Biomedical subjects

Brent A Coull

Publications and source records attributed to Brent A Coull.

At least 19 recordsLinked to original sources

PubMed2007

Focused exposures to airborne traffic particles and heart rate variability in the elderly.

BACKGROUND: : Exposure to airborne particles may increase cardiac risk by altering autonomic balance. Because these risks may be particularly great for traffic-related particles, we examined associations between particles and heart rate variability as 44 subjects participated in 4 repeated trips aboard a diesel bus. METHODS: : Twenty-four hour electrocardiograms were correlated with continuous particle concentrations using generalized additive models controlling for subject, weekday, time, apparent temperature, trip type, activity, medications, and autoregressive terms. Associations were assessed for short- and medium-term moving averages of measured concentrations. RESULTS: : Heart rate variability was negatively associated with fine particulate matter. Positive associations were demonstrated with heart rate and the low-to-high frequency power ratio. Associations were strongest with 24-hour mean concentrations, although strong short-term associations also were found during bus periods, independent of daily exposures. Overall, associations were greatest for high-frequency power with the following effects per interquartile change in the 24-hour mean concentrations: -15% (95% confidence interval = -17% to -14%) for PM2.5 (4.6 mug/m); -19% (-21% to -17%) for black carbon (459 ng/m); and -14% (-15% to -12%) for fine particle counts (39 pt/cm). For each interquartile change in the 5-minute PM2.5 concentration (10 mug/m) aboard the bus, an 11% (95% confidence interval = -14% to -8%) decrease in high-frequency power was observed. CONCLUSIONS: : This investigation indicates that fine particles are negatively associated with heart rate variability, with an overall trend towards reduced parasympathetic tone. Although daily associations were evident for all particles, short-term associations were predominantly limited to traffic-related particles.

Age Factors↗

PubMed2006

An informative Bayesian structural equation model to assess source-specific health effects of air pollution.

A primary objective of current air pollution research is the assessment of health effects related to specific sources of air particles or particulate matter (PM). Quantifying source-specific risk is a challenge because most PM health studies do not directly observe the contributions of the pollution sources themselves. Instead, given knowledge of the chemical characteristics of known sources, investigators infer pollution source contributions via a source apportionment or multivariate receptor analysis applied to a large number of observed elemental concentrations. Although source apportionment methods are well established for exposure assessment, little work has been done to evaluate the appropriateness of characterizing unobservable sources thus in health effects analyses. In this article, we propose a structural equation framework to assess source-specific health effects using speciated elemental data. This approach corresponds to fitting a receptor model and the health outcome model jointly, such that inferences on the health effects account for the fact that uncertainty is associated with the source contributions. Since the structural equation model (SEM) typically involves a large number of parameters, for small-sample settings, we propose a fully Bayesian estimation approach that leverages historical exposure data from previous related exposure studies. We compare via simulation the performance of our approach in estimating source-specific health effects to that of 2 existing approaches, a tracer approach and a 2-stage approach. Simulation results suggest that the proposed informative Bayesian SEM is effective in eliminating the bias incurred by the 2 existing approaches, even when the number of exposures is limited. We employ the proposed methods in the analysis of a concentrator study investigating the association between ST-segment, a cardiovascular outcome, and major sources of Boston PM and discuss the implications of our findings with respect to the design of future PM concentrator studies.

Air Pollution↗

PubMed2006

Asymmetry of skeletal effects of Dominant hemimelia.

