Modeling the resiliency of energy-efficient retrofits in low-income multifamily housing.

Residential energy efficiency and ventilation retrofits (eg, building weatherization, local exhaust ventilation, HVAC filtration) can influence indoor air quality (IAQ) and occupant health, but these measures' impact varies by occupant activity. In this study, we used the multizone airflow and IAQ analysis program CONTAM to simulate the impacts of energy retrofits on indoor concentrations of PM2.5 and NO2 in a low-income multifamily housing complex in Boston, Massachusetts (USA). We evaluated the differential impact of residential activities, such as low- and high-emission cooking, cigarette smoking, and window opening, on IAQ across two seasons. We found that a comprehensive package of energy and ventilation retrofits was resilient to a range of occupant activities, while less holistic approaches without ventilation improvements led to increases in indoor PM2.5 or NO2 for some populations. In general, homes with simulated concentration increases included those with heavy cooking and no local exhaust ventilation, and smoking homes without HVAC filtration. Our analytical framework can be used to identify energy-efficient home interventions with indoor retrofit resiliency (ie, those that provide IAQ benefits regardless of occupant activity), as well as less resilient retrofits that can be coupled with behavioral interventions (eg, smoking cessation) to provide cost-effective, widespread benefits.

Simulating indoor concentrations of NO(2) and PM(2.5) in multifamily housing for use in health-based intervention modeling.

UNLABELLED: Residents of low-income multifamily housing can have elevated exposures to multiple environmental pollutants known to influence asthma. Simulation models can characterize the health implications of changing indoor concentrations, but quantifying the influence of interventions on concentrations is challenging given complex airflow and source characteristics. In this study, we simulated concentrations in a prototype multifamily building using CONTAM, a multizone airflow and contaminant transport program. Contaminants modeled included PM(2.5) and NO(2) , and parameters included stove use, presence and operability of exhaust fans, smoking, unit level, and building leakiness. We developed regression models to explain variability in CONTAM outputs for individual sources, in a manner that could be utilized in simulation modeling of health outcomes. To evaluate our models, we generated a database of 1000 simulated households with characteristics consistent with Boston public housing developments and residents and compared the predicted levels of NO(2) and PM(2.5) and their correlates with the literature. Our analyses demonstrated that CONTAM outputs could be readily explained by available parameters (R(2) between 0.89 and 0.98 across models), but that one-compartment box models would mischaracterize concentrations and source contributions. Our study quantifies the key drivers for indoor concentrations in multifamily housing and helps to identify opportunities for interventions. PRACTICAL IMPLICATIONS: Many low-income urban asthmatics live in multifamily housing that may be amenable to ventilation-related interventions such as weatherization or air sealing, wall and ceiling hole repairs, and exhaust fan installation or repair, but such interventions must be designed carefully given their cost and their offsetting effects on energy savings as well as indoor and outdoor pollutants. We developed models to take into account the complex behavior of airflow patterns in multifamily buildings, which can be used to identify and evaluate environmental and non-environmental interventions targeting indoor air pollutants which can trigger asthma exacerbations.

Sociodemographic and geographic variability in smoking in the U.S.: a multilevel analysis of the 2006-2007 Current Population Survey, Tobacco Use Supplement.

Because smoking is a pervasive risk factor for numerous health outcomes, it is essential to understand smoking patterns in different populations and places. Previous studies have described sociodemographic and geographic variation in smoking across the U.S., providing insight to public health scientists aiming to identify high-risk populations and places in the absence of local data. This study extends previous research by considering the influence of a combination of covariates at the U.S. state, core-based statistical area (CBSA), and individual levels, focusing on a time period when smoking prevalence has decreased significantly but disparities remain. We applied multilevel regression to the 2006-2007 Current Population Survey-Tobacco Use Supplement. We conducted a four-level logistic regression model and evaluated fixed and random effects to quantify the contribution of sociodemographic characteristics at the individual level, area poverty at the CBSA level, and indoor smoking legislation and cigarette taxes at the state level, to the probability of smoking at the individual level and the variance in smoking at the state and CBSA levels. Sociodemographic covariates were significant predictors of smoking and explained 67% of variance at the CBSA level alone but only 41% at the state level. Contextual covariates alone, such as indoor smoking legislation and cigarette taxes at the state level and area poverty at the CBSA level, explained a larger proportion of state variance (82%) but individually had modest statistical significance. Our findings emphasize the continued disparities in smoking patterns in the U.S. despite the decrease of smoking prevalence in the past decade; as well as the ongoing necessity to consider associations with both compositional and contextual factors. Patterns of residual variance emphasize the continued need to identify and evaluate appropriate contextual covariates, with more refined geographic resolution than that available from national surveys at present.

