Indoor air quality in ice skating rinks in Hong Kong

Indoor air quality in ice skating rinks has become a public concern due to the use of propane- or gasoline-powered ice resurfacers and edgers. In this study, the indoor air quality in three ice rinks with different volumes and resurfacer power sources (propane and gasoline) was monitored during usual operating hours. The measurements included continuous recording of carbon monoxide (CO), carbon dioxide (CO(2)), total volatile organic compounds (TVOC), particulate matter with a diameter less than 2.5 microm (PM(2.5)), particulate matter with diameter less than 10 microm (PM(10)), nitric oxide (NO), nitrogen dioxide (NO(2)), nitrogen oxide (NO(x)), and sulfur dioxide (SO(2)). The average CO, CO(2), and TVOC concentrations ranged from 3190 to 6749 microg/m(3), 851 to 1329 ppm, and 550 to 765 microg/m(3), respectively. The average NO and NO(2) concentrations ranged from 69 to 1006 microg/m(3) and 58 to 242 microg/m(3), respectively. The highest CO and TVOC levels were observed in the ice rink which a gasoline-fueled resurfacer was used. The highest NO and NO(2) levels were recorded in the ice rink with propane-fueled ice resurfacers. The air quality parameters of PM(2.5), PM(10), and SO(2) were fully acceptable in these ice rinks according to HKIAQO standards. Overall, ice resurfacers with combustion engines cause indoor air pollution in ice rinks in Hong Kong. This conclusion is similar to those of previous studies in Europe and North America.     

Indoor air pollution and acute lower respiratory infections in the first two years of life

The relationship between outdoor air pollution and acute respiratory infections (ARI) was previously documented. There are recent indications for connection between indoor air pollution and ARI in infants and young children. The aim of this study was to identify the relationship of indoor air pollutants to acute lower respiratory infection (ALRI) in children (< 2 years). The indoor air pollutants concentrations were measured in the homes of the sample. The sample consisted of 115 children (< 2 years) representing the control group (24), ALRI but no pneumonia (24), pneumonia (30), severe pneumonia or very severe disease (37). Air sampling was performed to measure the concentration of total suspended particulates (TSP), SO2 and CO. These pollutants were found in higher concentrations in cases' homes (52.46 +/- 19.68 microg/m3, 298.15 +/- 669.37 microg/m3, and 1.92 +/- 3.60 ppm) than in controls' homes (31.92 +/- 8.76 microg/m3, not detected, and 0.33 +/- 1.63 ppm respectively). Whereas SO2 was detected only in houses using kerosene, TSP and CO were detected with the different types of cooking fuels. Their mean concentrations were highest for biomass (88.86 +/- 13.30 microg/m3 and 9.29 +/- 2.50 ppm) and lowest for gas (40.78 +/- 15.25 microg/m3 and 0.76 +/- 2.19 ppm). Measures to improve indoor air quality are highly required.     

2007—2011年中山市新装修家居和办公场所室内空气质量分析

目的了解广东省中山市室内新装修家居和办公场所空气质量。方法统计分析中山市2007—2011年监测的179户、1 269个监测点的家居和办公场所监测数据,监测指标包括甲醛、苯、甲苯、二甲苯和总挥发性有机化合物(TVOCs),对其进行空气质量指数分析。结果甲醛、苯、甲苯、二甲苯和TVOCs的最高浓度分别为1.48 mg/m3、117.52 mg/m3、21.68 mg/m3、0.73 mg/m3和10.3 mg/m3;家居场所的甲醛、甲苯和二甲苯浓度合格率显著低于办公场所(χ2=83.51,P=0.000;χ2=86.15,P=0.000;χ2=64.68,P=0.000);家居场所和办公场所的室内空气质量指数平均秩次分别为844.94和570.00,办公场所的室内空气质量优于家居场所(Z=-13.799,P<0.001)。结论新装修场所有机物污染程度参差不齐,甲醛是首要的室内空气污染物,家居场所是室内空气污染的高风险场所,应对重点污染物和重点场所加强预防控制。     

Characterization of indoor particle sources: A study conducted in the metropolitan Boston area