BACKGROUND: Dominant hemimelia (Dh) is a dominant mutation that arose spontaneously in mice; Dh animals exhibit reduced numbers of lumbar vertebrae and preaxial hindlimb defects. Absence of spleen occurs in both Dh/+ and Dh/Dh animals. This study was undertaken to characterize asymmetry of skeletal defects in the Dh mouse, specifically hindlimb asymmetries in association with axial defects. METHODS: A total of 29 Dh/+ and 100 +/+ fetuses (gestational day [GD] 18) were identified by phenotype and linked DNA and their skeletons were analyzed. RESULTS: The results revealed an asymmetry of hindlimb skeletal defects in Dh/+ animals. In +/+ fetuses, the left and right tibia were symmetrical with 99.0% of the animals possessing 6 lumbar vertebrae. However, Dh/+ fetuses showed asymmetry in length of left and right tibia and a reduction to 5 lumbar vertebrae in 86.2% of animals. There was a range from mild to severe asymmetry as evidenced by direct comparison of the length of the left to the right tibia of each animal. Tibial shortening was greater on the left than the right in 65.5% of Dh/+ fetuses; only 20.7% had symmetrical tibia. Oligodactyly, defined as absence of the first or second toe, was similarly more frequent on the left. CONCLUSIONS: Asymmetry is characteristic of many human limb malformations, although analysis of the molecular basis is difficult. Therefore, Dh/+ mice, which exhibit reduced numbers of lumbar vertebrae, asymmetric hindlimb defects, and complete absence of spleen, provide an important model for studying the relationship between axial patterning and asymmetric skeletal defects.

Animals↗

PubMed2006

Race/ethnicity and changing US socioeconomic gradients in breast cancer incidence: California and Massachusetts, 1978-2002 (United States).

OBJECTIVE: We tested the hypothesis that the US socioeconomic gradient in breast cancer incidence is declining, with the decline most pronounced among racial/ethnic groups with the highest incidence rates. METHODS: We geocoded the invasive incident breast cancer cases for three US population-based cancer registries covering: Los Angeles County, CA (1978-1982, 1988-1992, 1998-2002; n = 68,762 cases), the San Francisco Bay Area, CA (1978-1982, 1988-1992, 1998-2002; n = 37,210 cases) and Massachusetts (1988-1992, 1998-2002; n = 48,111 cases), linked the records to census tract area-based socioeconomic measures, and, for each socioeconomic stratum, computed average annual breast cancer incidence rates for the 5-year period straddling the 1980, 1990, and 2000 census, overall and by race/ethnicity and gender. RESULTS: Our findings indicate that the socioeconomic gradient in breast cancer incidence is: (a) relatively small (at most 1.2) and stable among US white non-Hispanic and black women; (b) sharper and generally increasing among Hispanic and Asian and Pacific Islander American women; and (c) cannot be meaningfully analyzed without considering effect modification by race/ethnicity and immigration. CONCLUSION: Our results indicate that secular changes in US socioeconomic gradients in breast cancer incidence exist and vary by race/ethnicity.

Breast Neoplasms↗

PubMed2006

Mapping and measuring social disparities in premature mortality: the impact of census tract poverty within and across Boston neighborhoods, 1999-2001.

The identification and documentation of health disparities are important functions of public health surveillance. These disparities, typically falling along lines defined by gender, race/ethnicity, and social class, are often made visible in urban settings as geographic disparities in health between neighborhoods. Recognizing that premature mortality is a powerful indicator of disparities in both health status and access to health care that can readily be monitored using routinely available public health surveillance data, we undertook a systematic analysis of spatial variation in premature mortality in Boston (1999-2001) across neighborhoods and sub-neighborhoods in relation to census tract (CT) poverty. Using a multilevel model based framework, we estimated that the incidence of premature mortality was 1.39 times higher (95% credible interval 1.09-1.78) among persons living in the most economically deprived CTs (>/=20% below poverty) compared to those in the least impoverished tracts (<5% below poverty). We present maps of model-based standardized mortality ratios that show substantial within-neighborhood variation in premature mortality and a sizeable decrease in spatial variation after adjustment for CT poverty. Additionally, we present maps of model-based direct standardized rates that can more readily be compared to externally published rates and targets, as well as maps of the population attributable fraction that show that in some of Boston's poorest neighborhoods, the proportion of excess deaths associated with CT poverty reaches 25-30%. We recommend that these methods be incorporated into routine analyses of public health surveillance data to highlight continuing social disparities in premature mortality.

Adolescent↗

PubMed2006

Effects of ambient particles and carbon monoxide on supraventricular arrhythmias in a rat model of myocardial infarction.