Source apportionment of indoor residential fine particulate matter using land use regression and constrained factor analysis.

UNLABELLED: Source contributions to urban fine particulate matter (PM(2.5) ) have been modelled using land use regression (LUR) and factor analysis (FA). However, people spend more time indoors, where these methods are less explored. We collected 3-4- day samples of nitrogen dioxide and PM(2.5) inside and outside of 43 homes in summer and winter, 2003-2005, in and around Boston, Massachusetts. Particle filters were analysed for black carbon and trace element concentrations using reflectometry, X-ray fluorescence (XRF), and high-resolution inductively coupled mass spectrometry (ICP-MS). We regressed indoor against outdoor concentrations modified by ventilation, isolating the indoor-attributable fraction, and then applied constrained FA to identify source factors in indoor concentrations and residuals. Finally, we developed LUR predictive models using GIS-based outdoor source indicators and questionnaire data on indoor sources. FA using concentrations and residuals reasonably separated outdoor (long-range transport/meteorology, fuel oil/diesel, road dust) from indoor sources (combustion, smoking, cleaning). Multivariate LUR regression models for factors from concentrations and indoor residuals showed limited predictive power, but corroborated some indoor and outdoor factor interpretations. Our approach to validating source interpretations using LUR methods provides direction for studies characterizing indoor and outdoor source contributions to indoor cocentrations. PRACTICAL IMPLICATIONS: By merging indoor-outdoor modeling, factor analysis, and LUR-style predictive regression modeling, we have added to previous source apportionment studies by attempting to corroborate factor interpretations. Our methods and results support the possibility that indoor exposures may be modeled for epidemiologic studies, provided adequate sample size and variability to identify indoor and outdoor source contributions. Using these techniques, epidemiologic studies can more clearly examine exposures to indoor sources and indoor penetration of source-specific components, reduce exposure misclassification, and improve the characterization of the relationship between particle constituents and health effects.

A longitudinal analysis of the efficacy of environmental interventions on asthma-related quality of life and symptoms among children in urban public housing.

In an environmental intervention study in public housing, we examined monthly Juniper Paediatric Asthma Quality of Life (QOL) Questionnaires for 51 children. Longitudinal analysis and spline models were used to identify time periods with significant improvements in QOL to inform judgments about causality. We found significant improvements in QOL, with moderate improvements before environmental interventions, increased rates of improvement immediately after, and reduced rates more than 5 months post-intervention. Effect modification analyses identified high-risk subpopulations and emphasized the importance of environmental, social, and economic conditions. Our results demonstrate the value of longitudinal techniques in evaluating the benefits of environmental interventions for asthma.

Ventilation in public housing: implications for indoor nitrogen dioxide concentrations.

UNLABELLED: Although elevated nitrogen dioxide (NO2) exposures may exacerbate asthma, few studies have examined indoor NO2 levels in low-income, urban neighborhoods, where asthma prevalence is high. As part of the Healthy Public Housing Initiative, NO2 was measured in 77 homes within three Boston public housing developments, using Palmes tubes placed in the kitchen, living room, and outdoors. Air exchange rates (AERs) were assessed using a perfluorocarbon tracer technique. Overall NO2 levels were [mean (ppb)+/-s.d.]: kitchen (43+/-20, n=100), living room (36+/-17, n=102), outdoor (19+/-6, n=91). Indoor NO2 levels were significantly higher in the heating season (living room: 43 ppb vs. 26 ppb, kitchen: 50 ppb vs. 33 ppb), while AERs were significantly lower in the heating season (medians 0.49/h vs. 0.85/h). Significant univariate predictors of indoor concentrations include: outdoor NO2 levels, AERs, and occupancy. AERs and outdoor NO2 remained significant in multivariate models (P<0.05). A dummy variable for supplemental heating with gas stove was not significant (P=0.14), but had a large, positive coefficient. Indoor NO2 levels in this cohort are higher than those generally reported in residential US settings, associated in part with increased gas stove usage and decreased AERs during the heating season. PRACTICAL IMPLICATIONS: Indoor air quality is mainly a function of outdoor concentrations, indoor sources, ventilation, and residential behavior. Indoor exposures to nitrogen dioxide and other combustion pollutants may be elevated within low-income housing developments due to the presence of multiple sources, poor ventilation, small apartment size, and behavioral responses to apartment conditions (e.g. supplemental heating with gas stove). This information may be used by housing authorities and other landlords to decrease potential environmental stressors, through interventions such as source substitution and improved ventilation, particularly for sensitive sub-populations such as asthmatics.

