Indoor air pollutant health prioritization in office buildings

This work presents an original method to identify priority indoor air pollutants in office buildings. It uses both a chronic risk assessment approach by calculating a hazard quotient, and a hazard classification method based on carcinogenic, mutagenic, reprotoxic, and endocrine disruptive effects. A graphical representation of the results provides a comprehensive and concise visualization of all of the information, including the number of buildings where each substance was measured, an indicator of exposure data robustness. Seventy-one out of 342 substances (20%) for which indoor air concentrations have already been measured in office buildings were identified as priority pollutants. The results were compared to previous prioritization studies in various types of indoor environments to assess the reliability of the method and highlight its advantages. Sensitivity analyses were performed to reduce the geographical scope (OECD countries only), time scope (after 2010 only), and measurement duration (working hours only) and showed little influence on the results. Finally, 123 additional substances that could be present in office indoor air but could not be assessed due to the lack of measurement data are proposed for future monitoring surveys to update the prioritization of indoor air pollutants in offices.     

Volatile organic pollutants in new and established buildings in Melbourne, Australia

Volatile organic compounds (VOCs) within new and established buildings have been determined and factors significant to their presence have been identified. In established dwellings, total volatile organic compound (TVOC) concentrations were low, but were approximately four times higher than in outdoor air, showing a dominant effect of indoor sources. The presence of attached garages, site contamination and 'faulty' wool carpet were associated with higher indoor pollution. In three dwellings, unidentified sources of benzene were indicated. Much higher VOC concentrations were observed in new or renovated buildings, persisting above "baseline" levels for several weeks, concentration decay rate correlating with VOC molecular volume, indicating emissions were limited by material diffusion processes. VOC and formaldehyde emission decays in a new dwelling occurred by a double-exponential source model. This shows that persistent low levels of volatile organic pollutants in established dwellings can occur due to long-term emissions from building materials.     

Überlegenheit moderner,innovativer Planungswerkzeuge in der Gebäudeplanung

Superiority of advanced, innovative design tools. In Germany, standard building design is often determined in the traditional way that is, solely according to the HOAI (Official Scale of Fees for Services by Architects and Engineers) [1]. This means that in most cases only simplistic design tools are used by default. However, with high‐class complex buildings these are not always an adequate means of ensuring that the often stringent requirements their use places on the indoor climate conditions are met once they are in operation. In ambitious buildings featuring numerous open areas inside and open exits leading outdoors or to adjacent buildings but still place stringent requirements on the indoor climate conditions, the interactions between the individual areas inside and between these and ambient air are extremely important. Such buildings often appear transparent so as to look attractive to visitors: keeping entrance doors open helps to attract the attention of passers‐by and to make the buildings seem more inviting. The resulting streams of visitors necessitate a multiple open doorways, resulting in more or less strong airflow within the buildings. The effects of this wind‐ and buoyancy‐induced airflow on the indoor climate conditions proposed for a particular building can only be evaluated by means of advanced innovative design methods in the form of simulation technology. The airflow inside the buildings raises a number of very different issues regarding their design which can only be resolved by means of different simulation techniques. Using the new entrance building (NEG) on Berlin's Museum Island as an example, typical design issues are exemplified and the corresponding simulation techniques presented here. In this way the – urgently needed – transparency concerning the application of building simulation technology is encouraged.     

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 gaseous air pollutants determinants in office buildings—The OFFICAIR project

The aim of this study was to identify determinants of aldehyde and volatile organic compound (VOC) indoor air concentrations in a sample of more than 140 office rooms, in the framework of the European OFFICAIR research project. A large field campaign was performed, which included (a) the air sampling of aldehydes and VOCs in 37 newly built or recently retrofitted office buildings across 8 European countries in summer and winter and (b) the collection of information on building and offices’ characteristics using checklists. Linear mixed models for repeated measurements were applied to identify the main factors affecting the measured concentrations of selected indoor air pollutants (IAPs). Several associations between aldehydes and VOCs concentrations and buildings’ structural characteristic or occupants’ activity patterns were identified. The aldehyde and VOC determinants in office buildings include building and furnishing materials, indoor climate characteristics (room temperature and relative humidity), the use of consumer products (eg, cleaning and personal care products, office equipment), as well as the presence of outdoor sources in the proximity of the buildings (ie, vehicular traffic). Results also showed that determinants of indoor air concentrations varied considerably among different type of pollutants.     

