Short-term effects of particulate air pollution on cardiovascular diseases in eight European cities

Effects of bushfire smoke on daily mortality and hospital admissions in Sydney, Australia

BACKGROUND

Little research has investigated the health effects of particulate exposure from bushfires (also called wildfires, biomass fires, or vegetation fires), and these exposures are likely to increase, for several reasons. We investigated associations of daily mortality and hospital admissions with bushfire-derived particulates, compared with particulates from urban sources in Sydney, Australia from 1994 through 2002.

METHODS

On days with the highest particulate matter (PM)10 concentrations, we assumed PM10 was due primarily to bushfires. We calculated the contribution of bushfire PM10 on these days by subtracting the background PM10 concentration estimated from surrounding days. We assumed PM10 on the remaining days was from usual urban sources. We implemented a Poisson model, with a bootstrap-based methodology, to select optimum smoothed covariate functions, and we estimated the effects of bushfire PM10 and urban PM10, lagged up to 3 days.

RESULTS

We identified 32 days with extreme PM10 concentrations due to bushfires or vegetation-reduction burns. Although bushfire PM10 was consistently associated with respiratory hospital admissions, we found no consistent associations with cardiovascular admissions or with mortality. A 10 microg/m increase in bushfire PM10 was associated with a 1.24% (95% confidence interval = 0.22% to 2.27%) increase in all respiratory disease admissions (at lag 0), a 3.80% (1.40% to 6.26%) increase in chronic obstructive pulmonary disease admissions (at lag 2), and a 5.02% (1.77% to 8.37%) increase in adult asthma admissions (at lag 0). Urban PM10 was associated with all-cause and cardiovascular mortality, as well as with cardiovascular and respiratory hospital admission, and these associations were not influenced by days with extreme PM10 concentrations.

CONCLUSIONS

PM10 from bushfires is associated primarily with respiratory morbidity, while PM10 from urban sources is associated with cardiorespiratory mortality and morbidity.

Air pollution positively correlates with daily stroke admission and in hospital mortality: a study in the urban area of Como, Italy

Some current evidences suggest that stroke incidence and mortality may be higher in elevated air pollution areas. Our study examined the hypothesis of a correlation between air pollution level and ischemic stroke admission and in Hospital mortality in an urban population. Data on a total of 759 stroke admissions and 180 deaths have been obtained over a 4-year period (2000-2003). Five air ambient particles have been studied. A general additive model estimating Poisson distribution has been used, adding meteorological variables as covariates. NO(2) and PM(10) were significantly associated with admission and mortality (P value < 0.05) and with estimated RR of 1.039 (95% CI 1.066-1.013) and 1.078 (95% CI 1.104-1.052) for hospital admission at 2- and 4-day lags, respectively. In conclusion, this study suggests an association between short-term outdoor air pollution exposure and ischemic stroke admission and mortality.

Fine particulate air pollution and its components in association with cause-specific emergency admissions

BACKGROUND

Although the association between exposure to particulate matter and health is well established, there remains uncertainty as to whether certain chemical components are more harmful than others. We explored whether the association between cause-specific hospital admissions and PM(2.5) was modified by PM(2.5) chemical composition.

METHODS

We estimated the association between daily PM(2.5) and emergency hospital admissions for cardiac causes (CVD), myocardial infarction (MI), congestive heart failure (CHF), respiratory disease, and diabetes in 26 US communities, for the years 2000-2003. Using meta-regression, we examined how this association was modified by season- and community-specific PM(2.5) composition, controlling for seasonal temperature as a surrogate for ventilation.

RESULTS

For a 10 microg/m3 increase in 2-day averaged PM(2.5) concentration we found an increase of 1.89% (95% CI: 1.34- 2.45) in CVD, 2.25% (95% CI: 1.10- 3.42) in MI, 1.85% (95% CI: 1.19- 2.51) in CHF, 2.74% (95% CI: 1.30- 4.2) in diabetes, and 2.07% (95% CI: 1.20- 2.95) in respiratory admissions. The association between PM2.5 and CVD admissions was significantly modified when the mass was high in Br, Cr, Ni, and Na(+), while mass high in As, Cr, Mn, OC, Ni, and Na(+) modified MI, and mass high in As, OC, and SO(4)(2-) modified diabetes admissions. For these species, an interquartile range increase in their relative proportion was associated with a 1-2% additional increase in daily admissions per 10 microg/m(3) increase in mass.

