Emission of ammonia from indoor concrete wall and assessment of human exposure

Addition of urea-based antifreeze admixtures during cement mixing can make it possible to produce concrete cement in construction of buildings in cold weather; this, however, has led to increasing indoor air pollution due to continuous transformation and emission from urea to gaseous ammonia in indoor concrete wall. It is believed that ammonia is harmful to human body and exposure to ammonia can cause some serious symptoms such as headaches, burns, and even permanent damage to the eyes and lungs. In order to understand the emission of ammonia from indoor concrete wall in civil building and assess the health risk of people living in these buildings, the experimental pieces of concrete wall were first prepared by concreting cement and urea-based antifreeze admixtures to simulate the indoor wall in civil building in this work. Then environmental chamber was adopted for studying the effect of temperature, relative humility and air exchange rate on emission of ammonia from experimental pieces of concrete wall. Also the field experiment was made at selected rooms in given civil buildings. Exposure and potential dose of adult and children exposed to indoor/outdoor ammonia in summer and in winter are calculated and evaluated by using Scenario Evaluation Approach. The results indicated that high air exchange rate leads to decreased ammonia concentration, and elevation of temperature causes increasing ammonia concentration and volatilizing rate in chamber. The complete emission of ammonia from the wall containing urea-based antifreeze admixtures needs more than 10 years in general. Ventilating or improving air exchange can play a significant role in reducing ammonia concentration in actual rooms in field experiments. Urea-based antifreeze admixtures in concrete wall can give rise to high exposure and potential dose, especially in summer. Generally, adults have a high potential dose than children, while children have personal average dose rate beyond adults in the same conditions.     

Indoor air pollution due to organic gases and vapours of solvents in building materials

The emission of organic gases and vapours of solvent type from 42 commonly used building materials was measured under standard atmospheric conditions. An average of 22 compounds was found in the air around each building material, and the total concentration of gases and vapours was from 0.01 to 1410 mg/m³. The average arithmetic emission rate was 9.5 mg/m² h, and 52 different compounds were identified. A mathematical model was established for the indoor air concentrations of pollutants originating from building materials. The model was tested on three model rooms constructed from the materials investigated. The calculated total air concentrations of gases and vapours in the three rooms ranged from 1.6 to 23.6 mg/m³, and the number of compounds in the air from 23 to 32. These concentrations and number of compounds did not differ from those found in actual rooms similar in size and construction to the model rooms. The risks of health effects due to the compounds identified from the building materials were investigated, and criteria for future air quality standards are discussed. It is concluded that the possibility of negative health effects cannot be neglected, especially not for the more sensitive minority of the general population.     

Indoor climate in low-ventilated day-care institutions

Measurements of indoor atmospheric environment were carried out in a day nursery and a kindergarten, in which natural air infiltration supplied the rooms with only 1–2 m³ fresh air per person and hour under the prescribed occupancy. The exposure situation from the field was duplicated under controlled conditions in a climate chamber. The results indicate unacceptably high concentrations of carbon dioxide, and emphasize the need for more elaborate building design in airtight buildings.     

Inflammatory markers in relation to long-term air pollution

Long-term exposure to ambient air pollution can lead to chronic health effects such as cancer, cardiovascular and respiratory disease. Systemic inflammation has been hypothesized as a putative biological mechanism contributing to these adverse health effects. We evaluated the effect of long-term exposure to air pollution on blood markers of systemic inflammation.We measured a panel of 28 inflammatory markers in peripheral blood samples from 587 individuals that were biobanked as part of a prospective study. Participants were from Varese and Turin (Italy) and Umea (Sweden). Long-term air pollution estimates of nitrogen oxides (NO_x) were available from the European Study of Cohorts for Air Pollution Effects (ESCAPE). Linear mixed models adjusted for potential confounders were applied to assess the association between NO_x and the markers of inflammation.Long-term exposure to NO_x was associated with decreased levels of interleukin (IL)-2, IL-8, IL-10 and tumor necrosis factor-α in Italy, but not in Sweden. NO_x exposure levels were considerably lower in Sweden than in Italy (Sweden: median (5th, 95th percentiles) 6.65 μg/m³ (4.8, 19.7); Italy: median (5th, 95th percentiles) 94.2 μg/m³ (7.8, 124.5)). Combining data from Italy and Sweden we only observed a significant association between long-term exposure to NO_x and decreased levels of circulating IL-8.We observed some indication for perturbations in the inflammatory markers due to long-term exposure to NO_x. Effects were stronger in Italy than in Sweden, potentially reflecting the difference in air pollution levels between the two cohorts.     

