperation filters offer an approach to assess the air quality in several houses without any additional cost or discomfort to the residents.

Effect of indoor and outdoor sources on indoor particle concentrations in South Korean residential buildings

The rising indoor air pollution from particles is a cause for concern especially in houses where children and the elderly reside. In South Korea, assessment of exposure to particle number (PN) in residential apartments, which account for 76% of all houses, is limited. In our study, the indoor and outdoor PN (sizes 0.3-10.0 µm) concentrations were measured in ten typical apartments for 24 h each. In addition, the occupants' schedules were examined by conducting a survey. Results showed that the average outdoor PN concentrations were 0.30-4.37 × 10⁹/m³ with very large deviations. Indoor peak events were mainly caused by cooking, and total emitted particles were 0.01-81.3 × 10¹³ particles. Indoor PN concentrations were sustained for a long time because of inefficient ventilation that led to lowered attenuation. Indoor particles are generated during various indoor activities. The daily-integrated particle exposures were 21.4% and 78.6% for indoor and outdoor sources, respectively. Thus, outdoor sources were the predominant sources of particle exposure compared with indoor sources. In conclusion, penetration from outdoor sources needs to be reduced by adding air filtration to improve the airtightness of buildings when introducing outdoor air to lower the indoor PN concentration.

Source characterization and health risks of BTEX in indoor/outdoor air during winters at a terai precinct of North India

BTEX are the consistently found air contaminants in indoor and outdoor environments. In order to investigate the exposure levels of BTEX, the indoor and outdoor air was analyzed during winter season at homes located at four selected sites of Gorakhpur, Uttar Pradesh, India, which comprised residential, roadside, industrial and agricultural areas. BTEX were sampled with a low-flow pump (SKC model 220). Samples were extracted with CS₂ and the aromatic fraction was subjected to GC-FID. Mean indoor concentration of BTEX was highest at the agricultural (70.9 µg m^-3) followed by industrial (30.0 µg m^-3), roadside (17.5 µg m^-3) and residential site (11.8 µg m^-3). At outdoor locations, the mean BTEX levels were highest at the roadside (22.0 µg m^-3) followed by industrial (18.7 µg m^-3), agricultural (11.0 µg m^-3) and residential site (9.1 µg m^-3). The I/O ratios were greater than 1 at all the sites except roadside site, where I/O ratios for toluene, ethylbenzene and xylene were less than unity. Poor correlation between indoor and outdoor levels at each site further indicated the dominance of indoor sources. Factor analysis followed by one-way analysis of variance depicts that the presence of BTEX compounds at all the sites indicate a mixture of vehicular and combustion activities. For benzene, the ILTCR values exceeded the safe levels, whereas ethylbenzene was nearby to the recommended level 1 × 10^-6. The HQ values were above unity for agricultural (indoors) and industrial (outdoors) as an exception to all the other sites which indicted the value below unity.

Role of resuscitation ratio in monitoring burn patients

INTRODUCTION

Efforts with the utilization of an Input/Output ratio (I/O ratio) are done with success for analyzing and moving forward the treatment in the resuscitation phase of the burn patient. The need for conducting this research is to apply the I/O ratio in our cohort as a helpful index for classifying the resuscitation response of the burn patients. Our prespecified hypothesis is if it matters the analysis of the I/O ratio at 8 h of fluid resuscitation period.

MATERIAL AND METHOD

This prospective observational study was performed in 50 patients (22 adults and 28 children) admitted in the Intensive Care of the Service of Burns in Tirana, Albania in the period January to December 2016. We calculated the I/O ratio at 8 h and the end of the 1st 24 h based on the stratification of patients according to the ratio in respective groups. In the adult population we did an analysis whereby the ratio I/O at 8 h has a relationship with the 24 h results as well as with ICU-free days.

RESULTS

The 24 h fluid resuscitation was done with the majority clustered in the range 2-4 ml/kg/% TBSA with fluid-weight score (ml/kg) correlated with % TBSA. After calculation of the I/O ratio at 8 h, 29 patients were assigned in over-responders (<0.166), 16 patients in the expected group(0.166-0.334), and 5 patients were assigned in under-responders (>0.334). There is a strong correlation between the I/O ratio at 8 h and the I/O ratio at 24 h and I/O ratio predict better the longer ICU-free days.