An intensive particle monitoring study was conducted in homes in the Boston, Massachusetts, area during the winter and summer of 1996 in an effort to characterize sources of indoor particles. As part of this study, continuous particle size and mass concentration data were collected in four single-family homes, with each home monitored for one or two 6-day periods. Additionally, housing activity and air exchange rate data were collected. Cooking, cleaning, and the movement of people were identified as the most important indoor particle sources in these homes. These sources contributed significantly both to indoor concentrations (indoor-outdoor ratios varied between 2 and 33) and to altered indoor particle size distributions. Cooking, including broiling/baking, toasting, and barbecuing contributed primarily to particulate matter with physical diameters between 0.02 and 0.5 microm [PM((0.02-0.5))], with volume median diameters of between 0.13 and 0.25 microm. Sources of particulate matter with aerodynamic diameters between 0.7 and 10 microm [PM((0.7-10))] included sautéing, cleaning (vacuuming, dusting, and sweeping), and movement of people, with volume median diameters of between 3 and 4.3 microm. Frying was associated with particles from both PM((0.02-0.5)) and PM((0.7-10)). Air exchange rates ranged between 0.12 and 24.3 exchanges/hr and had significant impact on indoor particle levels and size distributions. Low air exchange rates (< 1 exchange/hr) resulted in longer air residence times and more time for particle concentrations from indoor sources to increase. When air exchange rates were higher (> 1 exchange/hr), the impact of indoor sources was less pronounced, as indoor particle concentrations tracked outdoor levels more closely.     

Symptoms of mothers and infants related to total volatile organic compounds in household products

The authors sought to determine whether reported symptoms of mothers and infants were associated significantly with the use of household products that raised indoor levels of total volatile organic compounds (TVOCs). Data collected from 170 homes within the Avon Longitudinal Study of Parents and Children (ALSPAC: a large birth cohort of more than 10,000) had determined which household products were associated with the highest levels of TVOCs. The latter data were collected over a period that approximated 6 mo of pregnancy and the infants' first 6 mo of life. This paper presents (a) the mothers' self-reports of the use of these products in their homes and (b) self-reported medical symptoms of mothers and infants postnatally. Higher TVOC levels were associated with air freshener and aerosol use. Infant diarrhea and earache were statistically significantly associated with air freshener use, and diarrhea and vomiting were significantly associated with aerosol use. Headache experienced by mothers 8 mo after birth was significantly associated with the use of air fresheners and aerosols; maternal depression was significantly associated with the use of air fresheners. The results of the study suggest a link between the use of products that raise indoor levels of TVOCs and an increased risk of certain symptoms among infants and their mothers.     

Influence of ambient (outdoor) sources on residential indoor and personal PM2.5 concentrations: analyses of RIOPA data

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to investigate residential indoor, outdoor and personal exposures to several classes of air pollutants, including volatile organic compounds, carbonyls and fine particles (PM2.5). Samples were collected from summer, 1999 to spring, 2001 in Houston (TX), Los Angeles (CA) and Elizabeth (NJ). Indoor, outdoor and personal PM2.5 samples were collected at 212 nonsmoking residences, 162 of which were sampled twice. Some homes were chosen due to close proximity to ambient sources of one or more target analytes, while others were farther from sources. Median indoor, outdoor and personal PM2.5 mass concentrations for these three sites were 14.4, 15.5 and 31.4 microg/m3, respectively. The contributions of ambient (outdoor) and nonambient sources to indoor and personal concentrations were quantified using a single compartment box model with measured air exchange rate and a random component superposition (RCS) statistical model. The median contribution of ambient sources to indoor PM2.5 concentrations using the mass balance approach was estimated to be 56% for all study homes (63%, 52% and 33% for California, New Jersey and Texas study homes, respectively). Reasonable variations in model assumptions alter median ambient contributions by less than 20%. The mean of the distribution of ambient contributions across study homes agreed well for the mass balance and RCS models, but the distribution was somewhat broader when calculated using the mass balance model with measured air exchange rates.     

Oxidative DNA damage estimated by urinary 8-hydroxydeoxyguanosine and indoor air pollution among non-smoking office employees