The association between short-term increases in particulate air pollution and increased cardiovascular morbidity and mortality is well documented. Recent studies suggest an association between particulate matter with aerodynamic diameter < 2.5 microm (PM2.5) and supraventricular arrhythmias (SVA), but the results have been inconsistent. We evaluated this hypothesis in a rat model of acute myocardial infarction (AMI). Diazepam-sedated Sprague-Dawley rats with AMI were exposed (1 h) to either filtered air (n = 16), concentrated ambient fine particles (CAPS; mean = 645.7 microg/m3; n = 23), carbon monoxide (CO; 35 ppm; n = 19), or CAPs and CO (n = 24). Each exposure was immediately preceded and followed by a 1-h exposure to filtered air (baseline and postexposure periods, respectively). Surface electrocardiograms were recorded and the frequency of supraventricular premature beats was quantified. Among rats in the CAPS group, the probability of observing any SVA decreased from baseline to the exposure and postexposure periods. This pattern was significantly different than that observed for the filtered air group during the exposure period (p = .048) only. In the subset of rats with one or more SVA during the baseline period, the change in SVA rate from baseline to exposure period was significantly lower in the CAPS (p = .04) and CO (p = .007) groups only, as compared to the filtered air group. No significant effects were observed in the group simultaneously exposed to CAPS and CO. Thus, the results of this study do not support the hypothesis that exposure to ambient air pollution increases the risk or frequency of supraventricular arrhythmias.

Air Pollutants↗

PubMed2006

The influences of ambient particle composition and size on particle infiltration in Los Angeles, CA, residences.

Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH4NO3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (FINF), for fine particles (PM2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO3-]) components, and particle sizes ranging between 0.02 and 10 microm. FINF was highest for BC (median = 0.84) and lowest for NO3- (median = 0.18). The low FINF for NO3- was likely because of volatilization of NO3- particles once indoors, in addition to depositional losses upon building entry. The FINF for PM2.5 (median = 0.48) fell between those for BC and NO3-, reflecting the contributions of both particle components to PM25. FINF varied with particle size, air-exchange rate, and outdoor NO3- concentrations. The FINF for particles between 0.7 and 2 microm in size was considerably lower during periods of high as compared with low outdoor NO3- concentrations, suggesting that outdoor NO3- particles were of this size. This study demonstrates that infiltration of PM2.5 varies by particle component and is lowest for volatile species, such as NH4NO3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas with high concentrations of NH4NO3 and other volatile particles.

Air Pollutants↗

PubMed2006

Short-term effects of air pollution on heart rate variability in senior adults in Steubenville, Ohio.

OBJECTIVE: We examined the association between ambient air pollution levels and heart rate variability (HRV) in a panel study of 32 subjects. METHODS: We used linear mixed models to analyze the effects of fine particles (PM2.5), sulfate (SO4), elemental carbon (EC), and gases on log-transformed standard deviation of normal RR intervals (SDNN), mean square of differences between adjacent RR intervals (r-MSSD), and high- and low-frequency power (HF, LF). RESULTS: An interquartile range (IQR) increase of 5.1 mug/m in SO4 on the previous day was associated with a decrease of -3.3% SDNN (95% confidence = -6.0% to -0.5%), -5.6% r-MSSD (-10.7% to -0.2%), and -10.3% HF (-19.5% to -0.1%). Associations with total PM2.5 were similar. HRV was not associated with EC, NO2, SO2, or O3. CONCLUSION: In addition to traffic-related particles, elevated levels of sulfate particles may also adversely affect autonomic function.

Aged↗

PubMed2006

Feature-specific penalized latent class analysis for genomic data.

Genomic data are often characterized by a moderate to large number of categorical variables observed for relatively few subjects. Some of the variables may be missing or noninformative. An example of such data is loss of heterozygosity (LOH), a dichotomous variable, observed on a moderate number of genetic markers. We first consider a latent class model where, conditional on unobserved membership in one of k classes, the variables are independent with probabilities determined by a regression model of low dimension q. Using a family of penalties including the ridge and LASSO, we extend this model to address higher-dimensional problems. Finally, we present an orthogonal map that transforms marker space to a space of "features" for which the constrained model has better predictive power. We demonstrate these methods on LOH data collected at 19 markers from 93 brain tumor patients. For this data set, the existing unpenalized latent class methodology does not produce estimates. Additionally, we show that posterior classes obtained from this method are associated with survival for these patients.