CONCLUSIONS

The I/O ratio is a very useful parameter not only at 12 h and 24 h but also at 8 h after burns. By classifying the patients into outcome groups that reflect not only the volume given but moreover the physiologic reactions to the resuscitation volume gotten, we were more attentive to patients in under-responders at 8 h. This parameter fulfills the criteria for better classifying patients and a better understanding of the physiology of burns.

Indoor air quality indicators and toxicity potential at the hospitals' environment in Dhaka, Bangladesh

Indoor air quality (IAQ) is a leading apprehension currently especially in the perilous atmosphere, like hospitals. Clean and fresh air is very crucial for the patients and healthcare professionals in the hospitals. Therefore, we examined IAQ indicators (PM_1.0, PM_2.5, PM₁₀, NO₂, CO₂, and TVOC) at sixteen locations of three hospitals with an emphasis on seasonal variations, indoor/outdoor correlation, and concomitant toxicity potential (TP) of human exposure between October 2019 and January 2020. For the measurement of trace gases (NO₂, CO₂, and TVOC), Aeroqual 500 series (New Zealand) sampler was used; particulate matter (PM_1.0, PM_2.5, and PM₁₀) concentrations and relative humidity (RH) were measured using the IGERESS air quality monitoring device (WP6930S, China). The total average concentration of IAQ indicators were 104.1 ± 67.6 (PM_1.0), 137.4 ± 89.2 (PM_2.5), and 159.0 ± 103.3 (PM₁₀) μgm^-3; 0.11 ± 0.02 (NO₂), 1047.1 ± 234.2 (CO₂), and 176.5 ± 117.7 (TVOC) ppm. Significant variations of IAQ indicators were observed between different locations of the hospitals. Winter IAQ indicators were much higher than post-monsoon season. Indoor particulate matter (PM) levels were lower than outdoor, but gaseous pollutants were higher in indoor than outdoor except NO₂. Indoor TVOC was about two times higher than outdoor and also higher in post-monsoon than winter. A good positive correlation was observed between indoor and outdoor particulate matter during winter. A strong positive correlation was obtained between NO₂ and RH with PM in winter. Very high (> 10) indoor toxicity potential (TP) values of PM_2.5 and PM₁₀ were determined during winter. Extremely high TP values indicated potential severe health consequences of the healthcare professionals and patients in indoor hospitals' environment.

Airborne particles and microorganisms in a dental clinic: Variability of indoor concentrations, impact of dental procedures, and personal exposure during everyday practice

This study presents for the first time comprehensive measurements of the particle number size distribution (10 nm to 10 μm) together with next-generation sequencing analysis of airborne bacteria inside a dental clinic. A substantial enrichment of the indoor environment with new particles in all size classes was identified by both activities to background and indoor/outdoor (I/O) ratios. Grinding and drilling were the principal dental activities to produce new particles in the air, closely followed by polishing. Illumina MiSeq sequencing of 16S rRNA of bioaerosol collected indoors revealed the presence of 86 bacterial genera, 26 of them previously characterized as potential human pathogens. Bacterial species richness and concentration determined both by qPCR, and culture-dependent analysis were significantly higher in the treatment room. Bacterial load of the treatment room impacted in the nearby waiting room where no dental procedures took place. I/O ratio of bacterial concentration in the treatment room followed the fluctuation of I/O ratio of airborne particles in the biology-relevant size classes of 1-2.5, 2.5-5, and 5-10 μm. Exposure analysis revealed increased inhaled number of particles and microorganisms during dental procedures. These findings provide a detailed insight on airborne particles of both biotic and abiotic origin in a dental clinic.