CONCLUSIONS

We found that PM(2.5) mass higher in Ni, As, and Cr, as well as Br and OC significantly increased its effect on hospital admissions. This result suggests that particles from industrial combustion sources and traffic may, on average, have greater toxicity.

The association between fine particulate air pollution and hospital emergency room visits for cardiovascular diseases in Beijing, China

BACKGROUND

Because epidemiological studies have yielded different results, the association between exposure to fine particulate matter less than 2.5 microm in aerodynamic diameter (PM(2.5)) and acute events of cardiovascular diseases (CVD) is unknown. Additionally, no research has been conducted to explore the association between PM(2.5) and hospital emergency room (ER) visits of cardiovascular diseases in Beijing, China.

OBJECTIVE

To explore the association between PM(2.5) and the hospital ER visits in Beijing, China for CVD {(International Classification of Diseases, 10th vision (ICD-10): I00-I99)}.

METHODS

We collected data for daily hospital ER visits for CVD from the Peking University Third Hospital, daily ambient PM(2.5) data from a fixed monitor site at Peking University, and data on the daily level of gaseous air pollutants {sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2))} from the Beijing Municipal Environmental Monitoring Center between June 1, 2004 and December 31, 2006. A time-stratified case-crossover design was used to evaluate associations between CVD health outcomes and ambient air pollutants.

RESULTS

8377 hospital ER visits of CVD were collected in our study. After adjusting the temperature and the relative humidity, the associations for 10 microg/m(3) increases in levels of PM(2.5), SO(2), or NO(2) and hospital ER visits for cardiovascular diseases were statistically significant with odds ratios (ORs) of 1.005{95% confidence interval (CI): 1.001-1.009}, 1.014(95% CI: 1.004-1.024), and 1.016(95% CI: 1.003-1.029), respectively.

CONCLUSION

These findings suggest that elevated levels of ambient air pollutants are associated with the increase in hospital ER visits for CVD in Beijing, China.

Air pollution exposure and self-reported cardiovascular disease

BACKGROUND

Studies suggest that increases of fine particle concentrations (PM2.5) could be linked with a rise in cardiovascular disease. With approximately 25% of American adults aged 30 and older reporting having either heart disease or hypertension it is possible that exposure to air pollution could have significant public health consequences. This study examined the relationship between PM2.5 and the prevalence of self-reported hypertension and heart disease using data from a large nation-wide survey.

STUDY DESIGN

Adults, 30 years of age or older, who participated in the National Health Interview Survey (NHIS) from 1999 to 2005 were linked to annual PM2.5 data from the US Environmental Protection Agency (N = 132,224). Annual air quality estimates were averaged from monitors within 20 miles of the respondent's residential block group. Respondents who reported being told they had hypertension by a health professional on two or more separate occasions were defined as hypertensive. Heart disease was defined as answering, "yes" to one or more of three NHIS questions on heart disease.

RESULTS

A 10 microg/m3 increase in PM2.5 exposure was associated with a small elevated risk of hypertension (adjusted odds ratio (OR) 1.05, 95% confidence interval (CI) 1.00-1.10) risk of heart disease (1.08 95% CI 1.00-1.16). The association between PM2.5 and hypertension was found in non-Hispanic white adults (OR 1.10 95% CI 1.04-1.17) but not in non-Hispanic black or Hispanic adults.

CONCLUSIONS

Findings from this study complement those from other studies and indicate that PM2.5 adversely affects cardiovascular health. Our results are consistent with other studies in showing a small association between exposure to PM2.5 and cardiovascular outcomes.