Biometry↗

PubMed2006

Factors affecting the association between ambient concentrations and personal exposures to particles and gases.

Results from air pollution exposure assessment studies suggest that ambient fine particles [particulate matter with aerodynamic diameter<or=2.5 microg (PM2.5)], but not ambient gases, are strong proxies of corresponding personal exposures. For particles, the strength of the personal-ambient association can differ by particle component and level of home ventilation. For gases, however, such as ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), the impact of home ventilation on personal-ambient associations is untested. We measured 24-hr personal exposures and corresponding ambient concentrations to PM2.5, sulfate (SO2-(4)), elemental carbon, O3, NO2, and SO2 for 10 nonsmoking older adults in Steubenville, Ohio. We found strong associations between ambient particle concentrations and corresponding personal exposures. In contrast, although significant, most associations between ambient gases and their corresponding exposures had low slopes and R2 values; the personal-ambient NO2 association in the fall season was moderate. For both particles and gases, personal-ambient associations were highest for individuals spending most of their time in high- compared with low-ventilated environments. Cross-pollutant models indicated that ambient particle concentrations were much better surrogates for exposure to particles than to gases. With the exception of ambient NO2 in the fall, which showed moderate associations with personal exposures, ambient gases were poor proxies for both gas and particle exposures. In combination, our results suggest that a) ventilation may be an important modifier of the magnitude of effect in time-series health studies, and b) results from time-series health studies based on 24-hr ambient concentrations are more readily interpretable for particles than for gases.

Aged↗

PubMed2006

Diabetes, obesity, and hypertension may enhance associations between air pollution and markers of systemic inflammation.

Airborne particulate matter (PM) may lead to increased cardiac risk through an inflammatory pathway. Therefore, we investigated associations between ambient PM and markers of systemic inflammation among repeated measures from 44 senior citizens (>/= 60 years of age) and examined susceptibility by conditions linked to chronic inflammation. Mixed models were used to identify associations between concentrations of fine PM [aerodynamic diameter </= 2.5 microm (PM2.5)] averaged over 1-7 days and measures of C-reactive protein (CRP) , interleukin-6 (IL-6) , and white blood cells (WBCs) . Effect modification was investigated for diabetes, obesity, hypertension, and elevated mean inflammatory markers. We found positive associations between longer moving averages of PM2.5 and WBCs across all participants, with a 5.5% [95% confidence interval (CI) , 0.10 to 11%] increase per interquartile increase (5.4 microg/m3) of PM2.5 averaged over the previous week. PM2.5 and CRP also exhibited positive associations among all individuals for averages longer than 1 day, with the largest associations for persons with diabetes, obesity, and hypertension. For example, an interquartile increase in the 5-day mean PM)2.5 (6.1 microg/m3) was associated with a 14% increase in CRP (95% CI, -5.4 to 37%) for all individuals and an 81% (95% CI, 21 to 172%) increase for persons with diabetes, obesity, and hypertension. Persons with diabetes, obesity, and hypertension also exhibited positive associations between PM2.5 and IL-6. Individuals with elevated mean inflammatory markers exhibited enhanced associations with CRP, IL-6, and WBCs. We found modest positive associations between PM2.5 and indicators of systemic inflammation, with larger associations suggested for individuals with diabetes, obesity, hypertension, and elevated mean inflammatory markers.

Aged↗

PubMed2005

Lifetime socioeconomic position and twins' health: an analysis of 308 pairs of United States women twins.