A case study of sub-slab depressurization for a building located over VOC-contaminated ground

A sub-slab depressurization system for protecting indoor air quality in buildings located over VOC-contaminated ground is described. Included in the design is a means of assessing the performance of the protection measures during the lifetime of the building. A case study is presented of the sub-slab depressurization system implemented in two renovated historic buildings located at the site of an old gas works facility with extensive tar and PAH contamination in the soil. Measurements of under pressure under the slab and airflow rates in the sub-floor exhaust ventilation ducts from performance checks both immediately after the systems were installed and then 2 years later demonstrated that the protection measures in each building functioned as planned. VOC measurements in indoor air in the buildings during the two performance checks suggested that the air quality in the buildings was not adversely affected by the contamination in the soil.     

Investigation of volatile organic compounds in office buildings in Bangkok,Thailand: Concentrations,sources, and occupant symptoms

To conserve energy, office buildings with air-conditioning systems in Thailand are operated with a tight thermal envelope. This leads to low fresh-air ventilation rates and is thought to be partly responsible for the sick building syndrome symptoms reported by occupants. The objectives of this study are to measure concentrations and to determine sources of 13 volatile organic compounds (VOCs) in office buildings with air-conditioning systems in the business area of Bangkok. Indoor and outdoor air samples from 17 buildings were collected on Tenax-TA^™ sorbent tubes and analyzed for individual VOCs by thermal desorption-gas chromatography/mass spectrometry (TD–GC/MS). Building ventilation was measured with a constant injection technique using hexafluorobenzene as a tracer gas. The results show that the VOC concentrations varied significantly among the studied buildings. The two most dominant VOCs were toluene and limonene with average concentrations of 110 and 60.5 μg m⁻³, respectively. A Wilcoxon sum rank test indicated that the indoor concentrations of aromatic compounds and limonene were statistically higher than outdoor concentrations at the 0.05 level, while the indoor concentrations of chlorinated compounds were not. Indoor emission factors of toluene and limonene were found to be highest with the average values of 80.9 and 18.9 μg m⁻² h⁻¹, respectively. Principal component analysis was applied to the emission factors of 13 VOCs, producing three components based on source similarities. Furthermore, a questionnaire survey investigation and field measurements of building air exchange pointed to indoor air complaints related to inadequate ventilation.     

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.     

Semi‐volatile organic compounds in heating,ventilation, and air‐conditioning filter dust in retail stores

Retail stores contain a wide range of products that can emit a variety of indoor pollutants. Among these chemicals, phthalate esters and polybrominated diphenyl ethers (PBDEs) are two important categories of semi‐volatile organic compounds (SVOCs). Filters in heating, ventilation, and air‐conditioning (HVAC) system collect particles from large volumes of air and thus potentially provide spatially and temporally integrated SVOC concentrations. This study measured six phthalate and 14 PBDE compounds in HVAC filter dust in 14 retail stores in Texas and Pennsylvania, United States. Phthalates and PBDEs were widely found in the HVAC filter dust in retail environment, indicating that they are ubiquitous indoor pollutants. The potential co‐occurrence of phthalates and PBDEs was not strong, suggesting that their indoor sources are diverse. The levels of phthalates and PBDEs measured in HVAC filter dust are comparable to concentrations found in previous investigations of settled dust in residential buildings. Significant correlations between indoor air and filter dust concentrations were found for diethyl phthalate, di‐n‐butyl phthalate, and benzyl butyl phthalate. Reasonable agreement between measurements and an equilibrium model to describe SVOC partitioning between dust and gas‐phase is achieved.     

Increasing the indoor humidity levels in buildings with ventilation systems: Simulation aided design in case of passive houses

In modern societies, people spend about 90 percent of their time inside buildings. The challenge of building physics is to ensure that buildings are planned, constructed and built to provide a comfortable and healthy working and living environment. As construction style has changed during recent years, the planning phase has to be much more precise and the need of simulation programs that respond to every little change arises. An increasing problem in Austria is the indoor humidity. In the field of renovated buildings with airtight new building envelopes, mould growth due to high indoor relative humidity (RH) is a persistent problem. On the other hand, in recently realized Austrian passive houses with an air treatment system, the low humidity level of the indoor air is a problem with which scientists have been struggling for some time. It has been observed in numerous measurements and it is also easily computationally detectable that in winter period the indoor relative humidity level often drops below 30% RH. Low and high relative humidity levels have negative effects on the comfort feeling and health of the occupants of the dwelling and should therefore be avoided. However, it is expensive to increase or decrease the humidity in houses mechanically. Therefore, the existing room moisture should be used sensibly in buildings with a ventilation system. In buildings with a high indoor humidity it is necessary to adjust the ventilation depended on moisture production. This paper focuses on low indoor humidity and presents some different methods by which the indoor relative humidity can be regulated. The effects of adapting parameters such as ventilation rate and buffering material in the dwelling were clearly reflected in the measured temperature and relative humidity. “BuildOpt_VIE” software developed at the Vienna University of Technology was used for the dynamic building simulation in this study.     