This study investigated whether urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative stress, was associated with indoor air quality for non-smokers in high-rise building offices. With informed consents, urine samples from 344 non-smoking employees in 86 offices were collected to determine 8-OHdG concentrations. The concentrations of carbon dioxide (CO(2)) and total volatile organic compounds (TVOCs) in each office and outside of the building were simultaneously measured for eight office hours. The average workday difference between indoor and outdoor CO(2) concentrations (dCO(2)) was used as a surrogate measure of the ventilation efficiency for each office unit. The CO(2) levels in the offices ranged 467-2810ppm with a mean of 1170ppm, or 2.7 times higher than that in the outside air. The average urinary 8-OHdG levels among employees increased from 3.10 micro g/g creatinine, for those at the lowest tertile levels of both dCO(2) and TVOCs, to 6.27 micro g/g creatinine, for those at the highest tertile levels. Multivariate logistic regression analysis showed that the risk of having the urinary 8-OHdG level of greater than the median, 4.53 micro g/g creatinine, for participants was increased significantly at the highest tertile dCO(2) level of >680ppm (odds ratio (OR)=3.37, 95% confidence interval (CI)=1.20-9.46). The effect was significant at the middle tertile TVOCs level of 114-360ppb (OR=2.62, 95% CI=1.43-4.79), but not at the highest tertile. Inadequate ventilation in office increases the risk of building-related oxidative stress in non-smoking employees.     

Baseline indoor air quality measurements collected from 136 metropolitan New York region commercial office buildings between 1997-1999

Between January 1997 and December 1999, 648 surveys were performed in 136 commercial office buildings in the metropolitan New York region as part of an ongoing proactive indoor environmental quality (IEQ) program. Sampling was performed on a spot basis in "nonproblem" buildings, during normal business hours, either quarterly or semiannually. Carbon dioxide (CO2), carbon monoxide (CO), and total volatile organic compounds (TVOCs) were among the various physical and gaseous parameters sampled for. More than 15,000 data points were collected, and the results were analyzed to determine the mean, median, mode, and standard deviation for each of those parameters. The data was then compared to various standards and/or guidelines applicable to the indoor environment. The results indicated that 98% of the CO2 readings were below 1000 ppm, and 99.9% of the CO readings were below 10 ppm. However, for TVOCs, nearly 88% of the readings exceeded the proposed European guideline value of 0.3 mg/m3. Ultimately, these results can be used to compare both baseline and periodic readings collected in future studies, and to help determine if potential problems exist within a building.     

Exposure to air pollutants in English homes

BRE has conducted a national representative survey of air pollutants in 876 homes in England, designed to increase knowledge of baseline pollutant levels and factors associated with high concentrations. Homes were monitored for carbon monoxide (CO), nitrogen dioxide (NO(2)), formaldehyde and volatile organic compounds (VOCs). In the majority of the homes, concentrations of the measured pollutants were low. However, some homes have concentrations that would suggest a need for precautionary mitigation. Those factors that are most likely to lead to exposures of concern in homes are identified as gas cooking (for CO and NO(2)), the use of unflued appliances for heating (for CO and NO(2)), emissions from materials in new homes (for total VOC (TVOC) and formaldehyde), and painting and decorating, with a significant increase in risk suspected to exist where there is not a place to store materials away from the living space (for TVOC). It is noteworthy that seasonal effects on CO and NO(2) were largely due to indoor sources. This would need to be considered when interpreting time series studies of the effect of outdoor air pollution on health. It is also of some significance that the critical factors are related much more to sources than to ventilation: source control is therefore, as would be expected, the most appropriate approach to reducing the risk of hazardous exposure to air pollutants in homes.     

Short-term association between ambient air pollution and risk of hospitalization for acute myocardial infarction: results of the cardiovascular risk and air pollution in Tuscany (RISCAT) study

Air pollutant levels have been widely associated with increased hospitalizations and mortality from cardiovascular disease. In this study, the authors focused on pollutant levels and triggering of acute myocardial infarction (AMI). Data on AMI hospitalizations, air quality, and meteorologic conditions were collected in 6 urban areas of Tuscany (central Italy) during 2002-2005. Levels of particulate matter with an aerodynamic diameter ≤10 μm (PM(10)) (range of 4-year mean values, 28.15-40.68 μg/m(3)), nitrogen dioxide (range, 28.52-39.72 μg/m(3)), and carbon monoxide (range, 0.86-1.28 mg/m(3)) were considered, and increases of 10 μg/m(3) (0.1 mg/m(3) for carbon monoxide) were analyzed. A time-stratified case-crossover approach was applied. Area-specific conditional regression models were fitted, adjusting for time-dependent variables. Stratified analyses and analyses in bipollutant models were performed. Pooled estimates were derived from random-effects meta-analyses. Among 11,450 AMI hospitalizations, the meta-analytical odds ratio at lag(2) (2-day lag) was 1.013 (95% confidence interval (CI): 1.000, 1.026) for PM(10), 1.022 (95% CI: 1.004, 1.041) for nitrogen dioxide, and 1.007 (95% CI: 1.002, 1.013) for carbon monoxide. More susceptible subgroups were elderly persons (age ≥75 years), females, and older patients with hypertension and chronic obstructive pulmonary disease. This study adds to evidence for a short-term association between air pollutants and AMI onset, also evident at low pollutant levels, suggesting a need to focus on more vulnerable subjects.     