Emissions from indoor dust inhibit proliferation of A549 cells and TNFalpha release from stimulated PBMCs

Dust accumulating on hot indoor surfaces, e.g., heaters and light fixtures, are likely to emit chemicals when heated. Using in vitro techniques we have investigated biological effects of extracts from such emissions from three indoor and two outdoor dust samples heated at 50-250 degrees C. The cell cultures were a lung epithelial cell line (A549) and primary immune cells [peripheral blood mononuclear cell (PBMCs)]. We found that a 24-h incubation with extracts generated at 200 degrees C or higher inhibit both proliferation and mitochondrial activity of the epithelial cells. At non-cytotoxic concentrations, the extracts generated at 100 degrees C or higher inhibit the release of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) from lipopolysaccharide-stimulated PBMCs. The results imply that temperatures relevant for surfaces of equipment in the indoor environment cause emissions from dust that may have an impact on indoor air quality and affect the respiratory health of building occupants.     

Flame retardants in indoor dust and air of a hotel in Japan

Occurrence of flame retardants (FRs) in the indoor environment of highly flame-retarded public facilities is an important concern from the viewpoint of exposure because it is likely that FRs are used to a greater degree in these facilities than in homes. For this study, brominated flame-retardants (BFRs) and organophosphate flame-retardants and plasticizers (OPs), and brominated dibenzo-p-dioxins/furans (PBDD/DFs) were measured in eight floor dust samples taken from a Japanese commercial hotel that was assumed to have many flame-retardant materials. Concentrations of polybrominated diphenylethers (PBDEs) and hexabromocyclododecanes (HBCDs) varied by about two orders of magnitude, from 9.8–1700 ng/g (median of 1200 ng/g) and from 72–1300 ng/g (median of 740 ng/g), respectively. Concentrations of the two types of BFRs described above were most dominant among the investigated BFRs in the dust samples. It is inferred that BFR and PBDD/DF concentrations are on the same level as those in house and office dust samples reported based on past studies. Regarding concentrations of 11 OPs, 7 OPs were detected on the order of micrograms per gram, which are equivalent to or exceed the BFR concentrations such as PBDEs and HBCDs. Concentrations of the investigated compounds were not uniform among dust samples collected throughout the hotel: concentrations differed among floors, suggesting that localization of source products is associated with FR concentrations in dust. Passive air sampling was also conducted to monitor BFRs in the indoor air of hotel rooms: the performance of an air cleaner placed in the room was evaluated in terms of reducing airborne BFR concentrations. Monitoring results suggest that operation of an appropriate air cleaner can reduce both gaseous and particulate BFRs in indoor air.     

Ventilation for control of indoor air quality: A case study

Dilution of indoor air contaminants with less contaminated outdoor air is the most common strategy for control of indoor air quality. Unfortunately this strategy frequently imposes a substantial energy burden. If the contaminants are associated with occupants and their activities, a ventilation control system based on the carbon dioxide level in the controlled space is shown to relieve this energy burden. A test was carried out in the Fridley, MN, Junior High School Music Department to obtain air quality, energy, and subjective response data on an Automatic Variable Ventilation System. A control system with both CO₂ and temperature inputs was devised to control the use of outdoor air. Infiltration measurements lead to a quantitative measure of ventil3tion efficiency. This in turn led to recommendations for air circulation patterns in rooms. The measured ventilation efficiency enabled energy and CO₂ models to fit measured data. Energy savings of approximately 20% were found for this application. Subjective response of the occupants also was measured. A special questionnaire, subjected to statistical analysis, showed that the subjects felt warmer with increased CO₂ in the room air.     

Volatile organic compounds in indoor environment and photocatalytic oxidation: state of the art

Volatile organic compounds (VOCs) are the major pollutants in indoor air, which significantly impact indoor air quality and thus influencing human health. A long-term exposure to VOCs will be detrimental to human health causing sick building syndrome (SBS). Photocatalytic oxidation of VOCs is a cost-effective technology for VOCs removal compared with adsorption, biofiltration, or thermal catalysis. In this paper, we review the current exposure level of VOCs in various indoor environment and state of the art technology for photocatalytic oxidation of VOCs from indoor air. The concentrations and emission rates of commonly occurring VOCs in indoor air are presented. The effective catalyst systems, under UV and visible light, are discussed and the kinetics of photocatalytic oxidation is also presented.     