Effects of particulate matter (PM(10), PM(2.5) and PM(1)) on the cardiovascular system

Several studies have demonstrated that exposure to particulate matter (PM) of different size fractions is associated with an increased risk of cardiovascular disease (CVD). In this review, we have taken into consideration the possible correlation between the "short term" and "long term" effects of PM exposure and the onset of CVDs as well as the possible molecular mechanisms by which PM elicits the development of these events. Particularly, it is here underlined that these adverse health effects depend not only on the level of PM concentration in the air but also on its particular internal composition. Furthermore, we have also synthesized the findings gleaned from those few studies indicating that PM produced by tobacco smoke can give rise to cardiovascular injury.

Association between PM10 and O3 levels and hospital visits for cardiovascular diseases in Bangkok, Thailand

Background

The association between air pollution and cardiovascular diseases is well known, but previous studies only assessed mortality and hospital admissions in North America, Europe, and Northeast Asia. Few studies have been conducted in less-developed countries in regions with a tropical climate. This study evaluated whether short-term exposures to fine particulate matter (PM₁₀) and ozone (O₃) were associated with hospital visits for cardiovascular diseases (CVD; ICD-10th, I00–I99) in central Bangkok, Thailand.

Methods

Data from hospital records were obtained from 3 major government hospitals. All hospital visits were stratified by age group and category of CVD. Daily PM₁₀ and O₃ levels reported by the Pollution Control Department from April 2002 to December 2006 (1736 days) were used in a time-series analysis with a generalized additive model procedure.

Results

Exposure on the previous day to PM₁₀ and O₃ had a positive association with hospital visits for CVD among elderly (≥65 years) individuals. The increase in CVD hospital visits in this age group was 0.10% (95% CI, 0.03–0.19) with a 10 µg/m³ increase in PM₁₀, and 0.50% (95% CI, 0.19–0.81) with an increase in O₃.

Conclusions

In central Bangkok, a short-term association was observed between increases in daily levels of PM₁₀ and O₃ and the number of daily emergency hospital visits for CVD, particularly among individuals aged ≥65 years.

Particulate air pollution and chronic ischemic heart disease in the eastern United States: a county level ecological study using satellite aerosol data

BACKGROUND

There are several known factors that cause ischemic heart disease. However, the part played by air pollution still remains something of a mystery. Recent attention has focused on the chronic effect of particulate matter on heart disease. Satellite-derived aerosol optical depth (AOD) was found to be correlated with PM2.5 in the eastern US. The objective of this study was to examine if there is an association between aerosol air pollution as indicated by AOD and chronic ischemic heart disease (CIHD) in the eastern US.

METHODS

An ecological geographic study method was employed. Race and age standardized mortality rate (SMR) of CIHD was computed for each of the 2306 counties for the time period 2003-2004. A mean AOD raster grid for the same period was derived from Moderate Resolution Imaging Spectrometer (MODIS) aerosol data and the average AOD was calculated for each county. A bivariate Moran's I scatter plot, a map of local indicator of spatial association (LISA) clusters, and three regression models (ordinary least square, spatial lag, and spatial error) were used to analyze the relationship between AOD and CIHD SMR.

RESULTS

The global Moran's I value is 0.2673 (p = 0.001), indicating an overall positive spatial correlation of CIHD SMR and AOD. The entire study area is dominated by spatial clusters of AOD against SMR (high AOD and high SMR in the east, and low AOD and low SMR in the west) (permutations = 999, p = 0.05). Of the three regression models, the spatial error model achieved the best fit (R2 = 0.28). The effect of AOD is positive and significant (beta = 0.7774, p = 0.01).

CONCLUSION

Aerosol particle pollution has adverse effect on CIHD mortality risk in the eastern US. High risk of CIHD mortality was found in areas with elevated levels of outdoor aerosol air pollution as indicated by satellite derived AOD. The evidence of the association would support targeting of policy interventions on such areas to reduce air pollution levels. Remote sensing AOD data could be used as an alternative health-related indictor of air quality.

Traffic-generated air pollution and myocardial infarction

BACKGROUND

Although long-term air pollution exposure has been linked to cardiovascular mortality, data on incidence and nonfatal coronary disease are limited and inconclusive. The aim of this study was to investigate the association between long-term residential exposure to air pollution from traffic and the risk of nonfatal and fatal myocardial infarction.