Exposure to fine particles (PM2.5 and PM1) and black smoke in the general population: personal, indoor, and outdoor levels

Personal exposure to PM(2.5) and PM(1), together with indoor and residential outdoor levels, was measured in the general adult population (30 subjects, 23-51 years of age) of Gothenburg, Sweden. Simultaneously, urban background concentrations of PM(2.5) were monitored with an EPA WINS impactor. The 24-h samples were gravimetrically analyzed for mass concentration and black smoke (BS) using a smokestain reflectometer. Median levels of PM(2.5) were 8.4 microg/m(3) (personal), 8.6 microg/m(3) (indoor), 6.4 microg/m(3) (residential outdoor), and 5.6 microg/m(3) (urban background). Personal exposure to PM(1) was 5.4 microg/m(3), while PM(1) indoor and outdoor levels were 6.2 and 5.2 microg/m(3), respectively. In non-smokers, personal exposure to PM(2.5) was significantly higher than were residential outdoor levels. BS absorption coefficients were fairly similar for all microenvironments (0.4-0.5 10(-5) m(-1)). Personal exposure to particulate matter (PM) and BS was well correlated with indoor levels, and there was an acceptable agreement between personal exposure and urban background concentrations for PM(2.5) and BS(2.5) (r(s)=0.61 and 0.65, respectively). PM(1) made up a considerable amount (70-80%) of PM(2.5) in all microenvironments. Levels of BS were higher outdoors than indoors and higher during the fall compared with spring. The correlations between particle mass and BS for both PM(2.5) vs. BS(2.5) and PM(1) versus BS(1) were weak for all microenvironments including personal exposure. The urban background station provided a good estimate of residential outdoor levels of PM(2.5) and BS(2.5) within the city (r(s)=0.90 and 0.77, respectively). Outdoor levels were considerably affected by long-range transported air pollution, which was not found for personal exposure or indoor levels. The within-individual (day-to-day) variability dominated for personal exposure to both PM(2.5) and BS(2.5) in non-smokers.     

Impact of improved stoves, house construction and child location on levels of indoor air pollution exposure in young Guatemalan children

The goal of this study was to assess the impact of improved stoves, house ventilation, and child location on levels of indoor air pollution and child exposure in a rural Guatemalan population reliant on wood fuel. The study was a random sample of 204 households with children less than 18 months in a rural village in the western highlands of Guatemala. Socio-economic and household information was obtained by interview and observation. Twenty-four hour carbon monoxide (CO) was used as the primary measure of kitchen pollution and child exposure in all homes, using Gastec diffusion tubes. Twenty-four hour kitchen PM(3.5) was measured in a random sub-sample (n=29) of kitchens with co-located CO tubes. Almost 50% of the homes still used open fires, around 30% used chimney stoves (planchas) mostly from a large donor-funded programme, and the remainder of homes used various combinations including bottled gas and open fires. The 24-h kitchen CO was lowest for homes with self-purchased planchas: mean (95% CI) CO of 3.09 ppm (1.87-4.30) vs. 12.4 ppm (10.2-14.5) for open fires. The same ranking was found for child CO exposure, but with proportionately smaller differentials (P<0.0001). The 24-h kitchen PM(3.5) in the sub-sample showed similar differences (n=24, P<0.05). The predicted child PM for all 203 children (based on a regression model from the sub-sample) was 375 microg/m(3) (270-480) for self-purchased planchas and 536 microg/m(3) (488-584) for open fires. Multivariate analysis showed that stove/fuel type was the most important determinant of kitchen CO, with some effect of kitchen volume and eaves. Stove/fuel type was also the key determinant of child CO, with some effect of child position during cooking. The improved stoves in this community have been effective in reducing indoor air pollution and child exposure, although both measures were still high by international standards. Large donor-funded stove programmes need to aim for wider acceptance and uptake by the local families. Better stove maintenance is also required.     