Detection of fluorotelomer alcohols in indoor environments and their relevance for human exposure

Fluorotelomer alcohols (FTOH) are important precursors of perfluorinated carboxylic acids (PFCA). These neutral and volatile compounds are frequently found in indoor air and may contribute to the overall human exposure to per- and polyfluorinated alkyl substances (PFAS). In this study air samples of ten workplace environments and a car interior were analysed. In addition, extracts and emissions from selected outdoor textiles were analysed in order to establish their potential contribution to the indoor levels of the above-mentioned compounds.Concentrations of FTOHs measured in air ranged from 0.15 to 46.8, 0.25 to 286, and 0.11 to 57.5 ng/m³ for 6:2, 8:2 and 10:2 FTOHs, respectively. The highest concentrations in air were identified in shops selling outdoor clothing, indicating outdoor textiles to be a relevant source of FTOH in indoor workplace environments. Total amounts of FTOH in materials of outdoor textiles accounted for < 0.8–7.6, 12.1–180.9 and 4.65–105.7 μg/dm² for 6:2, 8:2 and 10:2 FTOHs, respectively. Emission from selected textiles revealed emission rates of up to 494 ng/h.The measured data show that a) FTOHs are present in indoor textiles (e.g. carpets), b) they are released at ambient temperatures and c) indoor air of shops selling outdoor textiles contains the highest levels of FTOH. Exposure of humans to perfluorooctanoic acid (PFOA) through absorption of FTOH and subsequent degradation is discussed on the basis of indoor air levels. Calculation of indoor air-related exposure using the median of the measured air levels revealed that exposure is on the same order of magnitude as the recently reported dietary intakes for a background-exposed population. On the basis of the 95th percentile, indoor air exposure to PFOA was estimated to exceed dietary exposure. However, indoor air-related intakes of FTOH are far below the tolerable daily intake (TDI) of PFOA, indicating that there is no risk to health, even when assuming an unrealistic complete degradation of FTOH into PFOA.     

Critical factors in assessing exposure to PBDEs via house dust

Assessment of indoor exposure to polybrominated diphenyl ethers (PBDEs) requires a critical examination of methods that may influence exposure estimates and comparisons between studies. We measured PBDEs in residential dust collected from 20 homes in Boston, MA, to examine 5 key questions: 1) Does the choice of dust exposure metric-e.g., concentration (ng/g) or dust loading (ng/m2)-affect analysis and results? 2) To what degree do dust concentrations change over time? 3) Do dust concentrations vary between rooms? 4) Is the home vacuum bag an acceptable surrogate for researcher-collected dust? 5) Are air and dust concentrations correlated for the same room? We used linear mixed-effects models to analyze the data while accounting for within-home and within-room correlations. We found that PBDE dust concentration and surface loading were highly correlated (r=0.86-0.95, p<0.001). Average dust concentrations did not significantly differ over an 8-month period, possibly because home furnishings changed little over this time. We observed significant differences between rooms in the same home: PBDE concentrations in the main living area were 97% higher than the bedroom for decaBDE (p=0.02) and 72% higher for pentaBDE (p=0.05). Home vacuum bag dust concentrations were significantly lower than researcher-collected dust and not strongly correlated. Air (vapor and particulate phase) and dust concentrations were correlated for pentaBDE (p=0.62, p<0.01), but not for decaBDE (p=0.25). In addition, potential markers of BDE 209 debromination (BDE 202 and the BDE197:BDE201 ratio) were also observed in household dust samples. One vacuum bag sample contained the highest concentrations of BDE 209 (527,000 ng/g) and total PBDEs (544,000 ng/g) that have been reported in house dust.     