Concurrent assessment of personal, indoor, and outdoor PM2.5 and PM1 levels and source contributions using novel low-cost sensing devices

The intensity, frequency, duration, and contribution of distinct PM2.5 sources in Asian households have seldom been assessed; these are evaluated in this work with concurrent personal, indoor, and outdoor PM2.5 and PM1 monitoring using novel low-cost sensing (LCS) devices, AS-LUNG. GRIMM-comparable observations were acquired by the corrected AS-LUNG readings, with R2 up to 0.998. Twenty-six non-smoking healthy adults were recruited in Taiwan in 2018 for 7-day personal, home indoor, and home outdoor PM monitoring. The results showed 5-min PM2.5 and PM1 exposures of 11.2 ± 10.9 and 10.5 ± 9.8 µg/m3 , respectively. Cooking occurred most frequently; cooking with and without solid fuel contributed to high PM2.5 increments of 76.5 and 183.8 µg/m3 (1 min), respectively. Incense burning had the highest mean PM2.5 indoor/outdoor (1.44 ± 1.44) ratios at home and on average the highest 5-min PM2.5 increments (15.0 µg/m3 ) to indoor levels, among all single sources. Certain events accounted for 14.0%-39.6% of subjects' daily exposures. With the high resolution of AS-LUNG data and detailed time-activity diaries, the impacts of sources and ventilations were assessed in detail.

Size-resolved dynamics of indoor and outdoor fluorescent biological aerosol particles in a bedroom: A one-month case study in Singapore

This study evaluated the interrelations between indoor and outdoor bioaerosols in a bedroom under a living condition. Two wideband integrated bioaerosol sensors were utilized to measure indoor and outdoor particulate matter (PM) and fluorescent biological airborne particles (FBAPs), which were within a size range of 0.5-20 μm. Throughout this one-month case study, the median proportion of FBAPs in PM by number was 19% (5%; the interquartile range, hereafter) and 17% (3%) for indoors and outdoors, respectively, and those by mass were 78% (12%) and 55% (9%). According to the size-resolved data, FBAPs dominated above 2 and 3.5 μm indoors and outdoors, respectively. Comparing indoor upon outdoor ratios among occupancy and window conditions, the indoor FBAPs larger than 3.16 μm were dominated by indoor sources, while non-FBAPs were mainly from outdoors. The occupant dominated the indoor source of both FBAPs and non-FBAPs. Under awake and asleep, count- and mass-based mean emission rates were 45.9 and 18.7 × 10⁶ #/h and 5.02 and 2.83 mg/h, respectively. Based on indoor activities and local outdoor air quality in Singapore, this study recommended opening the window when awake and closing it during sleep to lower indoor bioaerosol exposure.

Experimental Investigation of Air Quality in a Subway Station with Fully Enclosed Platform Screen Doors

In this study, the indoor air quality (IAQ) was investigated in a subway station with fully enclosed platform screen doors in Beijing, China. Eight indoor air pollutants, including PM2.5, PM10, SO2 (sulfur dioxide), NO2 (nitrogen dioxide), NH3 (ammonia), CO (carbon monoxide), CH2O (formaldehyde) and TVOC (total volatile organic compound), were measured for six consecutive days in October 2019. The results indicated that the IAQ in the subway station was basically stable at good levels for most times during the whole measurement period. All eight indoor air pollutants were far below their corresponding maximum allowable concentrations, except for the PM2.5 concentrations, which occasionally exceeded the concentration limits. The concentrations of indoor air pollutants in the subway station were basically within the corresponding standards. The correlation analyses showed that outdoor air pollutants have important influences on indoor air pollutants. The concentrations of PM10, PM2.5, SO2, NO2 and CO in the subway station were positively correlated with their corresponding outdoor concentrations. PM10 was statistically significantly correlated with the passenger flow and train frequency, but the other air pollutants were less impacted by the passenger flow and train frequency.