Outdoor air pollution, family and neighborhood environment, and asthma in LA FANS children

We examined associations between outdoor air pollution and childhood asthma, using measures of SES, neighborhood quality, and social support from the Los Angeles Family and Neighborhood Survey (LA FANS). We linked residential census tracts for 3114 children to government air monitoring stations and estimated average pollutant concentrations for the year before interview. CO and NO(2) levels increased and O(3) levels decreased as neighborhood quality decreased, yet correlations were low. Pollutant levels were not correlated with neighborhood support. Even after adjustment for social environment characteristics, LA FANS children living in high O(3), PM(10), and CO areas appeared to have worse asthma morbidity.     

Home indoor pollutant exposures among inner-city children with and without asthma

BACKGROUND: Evidence for environmental causes of asthma is limited, especially among African Americans. To look for systematic differences in early life domestic exposures between inner-city preschool children with and without asthma, we performed a study of home indoor air pollutants and allergens. METHODS: Children 2-6 years of age were enrolled in a cohort study in East Baltimore, Maryland. From the child's bedroom, air was monitored for 3 days for particulate matter 0.05]. Settled dust allergen levels (cat, dust mite, cockroach, dog, and mouse) were also similar in bedrooms of asthmatic and control children. CONCLUSIONS: Exposures to common home indoor pollutants and allergens are similar for inner-city preschool children with and without asthma. Although these exposures may exacerbate existing asthma, this study does not support a causative role of these factors for risk of developing childhood asthma.     

Indoor exposures to air pollutants and allergens in the homes of asthmatic children in inner-city Baltimore

This paper presents indoor air pollutant concentrations and allergen levels collected from the homes of 100 Baltimore city asthmatic children participating in an asthma intervention trial. Particulate matter (PM), NO2, and O3 samples were collected over 72 h in the child's sleeping room. Time-resolved PM was also assessed using a portable direct-reading nephelometer. Dust allergen samples were collected from the child's bedroom, the family room, and the kitchen. The mean PM10 concentration, 56.5+/-40.7 microg/m3, is 25% higher than the PM2.5 concentration (N=90), 45.1+/-37.5 microg/m3. PM concentrations measured using a nephelometer are consistent and highly correlated with gravimetric estimates. Smoking households' average PM2.5 and PM10 concentrations are 33-54 microg/m3 greater than those of nonsmoking houses, with each cigarette smoked adding 1.0 microm/m3 to indoor PM2.5 and PM10 concentrations. Large percentages of NO2 and O3 samples, 25% and 75%, respectively, were below the limit of detection. The mean NO2 indoor concentration is 31.6+/-40.2 ppb, while the mean indoor O3 concentration in the ozone season was 3.3+/-7.7 ppb. The levels of allergens are similar to those found in other inner cities. Results presented in this paper indicate that asthmatic children in Baltimore are exposed to elevated allergens and indoor air pollutants. Understanding this combined insult may help to explain the differential asthma burden between inner-city and non-inner-city children.     

Epidemiological studies of air pollution and health effects in areas near roadways with heavy traffic in Tokyo]

Recent concern regarding health effects of air pollution in Japan has concentrated mainly on traffic-induced air pollution and its health effects in large cities. In Japan, where many people in large cities have been living near major roadways, the increase of automobile exhaust due to heavy traffic congestion will predictably cause a greater impact on people living near major roadways. We surveyed the characterization of residential suspended particulate matter (SPM) and nitrogen dioxide (NO2) concentrations along the major roadways in Tokyo, along with a health survey on the respiratory conditions of residents living in the same area, to examine the relationships between indoor pollutant levels, prevalence of respiratory symptoms and distance from roadways. The environmental monitoring was conducted in five phases. Using a newly developed SPM sampler and NO2 filter badge, continuous 4 day (96 hours) measurements were conducted in two hundred residential homes for four weeks. NO2 was measured in the living room, kitchen and outside of each home, while SPM was monitored in the living room. Health information was collected in October 1987 using ATS-DLD self-administered questionnaires. Of the 1,093 homes investigated, responses from 805 homes were received. The following results were obtained. SPM and NO2 concentrations showed large variations. Indoor pollution levels mostly depended on indoor sources, i.e. cigarette smoking and unventilated space heaters, and the effects of those indoor sources were influenced by the building structure with respect to air tightness. An association between increase in pollutant levels and the distance from the roadway was observed. However its effect is small compared to indoor source effects. The prevalence rate of respiratory symptoms was higher in those areas nearest roadways with heavy traffic both in children and adults. These results suggest the presence of a relationship between automobile exhaust and health effects.     