Assessing the public health benefits of reduced ozone concentrations.

In this paper we examine scientific evidence and related uncertainties in two steps of benefit-cost analyses of ozone reduction: estimating the health improvements attributable to reductions in ozone and determining the appropriate monetary values of these improvements. Although substantial evidence exists on molecular and physiologic impacts, the evidence needed to establish concentration-response functions is somewhat limited. Furthermore, because exposure to ozone depends on factors such as air conditioning use, past epidemiologic studies may not be directly applicable in unstudied settings. To evaluate the evidence likely to contribute significantly to benefits, we focus on four health outcomes: premature mortality, chronic asthma, respiratory hospital admissions, and minor restricted activity days. We determine concentration-response functions for these health outcomes for a hypothetical case study in Houston, Texas, using probabilistic weighting reflecting our judgment of the strength of the evidence and the possibility of confounding. We make a similar presentation for valuation, where uncertainty is due primarily to the lack of willingness-to-pay data for the population affected by ozone. We estimate that the annual monetary value of health benefits from reducing ozone concentrations in Houston is approximately $10 per person per microgram per cubic meter (24-hr average) reduced (95% confidence interval, $0.70-$40). The central estimate exceeds past estimates by approximately a factor of five, driven by the inclusion of mortality. We discuss the implications of our findings for future analyses and determine areas of research that might help reduce the uncertainties in benefit estimation.

Fine particulate matter and polycyclic aromatic hydrocarbon concentration patterns in Roxbury, Massachusetts: a community-based GIS analysis.

Given an elevated prevalence of respiratory disease and density of pollution sources, residents of Roxbury, Massachusetts, have been interested in better understanding their exposures to air pollution. To determine whether local transportation sources contribute significantly to exposures, we conducted a community-based pilot investigation to measure concentrations of fine particulate matter (particulate matter < 2.5 microm; PM(2.5)) and particle-bound polycyclic aromatic hydrocarbons (PAHs) in Roxbury in the summer of 1999. Community members carried portable monitors on the streets in a 1-mile radius around a large bus terminal to create a geographic information system (GIS) map of concentrations and gathered data on site characteristics that could predict ambient concentrations. Both PM(2.5) and PAH concentrations were greater during morning rush hours and on weekdays. In linear mixed-effects regressions controlling for temporal autocorrelation, PAH concentrations were significantly higher with closer proximity to the bus terminal (p < 0.05), and both pollutants were elevated, but not statistically significantly so, on bus routes. Regressions on a subset of measurements for which detailed site characteristics were gathered showed higher concentrations of both pollutants on roads reported to have heavy bus traffic. Although a more comprehensive monitoring protocol would be needed to develop robust predictive functions for air pollution, our study demonstrates that pollution patterns in an urban area can be characterized with limited monitoring equipment and that university-community partnerships can yield relevant exposure information.

Particle concentrations in urban microenvironments.