PM2.5 mass concentration variation in urban residential buildings during heating season in severe cold region of China: A case study in Harbin

Recent years, people pay great attention to fine particle matter (PM_2.5) in indoor environment due to its negative impacts on health. Household cooking and severe air pollutant aggravate indoor PM_2.5 level, especially during heating season in severe cold region of China. To find the variation of actual household PM_2.5 influenced by both cooking activities and penetration from outdoor environment, a field measurement of PM_2.5 concentrations in living room of residential buildings was conducted in Harbin, China. Firstly, six households in urban residence were selected to monitor the indoor PM_2.5 mass concentration sequentially. Simultaneously, outdoor PM_2.5 concentrations, temperature and indoor occupants' behavior were collected. Secondly, indoor to outdoor (I/O) ratios of PM_2.5 in each household during monitoring campaigns were calculated. Influence of cooking activities and outdoor penetration on indoor PM_2.5 concentrations in living room were also analyzed. Thirdly, some discussions were done for explanation of variation of PM_2.5 in urban residential buildings. Results showed that the average PM_2.5 mass concentrations varied from 11.7 to 48.6 μg/m³ indoor, while average I/O ratio value ranged from 0.33 to 1.23. Cooking in kitchen had significant impact on PM_2.5 mass concentrations in living room, especially when frying, which could lead to peak value of 456.8 μg/m³ within 10 min from background level. Penetration led to the indoor PM_2.5 level approximately 2 h behind with outdoor PM_2.5 concentrations in general residences.

Assessment of culturable airborne bacteria of indoor environments in classrooms, dormitories and dining hall at university: a case study in China

University students' health may be adversely affected by exposure to indoor bacterial contaminants on their campuses. This study aims (1) to quantify culturable bacterial concentrations in three indoor environments at a university, (2) to investigate the influence of meteorological factors and gender, to assess the relationship between indoor and outdoor, and (3) to estimate the bacterial dose for university students in different indoor environments. Airborne bacteria samples were collected in 12 classrooms, in 12 living rooms and four bathrooms in two dormitory buildings, and in a dining hall. The results showed that the microenvironment in the female dormitory had the highest mean bacterial concentration (2847 CFU/m³), whereas the lowest mean bacterial concentration was observed in classrooms (162 CFU/m³). Indoor bacterial concentrations in male dormitories were significantly lower than in female dormitories probably because of crowding and increased ventilation. Outdoor weather conditions were associated with the indoor concentrations with regard to insufficient ventilation and varying outdoor concentration. The occupants' activity level was also more closely related to the indoor bacteria concentration in the residential setting. Students experienced about four times higher dose of airborne bacteria in the dormitories than in the classrooms and dining hall.

Contributions of Indoor and Outdoor Sources to Ozone in Residential Buildings in Nanjing

Ozone has become one of the most serious air pollutants in China in recent years. Since people spend most of their time indoors, the ozone in the indoor environment could be a major factor affecting the occupants’ health. The indoor ozone in residential buildings mainly comes from two sources: outdoor atmosphere and indoor ozone produced by electrical devices. In this study, a typical residence in Nanjing was taken as an example to calculate and compare the contributions of indoor and outdoor sources to ozone in the building. A questionnaire survey about the type, the placement, and the frequency of use of the ozone emission devices was performed to provide the basis for the settings of indoor ozone sources. The multi-zone software CONTAM was used hourly to simulate the ozone concentration in summer and in winter with inner doors either closed or open, and it was noted whether there were ozone emission devices indoors or not. Source contribution was quantified and compared by three methods in this paper: (1) the average indoor/outdoor (I/O) ratio, (2) the I/O ratio frequency, and (3) the ratio of indoor ozone concentration without ozone sources to that with ozone sources. The results showed that the contribution of outdoor sources was much greater than that of indoor sources in summer, but in winter, the frequency of I/O > 1 could reach 55.8% of the total seasonal time, and the ratio of indoor ozone concentration without sources to that with sources could reach as high as 74.3%. This meant that the indoor concentration had the potential to exceed the outdoor. Furthermore, human respiratory exposure in different ages and genders was calculated. It was found that teenagers aged 10–18 years old and female adults had a higher respiratory exposure level.