Impact of climate change on the domestic indoor environment and associated health risks in the UK

There is growing evidence that projected climate change has the potential to significantly affect public health. In the UK, much of this impact is likely to arise by amplifying existing risks related to heat exposure, flooding, and chemical and biological contamination in buildings. Identifying the health effects of climate change on the indoor environment, and risks and opportunities related to climate change adaptation and mitigation, can help protect public health.We explored a range of health risks in the domestic indoor environment related to climate change, as well as the potential health benefits and unintended harmful effects of climate change mitigation and adaptation policies in the UK housing sector. We reviewed relevant scientific literature, focusing on housing-related health effects in the UK likely to arise through either direct or indirect mechanisms of climate change or mitigation and adaptation measures in the built environment. We considered the following categories of effect: (i) indoor temperatures, (ii) indoor air quality, (iii) indoor allergens and infections, and (iv) flood damage and water contamination.Climate change may exacerbate health risks and inequalities across these categories and in a variety of ways, if adequate adaptation measures are not taken. Certain changes to the indoor environment can affect indoor air quality or promote the growth and propagation of pathogenic organisms. Measures aimed at reducing greenhouse gas emissions have the potential for ancillary public health benefits including reductions in health burdens related heat and cold, indoor exposure to air pollution derived from outdoor sources, and mould growth. However, increasing airtightness of dwellings in pursuit of energy efficiency could also have negative effects by increasing concentrations of pollutants (such as PM_2.5, CO and radon) derived from indoor or ground sources, and biological contamination. These effects can largely be ameliorated by mechanical ventilation with heat recovery (MVHR) and air filtration, where such solution is feasible and when the system is properly installed, operated and maintained. Groups at high risk of these adverse health effects include the elderly (especially those living on their own), individuals with pre-existing illnesses, people living in overcrowded accommodation, and the socioeconomically deprived.A better understanding of how current and emerging building infrastructure design, construction, and materials may affect health in the context of climate change and mitigation and adaptation measures is needed in the UK and other high income countries. Long-term, energy efficient building design interventions, ensuring adequate ventilation, need to be promoted.     

Chlorinated paraffins in indoor air and dust: concentrations, congener patterns, and human exposure

Chlorinated paraffins (CPs) are large production volume chemicals used in a wide variety of commercial applications. They are ubiquitous in the environment and humans. Human exposure via the indoor environment has, however, been barely investigated. In the present study 44 indoor air and six dust samples from apartments in Stockholm, Sweden, were analyzed for CPs, and indoor air concentrations are reported for the first time. The sumCP concentration (short chain CPs (SCCPs) and medium chain CPs (MCCPs)) in air ranged from <5-210 ng m(-3) as quantified by gas chromatography coupled to electron ionization tandem mass spectrometry (GC/EI-MS/MS). Congener group patterns were studied using GC with electron capture negative ionization MS (GC/ECNI-MS). The air samples were dominated by the more volatile SCCPs compared to MCCPs. SumCPs were quantified by GC/EI-MS/MS in the dust samples at low μg g(-1) levels, with a chromatographic pattern suggesting the prevalence of longer chain CPs compared to air. The median exposure to sumCPs via the indoor environment was estimated to be ~1 μg day(-1) for both adults and toddlers. Adult exposure was dominated by inhalation, while dust ingestion was suggested to be more important for toddlers. Comparing these results to literature data on dietary intake indicates that human exposure to CPs from the indoor environment is not negligible.     

Emission modelling and validation of VOCs' source strengths in air-conditioned office premises

An emission model for indoor volatile organic compounds (VOCs) based on mass balance considerations has been presented and validated under steady state conditions. Comparison were made for the measured and predicted concentrations of 37 selected VOCs and TVOC through a case intervention study on the filters of the ventilation system in a new commercial air-conditioned office building. The intervention involved replacing media filters with electronic and carbon filtration. TVOC and 37 compounds selected for their health and comfort impact, representation of major chemical classes that occur in indoor air and their utility as markers of pollution sources were studied. The concentration levels predicted by the model were compared with actual measurements. Twenty-five target compounds and the TVOC were adequately described by the model where the measured concentrations were in agreement with the predicted concentrations. Modeling of the remaining 12 compounds was found to be affected by the emission rates that were occupant related.     