Volatile organic compounds in indoor environments in Mumbai, India

Air samples, representing different types of indoor environments, were collected and analyzed for eight hydrocarbons namely, n-hexane, benzene, heptane, toluene, p- and o-xylene, ethyl benzene and n-decane using a cryogenic preconcentration system and a gas chromatograph with a flame-ionization detector. Simultaneous outdoor samples were also collected to determine indoor to outdoor (I/O) ratios for every compound at each location. In all, seven different types of indoor environments were investigated for VOC levels. Toluene concentration levels were found to be high in a hall which was recently renovated. The indoor environment of a kitchen in which a kerosene stove was used and smoker's rooms showed high levels of benzene. The concentrations of VOCs during painting were found to be high and the levels of VOCs depended on the type of paint used. The study revealed that the indoor concentrations of selected VOCs on occasions could be significantly high due to various sources. The data presented here can be useful in developing air quality standards for indoor air.     

Concentrations of Volatile Organic Compounds in Indoor Air – A Review

A review is presented of investigations of volatile organic compound (VOC) concentrations in indoor air of buildings of different classifications (dwellings, offices, schools, hospitals) and categories (established, new and complaint buildings). Measured concentrations obtained from the published literature and from research in progress overseas were pooled so that VOC concentration profiles could be derived for each building classification/category. Mean concentrations of individual compounds in established buildings were found to be generally below 50 μg/m³, with most below 5 μg/m³. Concentrations in new buildings were much greater, often by an order of magnitude or more, and appeared to arise from construction materials and building contents. The nature of these sources and approaches to reduce indoor air concentrations by limiting source VOC emissions is discussed. Total VOC (TVOC) concentrations were substantially higher than concentrations of any individual VOCs in all situations, reflecting the large number of compounds present, but interpretation of such measurements was limited by the lack of a common definition for TVOC relevant to occupant exposure.     

Comparative monitoring of natural,hybrid and mechanical ventilation systems in urban canyons

A number of field and indoor experimental procedures were performed in three typical apartment buildings located in two street canyons characterized by different urban features, during summer period 2002 in Athens. Natural, mechanical and hybrid ventilation measurements were performed based on the tracer gas method on a circular basis within the 24-h period. The indoor exchange rates are estimated using both single and multi-zone approaches based on the mass balance of two tracer gases (N₂O and SF₆). The experiments pointed out that, in spite of the canyon effect, appreciable ventilation rates can be obtained with natural ventilation, especially when cross ventilation with two or more windows is measured. In the presence of cross ventilation and with sufficient ambient wind speeds, natural ventilation is shown to be more effective, with regard to ACH, in comparison with hybrid. However, when only single-sided ventilation is possible or under calm conditions hybrid ventilation has a slight advantage over natural. A comparative analysis is made for the total air change rates estimated with the single and multi-zone methodologies. The multi-zone approach, in spite of its better theoretical basis, has been found more sensitive to the accuracy of the measured concentrations, especially when a single tracer is used.     

Outdoor Air Contaminants and Indoor Air Quality under Transient Conditions

The indoor concentrations of contaminants originating from outdoor sources have been measured and calculated under transient conditions. The results show that contaminants that are supplied to an office building via the ventilation system can reach considerably high concentration levels. The indoor/outdoor concentration ratio and time lag are dependent on the air change rate. In buildings with low air change rates the indoor concentration variations are smoothed out compared to buildings with high air change rates. The results from the theoretical model are compared to the results from both laboratory and field measurements and the model is verified for well mixed conditions in a 20 m³ test chamber. The model can be used to simulate different control strategies for reduction of indoor contaminant concentrations related to outdoor sources. One such control strategy is based on reduction of the outdoor air change rate during periods with peak outdoor contaminant concentrations.     

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).     