Assessing the seasonality of occupancy number-associated CO2 level in a Taiwan hospital

This study enabled the assessment of indoor CO₂ levels and evaluated the relationship between occupancy numbers with CO₂ levels in a Taiwan hospital. The measurements were conducted over four seasons for five working days (Monday to Friday), with sampling conducted simultaneously from 09:00 am to 5:00 pm and across six locations (for spatial variability): hall (H), registration and cashier (RC), waiting area (WA), occupational therapy room (OT), physical therapy room (PT), and outdoors (O). Based on the analysis, three of the five indoor sampling sites showed significant differences in seasonal CO₂ concentrations (p < 0.0001). Based on our result, the physical therapy room had the highest level of CO₂ concentration that exceeded the IAQ standard in Taiwan Environmental Protection Agency (EPA) in all seasons, in that the number of occupants contributing to nearly 40% of the variation in CO₂ measured. Our results also showed that the indoor/outdoor (I/O) ratios of CO₂ concentration for all locations and seasons exceeded 1 in ~ 100% of those locations. The median I/O ratio at sites WA and OT was 2.37 and 2.08 during four seasons, respectively. The highest median I/O ratio was found at site PT, with a calculated range of 2.69 in spring to 3.90 in fall. The highest correlation of occupancy number and CO₂ concentration also occurred in PT which correlation coefficients were estimated at 0.47, 0.65, 0.63, and 0.40 in spring, summer, fall, and winter. The findings of the present study can be used to understand occupancy number and its effect on CO₂ levels in a hospital environment, as well as the effect of time of day (Monday to Friday) on the number of patients admitted.

Redistribution of PM2.5 -associated nitrate and ammonium during outdoor-to-indoor transport

Nitrate and ammonium ions are major constituents of outdoor PM_2.5 . Human exposure to these ions occurs primarily indoors. To assess the adverse outcomes from exposure to them, it is necessary to quantify the relationships between outdoor and indoor PM_2.5 nitrate and ammonium. The relationships for the two semi-volatile ions are more complex than those of non-volatile PM_2.5 constituents (eg, sulfate, elemental carbon). This study presents a mechanistic description of their outdoor-indoor relationships that incorporates a dynamic gas-particle partitioning and key parameters such as the pH and water content of PM_2.5 . Compared to measurements of nitrate and ammonium, the model has normalized mean biases of -9% and -42% and correlation coefficients of 0.95 and 0.68 for nitrate and ammonium, respectively. This suggests satisfactory agreement for nitrate, but less strong for ammonium. Sensitivity analysis on key parameters indicates that the model generally works well across a range of values typical of indoor settings. The model's performance is sensitive to pH and water content in PM_2.5 , which control the gas-particle partitioning process. Indoor PM_2.5 tends to be more acidic than outdoor PM_2.5 , raising potential health concern. The model provides insights in exposure assessment, source apportionment, and health-composition attribution of indoor PM_2.5 .

Effectiveness of Airborne Fungi Removal by using a HEPA Air Purifier Fan in Houses

Few studies have evaluated the performance of air purifiers in removing airborne fungi in houses. Here, we evaluated the ability of a HEPA air purifier fan to remove airborne fungi in six houses in Japan. In each house, the number of airborne fungi decreased more rapidly when the air purifier fan was on (test measurement) than when it was off (control) , demonstrating its ability to decrease the fungal concentration. The number of airborne fungi decreased between 1.5 and 6 times faster when the air purifier fan was on than when it was off (spontaneous decrease) . Clean air change rates, calculated from measurements taken 15 min after the test equipment operation began, ranged from 2.9 to 5.4 (h^-1) , indicating adequate air cleaning. One of the six test houses contained a much greater concentration of airborne fungi than the standard set by the Architectural Institute of Japan. When the air purifier fan was operated in the house, the indoor/outdoor (I/O) ratio decreased from 77.5, equating to a fungal concentration of 53,000 cfu/m³ at 0 min to 0.72 or 620 cfu/m³ after 45 min, which is below the standard. This reduction clearly demonstrated the antifungal effect of the air purifier fan.