Children's well-being at schools: Impact of climatic conditions and air pollution

Human civilization is currently facing two particular challenges: population growth with a strong trend towards urbanization and climate change. The latter is now no longer seriously questioned. The primary concern is to limit anthropogenic climate change and to adapt our societies to its effects. Schools are a key part of the structure of our societies. If future generations are to take control of the manifold global problems, we have to offer our children the best possible infrastructure for their education: not only in terms of the didactic concepts, but also with regard to the climatic conditions in the school environment. Between the ages of 6 and 19, children spend up to 8 h a day in classrooms. The conditions are, however, often inacceptable and regardless of the geographic situation, all the current studies report similar problems: classrooms being too small for the high number of school children, poor ventilation concepts, considerable outdoor air pollution and strong sources of indoor air pollution.There have been discussions about a beneficial and healthy air quality in classrooms for many years now and in recent years extensive studies have been carried out worldwide. The problems have been clearly outlined on a scientific level and there are prudent and feasible concepts to improve the situation. The growing number of publications also highlights the importance of this subject. High carbon dioxide concentrations in classrooms, which indicate poor ventilation conditions, and the increasing particle matter in urban outdoor air have, in particular, been identified as primary causes of poor indoor air quality in schools. Despite this, the conditions in most schools continue to be in need of improvement. There are many reasons for this. In some cases, the local administrative bodies do not have the budgets required to address such concerns, in other cases regulations and laws stand in contradiction to the demands for better indoor air quality, and sometimes the problems are simply ignored.This review summarizes the current results and knowledge gained from the scientific literature on air quality in classrooms. Possible scenarios for the future are discussed and guideline values proposed which can serve to help authorities, government organizations and commissions improve the situation on a global level.     

Contribution of (222)Rn-bearing water to indoor radon and indoor air quality assessment in hot spring hotels of Guangdong, China

This study investigates the contribution of radon (²²²Rn)-bearing water to indoor ²²²Rn in thermal baths. The ²²²Rn concentrations in air were monitored in the bathroom and the bedroom. Particulate matter (PM, both PM₁₀ and PM_2.5) and carbon dioxide (CO₂) were also monitored with portable analyzers. The bathrooms were supplied with hot spring water containing 66-260 kBq m⁻³ of ²²²Rn. The results show that the spray of hot spring water from the bath spouts is the dominant mechanism by which ²²²Rn is released into the air of the bathroom, and then it diffuses into the bedroom. Average ²²²Rn level was 110-410% higher in the bedrooms and 510-1200% higher in the bathrooms compared to the corresponding average levels when there was no use of hot spring water. The indoor ²²²Rn levels were influenced by the ²²²Rn concentrations in the hot spring water and the bathing times. The average ²²²Rn transfer coefficients from water to air were 6.2 × 10⁻⁴-4.1 × 10⁻³. The 24-h average levels of CO₂ and PM₁₀ in the hotel rooms were 89% and 22% higher than the present Indoor Air Quality (IAQ) standard of China. The main particle pollutant in the hotel rooms was PM_2.5. Radon and PM₁₀ levels in some hotel rooms were at much higher concentrations than guideline levels, and thus the potential health risks to tourists and especially to the hotel workers should be of great concern, and measures should be taken to lower inhalation exposure to these air pollutants.     

Indoor air pollution and public policy

In recent years, scientist have come to realize that contaminated air inside buildings is a major route of human exposure to certain air pollutants. While scientific interest in the problem continues to grow, efforts to measure indoor pollution concentrations, define exposure levels, and estimate health risks remain in their infancy. Within this arena, policymakers must deal with the question of how best to protect public health and safety in the face of incomplete and often contradictory information. In the past, official response to environmental pollution has traditionally taken the form of “control by regulation.” However, creation of a regulatory framework for indoor air quality poses special policy issues that suggest the need to explore alternative modes of intervention. Ambient outdoor air is a public good, in the sense that enjoyment by one individual in no way detracts from use or enjoyment by others. Indoor air, on the other hand, is not a public good, especially in private residences. Costs and benefits of maintaining adequate indoor air quality are internalized within households, suggesting the possibility of a private demand for clean indoor air. Promulgation of indoor air quality standards and other regulations must confront the fact that individuals are already making decisions about their own air quality. Regulations might or might not improve these decisions. Development of effective and reasonable policy requires an appreciation of the scope for private action and consideration of the likelihood that public intervention will foster improved private choices. Among the logical and relatively inexpensive modes of intervention are public information programs, development of simple warning devices, and product testing and labeling.     