Although ambient particulate matter has been associated with a range of health outcomes, the health risks for individuals depend in part on their daily activities. Information about particle mass concentrations and size distributions in indoor and outdoor microenvironments can help identify high-risk individuals and the significant contributors to personal exposure. To address these issues in an urban setting, we measured particle count concentrations in four size ranges and particulate matter (3/4) 10 microm (PM(10)) concentrations outdoors and in seven indoor microenvironments in Boston, Massachusetts. Particle counts and PM(10) concentrations were continuously measured with two light-scattering devices. Because of the autocorrelation between sequential measurements, we used linear mixed effects models with an AR-1 autoregressive correlation structure to evaluate whether differences between microenvironments were statistically significant. In general, larger particles were elevated in the vicinity of significant human activity, and smaller particles were elevated in the vicinity of combustion sources, with indoor PM(10) concentrations significantly higher than the outdoors on buses and trolleys. Statistical models demonstrated significant variability among some indoor microenvironments, with greater variability for smaller particles. These findings imply that personal exposures can depend on activity patterns and that microenvironmental concentration information can improve the accuracy of personal exposure estimation.

Estimating the mortality impacts of particulate matter: what can be learned from between-study variability?

Epidemiologic studies of the link between particulate matter (PM) concentrations and mortality rates have yielded a range of estimates, leading to disagreement about the magnitude of the relationship and the strength of the causal connection. Previous meta-analyses of this literature have provided pooled effect estimates, but have not addressed between-study variability that may be associated with analytical models, pollution patterns, and exposed populations. To determine whether study-specific factors can explain some of the variability in the time-series studies on mortality from particulate matter [less than/equal to] 10 microm in aerodynamic diameter (PM(10)), we applied an empirical Bayes meta-analysis. We estimate that mortality rates increase on average by 0.7% per 10 microg/m(3) increase in PM(10) concentrations, with greater effects at sites with higher ratios of particulate matter [less than/equal to] 2.5 microm in aerodynamic diameter (PM(2.5))/PM(10). This finding did not change with the inclusion of a number of potential confounders and effect modifiers, although there is some evidence that PM effects are influenced by climate, housing characteristics, demographics, and the presence of sulfur dioxide and ozone. Although further analysis would be needed to determine which factors causally influence the relationship between PM(10) and mortality, these findings can help guide future epidemiologic investigations and policy decisions.

Variabilities in aerosolizing activities and airborne fungal concentrations in a bakery.

Concentrations of airborne culturable fungi were measured in the kitchen of a bakery in Boston, Mass., to evaluate variabilities associated with common worker activities, outdoor aerosol distributions, and season. Activities were categorized as early morning preparation, cornmeal sifting and tossing, flour dumping and mixing, sweeping, and low activity. Sets of measurements were taken over 1 day in spring and 1 day in summer. Fungal concentrations were measured using a one-stage culture plate impactor, and bulk samples were taken from suspected fungal reservoirs within the bakery and subsequently cultured. Compared with the low activity category, elevated levels of total culturable fungi were found during all other activities, with the amount of increase closely related to individual worker activity as well as outdoor concentrations and initial bakery conditions. In the spring, Penicillium was the dominant genus showing activity-related elevations in concentrations, while Cladosporium was the dominant genus during the summer. Clearly, due to variabilities in worker activities and ambient fungal concentrations, a standardized sampling protocol involving a large sample size over multiple days is needed to estimate accurately exposure to either total airborne fungi or specific fungal taxa.

Residential building codes, affordability, and health protection: a risk-tradeoff approach.

Residential building codes intended to promote health and safety may produce unintended countervailing risks by adding to the cost of construction. Higher construction costs increase the price of new homes and may increase health and safety risks through "income" and "stock" effects. The income effect arises because households that purchase a new home have less income remaining for spending on other goods that contribute to health and safety. The stock effect arises because suppression of new-home construction leads to slower replacement of less safe housing units. These countervailing risks are not presently considered in code debates. We demonstrate the feasibility of estimating the approximate magnitude of countervailing risks by combining the income effect with three relatively well understood and significant home-health risks. We estimate that a code change that increases the nationwide cost of constructing and maintaining homes by $150 (0.1% of the average cost to build a single-family home) would induce offsetting risks yielding between 2 and 60 premature fatalities or, including morbidity effects, between 20 and 800 lost quality-adjusted life years (both discounted at 3%) each year the code provision remains in effect. To provide a net health benefit, the code change would need to reduce risk by at least this amount. Future research should refine these estimates, incorporate quantitative uncertainty analysis, and apply a full risk-tradeoff approach to real-world case studies of proposed code changes.

Determinants of nitrogen dioxide concentrations in indoor ice skating rinks.