BACKGROUND: Important controversies exist about the extent to which people's health status as adults is shaped by their living conditions in early life compared to adulthood. These debates have important policy implications, and one obstacle to resolving them is the relative lack of sufficient high-quality data on childhood and adult socioeconomic position and adult health status. We accordingly compared the health status among monozygotic and dizygotic women twin pairs who lived together through childhood (until at least age 14) and subsequently were discordant or concordant on adult socioeconomic position. This comparison permitted us to ascertain the additional impact of adult experiences on adult health in a population matched on early life experiences. METHODS AND FINDINGS: Our study employed data from a cross-sectional survey and physical examinations of twins in a population-based twin registry, the Kaiser Permanente Women Twins Study Examination II, conducted in 1989 to 1990 in Oakland, California, United States. The study population was composed of 308 women twin pairs (58% monozygotic, 42% dizygotic); data were obtained on childhood and adult socioeconomic position and on blood pressure, cholesterol, post-load glucose, body mass index, waist-to-hip ratio, physical activity, and self-rated health. Health outcomes among adult women twin pairs who lived together through childhood varied by their subsequent adult occupational class. Cardiovascular factors overall differed more among monozygotic twin pairs that were discordant compared to concordant on occupational class. Moreover, among the monozygotic twins discordant on adult occupational class, the working class twin fared worse and, compared to her professional twin, on average had significantly higher systolic blood pressure (mean matched difference = 4.54 mm Hg; 95% confidence interval [CI], 0.10-8.97), diastolic blood pressure (mean matched difference = 3.80 mm Hg; 95% CI, 0.44-7.17), and low-density lipoprotein cholesterol (mean matched difference = 7.82 mg/dl; 95% CI, 1.07-14.57). By contrast, no such differences were evident for analyses based on educational attainment, which does not capture post-education socioeconomic position. CONCLUSION: These results provide novel evidence that lifetime socioeconomic position influences adult health and highlight the utility of studying social plus biological aspects of twinship.

Adolescent↗

PubMed2005

The correlation of deficits in IQ with midface and digit hypoplasia in children exposed in utero to anticonvulsant drugs.

OBJECTIVE: Children exposed during pregnancy to the anticonvulsant drugs phenytoin, phenobarbital, and carbamazepine as monotherapy and polytherapy have an increased frequency of midface and digit hypoplasia. Some children also have cognitive dysfunction. The hypothesis tested is that the anticonvulsant drug-exposed child with midface and digit hypoplasia is more likely to have cognitive dysfunction. METHODS: Children exposed to anticonvulsant drugs (n = 80) were recruited for a follow-up evaluation, which included testing cognitive function and a physical examination for head size, height, and the presence of midface and digit hypoplasia. Microcephaly, midface and digit hypoplasia, and major malformations were correlated with full scale (FSI), performance (PIQ) and verbal (VIQ) intelligence. RESULTS: The presence of the 3 anticonvulsant-exposed children with microcephaly had a deficit of 23.7 IQ points in FSI in comparison with the other children with a normal head size. Either midface or digit hypoplasia, after excluding the persons with microcephaly and with the Bonferroni correction, correlated significantly with deficits in VIQ (-12.7), PIQ (-10) and FSI (-12.8) IQ points ( P = .0061). There was no decrease in IQ in association with major malformations. CONCLUSION: The presence of midface and digit hypoplasia in a child exposed to anticonvulsant drugs in pregnancy is an indication for a systematic developmental evaluation.

Abnormalities, Drug-Induced↗

PubMed2005

Ambient gas concentrations and personal particulate matter exposures: implications for studying the health effects of particles.