Study on the relationship between the concentration and type of fungal bio-aerosols at indoor and outdoor air in the Children's Medical Center, Tehran, Iran

Fungal bio-aerosols are of concern due to their adverse health effects, especially in indoor environments. The aim of this study was to evaluate the relationship between the concentration and type of fungal bio-aerosols in the indoor and outdoor of Children's Medical Center in Tehran, Iran. In the present descriptive-analytical study, the fungal bio-aerosols' concentrations in both indoor and outdoor of the hospital air were measured. The measurements were carried out by the Anderson method using a Quick Take 30 pump at 28.3 L min^-1 and 2.5 min sampling that was placed on a Sabouraud dextrose agar with chloramphenicol. The average concentrations of total fungal bio-aerosols in the hospital indoor and outdoor air were 40.48 and 119.6 CFU/m³, respectively. Onco-hematology and bone marrow transplantation wards were the most and least contaminated units, respectively (11.09 CFU/m³ vs 1.47 CFU/m³). The most common fungi isolated from the indoor environment were Penicillium spp. (45.86%) which was followed by Cladosporium spp. (31.92%), Aspergillus section Nigri (6.26%), sterilized mycelia (5.05%), and Aspergillus section Flavi (2.83%). Cladosporium spp. (61.10 CFU/m³) and Penicillium spp. (18.56 CFU/m³) had the highest mean concentrations in outdoor and indoor air, respectively. The indoor-to-outdoor ratio of fungal aerosols was < 1 at most sampling sites, indicating that the indoor fungal bio-aerosols may have originated from the outdoor environment.

Ventilation and Air Quality in Student Dormitories in China: A Case Study during Summer in Nanjing

The Air quality in student dormitories can have a major impact on the health of millions of students in China. This study aims to investigate the ventilation and air quality in student dormitories. Questionnaire survey was conducted in eight dormitory buildings and field measurements were conducted in one dormitory during the summer in Nanjing. The survey result reveals that most students thought the indoor and outdoor air quality was neutral and the correlation between indoor and outdoor perceived air quality is statistically significant. There are few indoor PM2.5 and ozone sources in dormitories and natural ventilation is the most common form of ventilation. However, there is no statistically significant correlation between window opening behaviors and the perceptions of indoor and outdoor air quality. The field measurement result shows the measured I/O ratios of PM2.5 and ozone over 37 days are in the range of 0.42⁻0.79 and 0.21⁻1.00, respectively. The I/O ratios for PM2.5 and ozone are 0.49 ± 0.05 and 0.26 ± 0.05 in the case of the window being closed, and the I/O ratios for PM2.5 and ozone are 0.65 ± 0.08 and 0.50 ± 0.15 in the case of the window being open. The outdoor and indoor ozone concentrations show pronounced diurnal periodic variations, while the PM2.5 concentrations do not. Finally, recommended open/close window strategies are discussed to reduce indoor pollutant levels. Understanding the indoor/outdoor PM2.5 and ozone concentrations in different window patterns can be a guidance to preventing high indoor PM2.5 and ozone exposure in student dormitories.

Indoor and outdoor particulate matter in primary school classrooms with fan-assisted natural ventilation in Singapore

We conducted multiday continuous monitoring of indoor and outdoor particulate matter (PM) in classrooms with fan-assisted natural ventilation (NV) at five primary schools in Singapore. We monitored size-resolved number concentration of PM with diameter 0.3-10 μm at all schools and alveolar deposited surface area concentrations of PM with diameter 0.01-1.0 μm (SA0.01-1.0) at two schools. Results show that, during the monitoring period, schools closer to expressways and in the downtown area had 2-3 times higher outdoor PM0.3-1.0 number concentrations than schools located in suburban areas. Average indoor SA0.01-1.0 was 115-118 μm(2) cm(-3) during periods of occupancy and 72-87 μm(2) cm(-3) during unoccupied periods. There were close indoor and outdoor correlations for fine PM during both occupied and unoccupied periods (Pearson's r = 0.84-1.0) while the correlations for coarse PM were weak during the occupied periods (r = 0.13-0.74). Across all the schools, the size-resolved indoor/outdoor PM ratios (I/O ratios) were 0.81 to 1.58 and 0.61 to 0.95 during occupied and unoccupied periods, respectively, and average infiltration factors were 0.64 to 0.94. Average PM net emission rates, calculated during periods of occupancy in the classrooms, were lower than or in the lower range of emission rates reported in the literature. This study also reveals that indoor fine and submicron PM predominantly come from outdoor sources, while indoor sources associated with occupancy may be important for coarse PM even when the classrooms have high air exchange rates.