OBJECTIVES: The combination of poor ventilation and fuel-powered ice resurfacers has resulted in elevated nitrogen dioxide (NO2) concentrations in many indoor ice skating rinks. This study examined the factors influencing concentrations and the effects of various engineering controls in ice rinks with different resurfacer fuels. METHODS: Indoor NO2 concentrations were measured in 19 enclosed ice skating rinks over 3 winters by means of passive samplers, with 1-week average measurements during the first winter pilot study and single-day working-hour measurements in the final 2 winters. Personal exposures to drivers also were assessed during the last winter. RESULTS: Rinks in which propane-fueled resurfacers were used had a daily mean indoor NO2 concentration of 206 ppb, compared with 132 ppb for gasoline-fueled and 37 ppb for electric-powered resurfacers. Engineering controls, such as increased ventilation and resurfacer tuning, reduced NO2 concentrations by 65% on average, but outcomes varied widely, and concentrations increased in subsequent months. CONCLUSIONS: Electric ice resurfacers, increased ventilation, or emission control systems are recommended to protect the health of workers and patrons, with surveillance programs proposed to track implementation and maintain an observer effect.

The Boston residential nitrogen dioxide characterization study: classification and prediction of indoor NO2 exposure.

Many epidemiological studies have used house characteristics associated with indoor sources as simplified proxies for personal nitrogen dioxide (NO2) exposure. Stove type and presence of a pilot light often been used as the two key characteristics, but significant overlaps have remained in the NO2 concentrations in the exposed and unexposed groups. This has contributed to inconsistencies in epidemiological findings, due to potential misclassification of exposure. In this study, other possible proxies were analyzed by cross-table analyses and were investigated in terms of improvements in both classification and predictive power. Adding building type to the above two proxies resulted in 0-5% of households with concentrations overlapping the observed range for the opposing stratum, compared with 22-42% for the two-proxy model. In spite of this performance, the predictive power of regression models for indoor NO2 was not improved by the addition of the third proxy, and the potential sample population was significantly limited. Using these analytical methods to choose descriptive proxies and evaluate the tradeoffs in their implementation can help epidemiological studies improve their designs and therefore optimize the robustness of their conclusions.

Impact of residential nitrogen dioxide exposure on personal exposure: an international study.

Nitrogen dioxide (NO2) concentrations were measured during two-day winter periods in indoor and outdoor environments, and these concentrations were compared with simultaneously measured personal exposures in 18 cities in 15 countries around the world. Information was also gathered on activity patterns and household characteristics in order to determine the influences of these factors on personal exposures. All NO2 measurements were taken using passive filter badges. Personal exposures were found to vary greatly among the array of cities, with mean concentrations ranging between 11.0 ppb and 51.5 ppb. Personal NO2 exposures were more strongly correlated with indoor concentrations (r = 0.75) than with outdoor concentrations (r = 0.57) when all countries were considered simultaneously. Use of a gas stove in the home was the dominant activity influencing NO2 concentrations, with a 67% increase in mean personal NO2 exposure and an increase in indoor-outdoor ratios from 0.7 to 1.2 for participants using gas stoves, although preliminary evidence indicates the importance of combustion space heaters as well. These associations indicate the global nature of the correlation between personal NO2 exposures and indoor NO2 sources such as gas stoves or space heaters, demonstrating that this relationship is not dependent on country-specific parameters.

Unusual skeletal metastases in carcinoma of the cervix.

In a series of 1347 patients with carcinoma of the cervix, 62 or 4.6% had metastatic spread to the bones. Bone metastasis correlated with more advanced disease, occurring in 39.1% of patients with Stage II disease. The role of isotope bone scanning and of the radiographic skeletal survey in the investigation of carcinoma of the cervix is considered. Eight patients having unusual radiographic appearances of skeletal metastases are discussed.

A villous tumour of the duodenum with malignant change in a child: A case report.

A tubulovillous adenoma of the duodenum with a predominant villous pattern in a child aged 11 years underwent malignant change, causing obstructive jaundice, and was diagnosed by percutaneous transhepatic cholangiography. Two of the patient's 9 siblings had previously died of cancer. A review of villous tumours of the duodenum is given.