BACKGROUND: Data from a previous study conducted in Baltimore, MD, showed that ambient fine particulate matter less than 2.5 mum in diameter (PM2.5) concentrations were strongly correlated with corresponding personal PM2.5 exposures, whereas ambient O3, NO2, and SO2 concentrations were weakly correlated with their personal exposures to these gases. In contrast, many of the ambient gas concentrations were reasonable surrogates of personal PM2.5 exposures. METHODS: Personal multipollutant exposures and corresponding ambient air pollution concentrations were measured for 43 subjects living in Boston, MA. The cohort consisted of 20 healthy senior citizens and 23 schoolchildren. Simultaneous 24-hour integrated PM2.5, O3, NO2, and SO2 personal exposures and ambient concentrations were measured. All PM2.5 samples were also analyzed for SO4 (sulfate). We analyzed personal exposure and ambient concentration data using correlation and mixed model regression analyses to examine relationships among (1) ambient PM2.5 concentrations and corresponding ambient gas concentrations; (2) ambient PM2.5 and gas concentrations and their respective personal exposures; (3) ambient gas concentrations and corresponding personal PM2.5 exposures; and (4) personal PM2.5 exposures and corresponding personal gas exposures. RESULTS: We found substantial correlations between ambient PM2.5 concentrations and corresponding personal exposures over the course of time. Additionally, our results support the earlier finding that summertime gaseous pollutant concentrations may be better surrogates of personal PM2.5 exposures (especially personal exposures to PM2.5 of ambient origin) than they are surrogates of personal exposures to the gases themselves. CONCLUSIONS: Particle health effects studies that include both ambient PM2.5 and gaseous concentrations as independent variables must be analyzed carefully and interpreted cautiously, since both parameters may be serving as surrogates for PM2.5 exposures.

Aged↗

PubMed2005

Air pollution and ST-segment depression in elderly subjects.

Increased levels of daily ambient particle pollution have been associated with increased risk of cardiovascular morbidity. Black carbon (BC) is a measure of the traffic-related component of particles. We investigated associations between ambient pollution and ST-segment levels in a repeated-measures study including 269 observations on 24 active Boston residents 61-88 years of age, each observed up to 12 times from June through September 1999. The protocol involved continuous Holter electrocardiogram monitoring including 5 min of rest, 5 min of standing, 5 min of exercise outdoors, 5 min of recovery, and 20 cycles of paced breathing. Pollution-associated ST-depression was estimated for a 10th- to 90th-percentile change in BC. We calculated the average ST-segment level, referenced to the P-R isoelectric values, for each portion of the protocol. The mean BC level in the previous 12 hr, and the BC level 5 hr before testing, predicted ST-segment depression in most portions of the protocol, but the effect was strongest in the postexercise periods. During postexercise rest, an elevated BC level was associated with -0.1 mm ST-segment depression (p = 0.02 for 12-hr mean BC; p = 0.001 for 5-hr BC) in continuous models. Elevated BC also predicted increased risk of ST-segment depression > or = 0.5 mm among those with at least one episode of that level of ST-segment depression. Carbon monoxide was not a confounder of this association. ST-segment depression, possibly representing myocardial ischemia or inflammation, is associated with increased exposure to particles whose predominant source is traffic.

Aged↗

PubMed2005

Characterization of particulate and gas exposures of sensitive subpopulations living in Baltimore and Boston.

Personal exposures to particulate and gaseous pollutants and corresponding ambient concentrations were measured for 56 subjects living in Baltimore, Maryland, and 43 subjects living in Boston, Massachusetts. The 3 Baltimore cohorts consisted of 20 healthy older adults (seniors), 21 children, and 15 individuals with physician-diagnosed chronic obstructive pulmonary disease (COPD*). The 2 Boston cohorts were 20 healthy seniors and 23 children. All children were 9 to 13 years of age; seniors were 65 years of age or older; and the COPD participants had moderate to severe physician-diagnosed COPD. Personal exposures to particulate matter with aerodynamic diameters less than 2.5 microm (PM2.5), sulfate (SO(4)2-), elemental carbon (EC), ozone (03), nitrogen dioxide (NO2), and sulfur dioxide (SO2) were measured simultaneously for 24 hours/day. All subjects were monitored for 8 to 12 consecutive days. The primary objectives of this study were (1) to characterize the personal particulate and gaseous exposures for individuals sensitive to PM health effects and (2) to assess the appropriateness of exposure assessment strategies for use in PM epidemiologic studies. Personal exposures to multiple pollutants and ambient concentrations were measured for subjects from each cohort from each location. Pollutant data were analyzed using correlation and mixed-model regression analyses. In Baltimore, personal PM2.5 exposures tended to be comparable to (and frequently lower than) corresponding ambient concentrations; in Boston, the personal exposures were frequently higher. Overall, personal exposures to the gaseous pollutants, especially O3 and SO2, were considerably lower than corresponding ambient concentrations because of the lack of indoor sources for these gases and their high removal rate on indoor surfaces. Further, the impact of ambient particles on personal exposure (the infiltration factor) and differences in infiltration factor by city, season, and cohort were investigated. No difference in infiltration factor was found among the cohorts, which suggests that all subjects were exposed to the same fraction of ambient PM2.5 for a given ambient concentration. In addition, the results show significant correlations between ambient PM2.5 concentrations and corresponding personal exposures over time and provide further indication that ambient gaseous pollutant concentrations may be better surrogates for personal PM2.5 exposures, especially personal exposures to PM2.5 of ambient origin, than their respective personal exposures. These results have important implications for PM health effects studies that use regression models including both ambient PM2.5 and gaseous pollutant concentrations as independent variables, because both parameters may be serving as surrogates for PM2.5 exposures.