The effect of reduction measures on concentrations of hazardous semivolatile organic compounds in indoor air and dust of Swedish preschools

Young children spend a substantial part of their waking time in preschools. It is therefore important to reduce the load of hazardous semivolatile organic compounds (SVOCs) in the preschools’ indoor environment. The presence and levels of five SVOC groups were evaluated (1) in a newly built preschool, (2) before and after renovation of a preschool, and (3) in a preschool where SVOC-containing articles were removed. The new building and the renovation were performed using construction materials that were approved with respect to content of restricted chemicals. SVOC substance groups were measured in indoor air and settled dust and included phthalates and alternative plasticizers, organophosphate esters (OPEs), brominated flame retardants, and bisphenols. The most abundant substance groups in both indoor air and dust were phthalates and alternative plasticizers and OPEs. SVOC concentrations were lower or of the same order of magnitude as those reported in comparable studies. The relative Cumulative Hazard Quotient (HQ_cum) was used to assess the effects of the different reduction measures on children's SVOC exposure from indoor air and dust in the preschools. HQ_cum values were low (1.0–6.1%) in all three preschools and decreased further after renovation and article substitution. The SVOCs concentrations decreased significantly more in the preschool renovated with the approved building materials than in the preschool where the SVOC-containing articles were removed.     

Location of air intakes to avoid contamination of indoor air: a wind tunnel investigation

The location of air intakes is of prime importance in buildings that are situated in close proximity to busy urban roads. If intakes are placed where the concentration of traffic pollution is high then indoor air concentrations can reach similarly high levels. This paper presents the findings from a wind tunnel investigation into the dispersion of a simulated traffic pollutant in a 1:100 scale model. The concentrations at different points on a building in the model are measured and a comparison with full-scale data is made.     

Carbonyl levels in indoor and outdoor air in Mexico City and Xalapa,Mexico

Carbonyl compounds in air were measured at two houses, three museums, and two offices. All sites lacked air-conditioning systems. Although indoor and outdoor air was measured simultaneously at each site, the sites themselves were sampled in different dates. Mean concentrations were higher in indoor air. Outdoor means concentrations of acetone were the highest in all sites, ranging from 12 to 60 microg m(-3). In general, formaldehyde and acetaldehyde had similar mean concentrations, ranging from 4 to 32 and 6 to 28 microg m(-3), respectively. Formaldehyde and acetone mean indoor concentrations were the highest, ranging from 11 to 97 and 17 to 89 microg m(-3), respectively, followed by acetaldehyde with 5 to 47 microg m(-3). Formaldehyde and acetaldehyde had the highest mean concentration in the offices where there were smokers. Propionaldehyde and butyraldehyde concentrations did not show definite differences between indoor and outdoor air. In general, the highest outdoor and indoor hourly concentrations were observed from 10:00 to 15:00 h. Mean indoor/outdoor ratios of carbonyls exceeded 1. Formaldehyde and acetaldehyde risks were higher in smoking environments.     

Emissions of VOCs,SVOCs, and mold during the construction process: Contribution to indoor air quality and future occupants’ exposure

Building materials and human activities are important sources of contamination indoors, but little information is available regarding contamination during construction process which could persist during the whole life of buildings. In this study, six construction stages on two construction sites were investigated regarding the emissions of 43 volatile organic compounds (VOCs), 46 semi-volatile organic compounds (SVOCs), and the presence of 4 genera of mold. Results show that the future indoor air quality does not only depend on the emissions of each building product but that it is also closely related to the whole implementation process. Mold spore measurements can reach 1400 CFU/m³, which is particularly high compared with the concentrations usually measured in indoor environments. Relatively low concentrations of VOCs were observed, in relation to the use of low emissive materials. Among SVOCs analyzed, some phthalates, permethrin, and hydrocarbons were found in significant concentrations upon the delivery of building as well as triclosan, suspected to be endocrine disruptor, and yet prohibited in the treatment of materials and construction since 2014. As some regulations exist for VOC emissions, it is necessary to implement them for SVOCs due to their toxicity.     

Modeling volatile organic compound (VOC) concentrations due to material emissions in a real residential unit. Part I: Methodology and a preliminary case study

High volatile organic compound (VOC) concentrations following building decoration have been observed frequently. In reality, however, residents do not know the indoor VOC concentration levels until the buildings are tested, which seldom provides a preventive measure. While several indoor air quality (IAQ) simulation programs have been developed to predict indoor contaminant levels, case studies in the literature are scarce regarding the predictability of indoor VOC concentrations as well as how such predictions could be performed in real buildings. In this paper, we intended to conduct a proof-of-concept study whether simulations can help to reveal some of the key features of VOC concentrations during indoor decoration process. We conducted a case study, simulated and measured the VOC concentrations of a residential unit during the room decoration process. Results show that while certain agreement was achieved between the measurement and simulation, application of IAQ models to real buildings is challenging under the best of circumstances—single zone spaces with very few emission materials inside.