Does Spore Count Matter in Fungal Allergy?: The Role of Allergenic Fungal Species

Purpose

Fungi have been known to be important aeroallergens for hundreds of years. Most studies have focused on total fungal concentration; however, the concentration of specific allergenic fungi may be more important on an individual basis.

Methods

Ten fungal allergic patients and 2 non-fungal allergic patients were enrolled. The patients with a decrease in physician or patient global assessment by more than 50% of their personal best were considered to have an exacerbation of allergic symptoms and to be in the active stage. Those who maintained their physician and patient global assessment scores at their personal best for more than 3 months were considered to be in the inactive stage. The concentrations of dominant fungi in the patients' houses and outdoors were measured by direct and viable counts at active and inactive stages.

Results

The exacerbation of allergic symptoms was not correlated with total fungal spore concentration or the indoor/outdoor ratio (I/O). Specific fungi, such as Cladosporium oxysporum (C. oxyspurum), C. cladosporioides, and Aspergillus niger (A. niger), were found to be significantly higher concentrations in the active stage than in the inactive stage. Presumed allergenic spore concentration threshold levels were 100 CFU/m³ for C. oxysporum, and 10 CFU/m³ for A. niger, Penicillium brevicompactum and Penicillium oxalicum.

Conclusions

The major factor causing exacerbation of allergic symptoms in established fungal allergic patients may be the spore concentration of specific allergenic fungi rather than the total fungal concentration. These results may be useful in making recommendations as regards environmental control for fungal allergic patients.

Quantifying the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building

Improper natural ventilation practices may deteriorate indoor air quality when in close proximity to roadways, although the intention is often to reduce energy consumption. In this study, we employed a CFD-based air quality model to quantify the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building. Our study found that the building envelope restricts dispersion and dilution of particulate matter. The indoor concentration in the baseline condition located 10m away from the roadway is roughly 16-21% greater than that at the edge of the roadway. The indoor flow recirculation creates a well-mixed zone with little variation in fine particle concentration (i.e., 253nm). For ultrafine particles (<100nm), a noticeable decrease in particle concentrations indoors with increasing distance from the road is observed due to Brownian and turbulent diffusion. In addition, the indoor concentration strongly depends on the distance between the roadway and building, particle size, wind condition, and window size and location. A break-even point is observed at D'~2.1 (normalized distance from the roadway by the width of the road). The indoor particle concentration is greater than that at the highway where D'<2.1, and vice versa. For new building planning, the distance from the roadway and the ambient wind condition need to be considered at the early design stage whereas the size and location of the window openings, the interior layout, and the placement of fresh air intakes are important to the indoor air quality of existing buildings adjacent to roadways.

Indoor and outdoor suspended particulate matter and associated carbonaceous species at residential homes in northwestern Portugal

Particulate matter with an aerodynamic diameter equal to or less than 10 μm (PM10), organic carbon (OC) and elemental carbon (EC) concentrations were measured simultaneously in the indoor and outdoor air of 4 residences located in urban and sub-urban areas in northwestern Portugal. The residences were studied with occupants. One residence was also studied without any indoor activity, taking advantage of the fact that the occupants had moved into a new home. First, 48-h aerosol samples were collected on quartz fiber filters with low-volume samplers equipped with size selective inlets. The filters were weighed and then analyzed for OC and EC using a thermal-optical transmittance method. The average indoor and outdoor PM10 concentrations in the occupied residences were 71.9 ± 38.3 μg/m(3) and 54.0 ± 13.3 μg/m(3), respectively. Despite the higher concentration of PM10 indoors, outdoor sources were found to be a significant contributor to indoor concentrations. An estimate based on data from the residence studied under different occupancy conditions indicated that outdoor sources can account for 68% of the indoor PM10 mass concentration. Average indoor to outdoor (I/O) ratios for OC ranged from 1.7 to 5.6 in occupied residences, showing that indoor sources, such as cooking, smoking, biomass burning and movement of people, strongly influenced indoor OC concentrations. In contrast, I/O ratios for EC were close to 1, except for a smokers' residence, suggesting that indoor concentrations were mainly controlled by outdoor sources, most likely from vehicular emissions and biomass burning.