Adolescent↗

PubMed2004

Ambient air pollution and oxygen saturation.

We investigated the association between fine particulate air pollution and oxygen saturation as measured with a peripheral oxygen saturation monitor during a 12-week repeated-measures study of 28 older Boston residents. Oxygen saturation and air pollution particulates with a mean diameter less than or equal to 2.5 microm were measured continuously during a protocol of rest, standing, exercise, postexercise rest, and 20 cycles of slow, paced breathing. In fixed-effect models, mean pollution concentration was associated with reduced oxygen saturation during the baseline rest period (6 hours: mean, -0.173%; 95% confidence interval [CI], -0.345 to -0.001), postexercise (6 hours: mean, -0.173%; 95% CI, -0.332 to -0.014), with a trend toward decrease during postexercise paced breathing (6 hours: mean, -0.142%; 95% CI, -0.292 to 0.007) but not during exercise. Participants taking beta-blockers had a greater pollution-related decrease in oxygen saturation at rest (6 hours: mean, -0.769%; 95% CI, -1.210 to -0.327) (interaction for particulates with a mean diameter less than or equal to 2.5 microm by beta-blocker, p < 0.0005) than did those not taking beta-blockers (p > 0.25). The reduction in oxygen saturation associated with air pollution may result from subtle particulate-related pulmonary vascular and/or inflammatory changes. Further investigation may contribute to our understanding of the mechanisms through which particulates may increase respiratory and cardiac morbidity among vulnerable populations.

Adrenergic beta-Antagonists↗

PubMed2004

Cardiac effects of carbon monoxide and ambient particles in a rat model of myocardial infarction.

Ambient air pollution is a complex mixture of particulate matter (PM) and gaseous pollutants such as carbon monoxide (CO). The effect of exposure to CO, alone or in combination with ambient PM, on arrhythmia incidence is unclear. To evaluate these effects, left-ventricular myocardial infarction was induced in Sprague-Dawley rats by thermocoagulation. Diazepam-sedated rats were exposed (1 h) to either filtered air (n = 40), CO (35 ppm, n = 19), concentrated air particles (CAPs, median concentration = 350.5 microg/m(3), n = 53), or CAPs and CO (CAPs median concentration = 318.2 microg/m(3), n = 23), 12-18 h after surgery. Each exposure was immediately preceded and followed by a 1 h exposure to filtered air (pre-exposure and post-exposure periods, respectively). The CO target dose of 35 ppm is related to the 1 h U.S. National Ambient Air Quality Standard. Surface electrocardiograms were recorded and heart rate and arrhythmia incidence were quantified. CO exposure reduced ventricular premature beat (VPB) frequency by 60.4% (p = 0.012) during the exposure period compared to controls. This effect was modified by both infarct type and the number of pre-exposure VPBs, and was not mediated through changes in heart rate. Overall, CAPs exposure increased VPB frequency during the exposure period, but this effect did not reach statistical significance. This effect was modified by the number of pre-exposure VPBs. Overall, neither CAPs nor CO had any effect on heart rate, but CAPs increased heart rate in specific subgroups. No significant interactions were observed between the effects of CO and CAPs. In this animal model, the responses to CO and CAPs are distinctly different.

Air Pollutants↗