基于体感温度的中国供暖需求分区

冬季,中国北方通过集中供暖提高室内温度,而非集中供暖的南方部分地区室内阴冷,对于供暖的需求日益显现。针对仅以空气温度为依据划分的现有中国供暖区与实际人体供暖需求不一致的问题,利用1971～2010年全国740个气象站点旬气候资料,基于综合空气温度和空气湿度的体感温度模型,分析了体感温度的空间分布格局,重新界定了公里级的中国供暖需求分区。分区结果显示供暖需求高的区域(最高需求区及高需求区)面积比现有的集中供暖区大,增加的供暖需求高的地区主要位于长江中下游地区。新的供暖需求分区结果考虑了空气湿度的影响,与现有的仅考虑空气温度的供暖分区相比,更接近人体对室内冷热程度的直观感受,这可以为我国不同地区制定冬季采暖政策提供科学依据。     

Methods for control of indoor air quality

This report presents results of a review of available methods for control of environmental hazards applied to indoor air pollutants. Indoor air pollution originates from transport of ambient outdoor air contaminants into occupied spaces by natural infiltration ventilation, or by mechanical ventilation using outdoor makeup air, plus contributions from indoor emission sources. When air exchange with the external ambient environment is reduced to conserve energy, contributions from indoor emission sources may dominate indoor air pollutant levels. This paper identifies alternative methods available to control indoor air pollutant exposures. The performance characteristics of ventilation systems and of air cleaning devices used in mixed modes for ventilation of occupied spaces are described. Models for predicting effectiveness of several alternative modes are reviewed, with field trial validation results cited where available. Results of previous confined-space studies are briefly reviewed as points of departure for consideration of necessary air quality, ventilation, and air cleaning. Understanding of indoor air contaminant generation and controls is aided by examination of earlier studies of indoor air quality, using modern perspectives on occupational environmental health and hygiene.     

Within-room and within-building temporal and spatial variations in concentrations of polybrominated diphenyl ethers (PBDEs) in indoor dust

Within-house and within-room spatial temporal variability in PBDE contamination of indoor dust may influence substantially the reliability of human exposure assessments based on single point samples, but have hitherto been little studied. This paper reports concentrations of PBDEs 17, 28, 47, 49, 66, 85, 99, 100, 153, and 154 in indoor dust samples (n = 112) from two houses in Birmingham, UK. To evaluate within-house spatial variability, four separate rooms were sampled in house 1 and two separate rooms sampled in house 2. Up to four different 1 m² areas in the same room were sampled to evaluate within-room spatial variability, and for all studied areas, samples were taken for eight consecutive months to evaluate temporal and seasonal variability. Concentrations of ΣPBDEs in individual samples from house 1 varied between 21 and 280 ng g^− 1; while the range of concentrations in house 2 was 20–1000 ng g^− 1. This indicates that where and when a sample is taken in a house can influence substantially the contamination detected. In one room, concentrations of PBDEs in an area located close to putative PBDE sources exceeded substantially those in an area 2 m away, with marked differences also observed between two areas in another room. Substantial within-room spatial differences in PBDE concentrations were not discernible in the other rooms studied. Concentrations of PBDEs in the majority of rooms within the same houses were not markedly different between rooms. Nevertheless, large differences were observed between PBDE concentrations detected in two rooms in the same house in both houses studied. In one instance, this is hypothesised to be attributable to the presence of a carpet in one room and bare wooden floor in another, but firm conclusions cannot be drawn. Within-room temporal (month-to-month) variability was substantial (relative standard deviations for ΣPBDEs = 15–200%). In some rooms, the introduction and removal of putative sources like a TV and a bed, appeared to exert a discernible influence on PBDE concentrations. PBDE concentrations in spring and summer were not markedly different from those observed in autumn and winter. Possible dilution of PBDE concentrations in dust at higher dust loadings (g dust per m² floor surface) was investigated in a small number of rooms, but no firm evidence of such dilution was evident.     

Studies on indoor air quality in Egypt

Indoor air quality was examined for some gaseous pollutants and particulate matters. In a public library, the indoor/outdoor ratio of gaseous pollutants were found to be dependent on their reactivity, also on the outdoor concentrations and weather conditions. This ratio was 0.6 for SO₂,and 1.3 for CO. The indoor/outdoor ratio of carbon monoxide was found to increase at the higher floors of the same building. Concentrations of indoor particulates was found to be influenced by the outdoor concentrations and the particle size. Analysis indicated that indoor suspended dust contained a significant high concentration of lead as compared with outdoor values. Indoor sources were found to pollute the premises of fossil-fuel equipped homes, thus having carbon monoxide concentrations more than the recognized threshold limit value for industry.