北京市2个大型综合商业场所空气质量污染水平

目的使用室内空气质量自动监测系统对大型综合商业场所室内空气污染物进行连续监测,了解空气质量现况,并分析不同功能区域间空气质量的差异,探讨主要影响因素。方法 2012年12月—2013年2月利用自动监测设备对北京市2个大型综合商业场所的卖场区、餐饮区和影院区进行空气质量的连续监测,监测时间覆盖整个营业期,监测指标为PM10、甲醛、CO和CO2,并对监测结果汇总分析。结果在商业场所内共设置7个监测点,采集有效数据583组。综合商业场所空气中PM10、甲醛、CO和CO2污染水平分别为（100.7±92.4）μg/m3、（0.07±0.032）mg/m3、（3.283±1.358）mg/m3和（0.067±0.006）%,商业场所各区域间（卖场区、餐饮区、影院区）PM10污染水平差异无统计学意义（F=1.023,P=0.36）,而甲醛、CO和CO2的污染水平比较,差异有统计学意义（F值分别为4.787、323.825和92.375,均P〈0.05）。结论商业场所营业期间整体空气质量良好,不同功能区域间空气质量的问题和差异与室内人员活动、通风换气、气流组织及室外大气影响有关。     

Respiratory health and indoor air pollution at high elevation

In this research, the authors sought to provide experimental data on indoor air quality, and the resulting respiratory impact, for a high-elevation (4550 m), rural community in Ladakh, India. This community is of interest because the primarily nomadic residents burn biomass inside the home for heating and cooking. The concentrations of particulate matter (PM), endotoxin, and carbon monoxide were determined for 6 homes. Lung function data and induced sputum samples were collected for 9 female test-home subjects. In addition, lung function data were collected for 84 additional Ladakhi highlanders at this location. Sputum from 3 visiting scientists (sojourners) was collected and analyzed as well. The average PM concentration ranged from 2 mg/m3 to 7 mg/m3, with 85% of the sampled PM sized as respirable. The average endotoxin concentration ranged from 2.4 ng/m3 to 19 ng/m3, and average carbon monoxide levels ranged from 50 ppm to 120 ppm. Lung function values for the highlander population and the test-home subjects were equal to or greater than predicted, despite the highlanders' significant exposure to indoor pollutants. An induced sputum analysis revealed a significantly greater total inflammatory cell count (M +/- SD, 10(5) cell/mg) in the Ladakhi natives than in the sojourners (107.5 +/- 75.2 vs 7.1 +/- 8.1, p < .01). Although the high levels of indoor pollutants did not correlate with significant decrements in lung function, the induced sputum analysis revealed marked airway inflammation dominated by macrophages and neutrophils. It appears that augmented lung mechanics of this high-altitude population are adaptive to reduce the work of breathing; thus, decrements in lung function go undetected because the true predicted values are greater than expected.     

Common household activities are associated with elevated particulate matter concentrations in bedrooms of inner-city Baltimore pre-school children

Asthma disproportionately affects inner-city, minority children in the U.S. Outdoor pollutant concentrations, including particulate matter (PM), are higher in inner-cities and contribute to childhood asthma morbidity. Although children spend the majority of time indoors, indoor PM exposures have been less extensively characterized. There is a public health imperative to characterize indoor sources of PM within this vulnerable population to enable effective intervention strategies. In the present study, we sought to identify determinants of indoor PM in homes of Baltimore inner-city pre-school children. Children ages 2-6 (n=300) who were predominantly African-American (90%) and from lower socioeconomic backgrounds were enrolled. Integrated PM(2.5) and PM(10) air sampling was conducted over a 3-day period in the children's bedrooms and at a central monitoring site while caregivers completed daily activity diaries. Homes of pre-school children in inner-city Baltimore had indoor PM concentrations that were twice as high as simultaneous outdoor concentrations. The mean indoor PM(2.5) and PM(10) concentrations were 39.5+/-34.5 and 56.2+/-44.8 microg/m(3), compared to the simultaneously measured ambient PM(2.5) and PM(10) (15.6+/-6.9 and 21.8+/-9.53 microg/m(3), respectively). Common modifiable household activities, especially smoking and sweeping, contributed significantly to higher indoor PM, as did ambient PM concentrations. Open windows were associated with significantly lower indoor PM. Further investigation of the health effects of indoor PM exposure is warranted, as are studies to evaluate the efficacy of PM reduction strategies on asthma health of inner-city children.