METHODS

The records of all individuals aged 15 to 79 with a first event of myocardial infarction in Stockholm County during 1985 to 1996 were retrieved from a registry. Population controls were randomly selected from the study base stratified by age, sex, and calendar year. Individual socioeconomic data and home addresses were obtained from population censuses 1970 to 1995. Annual air pollution exposure was assessed by dispersion modeling at the home addresses of 24,347 cases and 276,926 controls.

RESULTS

Five-year average traffic-generated air pollution exposure corresponding to a difference in nitrogen dioxide from the fifth to the 95th percentile (31 microg/m) was associated with an odds ratio for fatal myocardial infarction adjusted for age, sex, calendar year, and socioeconomic status of 1.23 (95% confidence interval [CI] = 1.15-1.32). The corresponding odds ratio was 2.54 (1.96-3.29) among those with least expected misclassification of true individual exposure (those who did not move between censuses). Different time-windows and analyses of other pollutants including carbon monoxide and particles less than 10 mum in diameter (PM10) produced weaker associations. There was no increased risk for nonfatal myocardial infarction (ORs 0.94-0.98).

CONCLUSIONS

Long-term exposure to traffic-generated air pollution is associated with fatal myocardial infarction but not with nonfatal infarction.

Spatial analysis of MODIS aerosol optical depth, PM2.5, and chronic coronary heart disease

Background

Numerous studies have found adverse health effects of acute and chronic exposure to fine particulate matter (PM_2.5). Air pollution epidemiological studies relying on ground measurements provided by monitoring networks are often limited by sparse and unbalanced spatial distribution of the monitors. Studies have found correlations between satellite aerosol optical depth (AOD) and PM_2.5 in some land regions. Satellite aerosol data may be used to extend the spatial coverage of PM_2.5 exposure assessment. This study was to investigate correlation between PM_2.5 and AOD in the conterminous USA, to derive a spatially complete PM_2.5 surface by merging satellite AOD data and ground measurements based on the potential correlation, and to examine if there is an association of coronary heart disease with PM_2.5.

Results

Years 2003 and 2004 daily MODIS (Moderate Resolution Imaging Spectrometer) Level 2 AOD images were collated with US EPA PM_2.5 data covering the conterminous USA. Pearson's correlation analysis and geographically weighted regression (GWR) found that the relationship between PM_2.5 and AOD is not spatially consistent across the conterminous states. The average correlation is 0.67 in the east and 0.22 in the west. GWR predicts well in the east and poorly in the west. The GWR model was used to derive a PM_2.5 grid surface using the mean AOD raster calculated using the daily AOD data (RMSE = 1.67 μg/m³). Fitting of a Bayesian hierarchical model linking PM_2.5 with age-race standardized mortality rates (SMRs) of chronic coronary heart disease found that areas with higher values of PM_2.5 also show high rates of CCHD mortality: = 0.802, posterior 95% Bayesian credible interval (CI) = (0.386, 1.225).

Conclusion

There is a spatial variation of the relationship between PM_2.5 and AOD in the conterminous USA. In the eastern USA where AOD correlates well with PM_2.5, AOD can be merged with ground PM_2.5 data to derive a PM_2.5 surface for epidemiological study. The study found that chronic coronary heart disease mortality rate increases with exposure to PM_2.5.

Using urban man-made ponds to reconstruct a 150-year history of air pollution in northwest England

A regional pollution history has been reconstructed for the borough of Halton (northwest England) from four urban ponds in north Cheshire and south Merseyside, using environmental analyses of lake sediment stratigraphies. Mineral magnetism, geochemistry and radiometric dating have produced profiles of pollution characteristics dating from the mid-nineteenth century to present day. These pollution profiles reflect the atmospheric deposition of a range of pollutants over 150 years of intensified industry. Distinct phases of pollution deposition and characteristics are identified reflecting: (1) intensification of industry in the nineteenth century; (2) expansion of industry during the twentieth century; (3) post 1956 Clean Air Acts. This work promotes the potential use of these pollution archives for use in epidemiology to better understand links between human health and environmental pollution, especially for diseases with long latency times, where retrospective pollution exposure assessments are important.

Magneto-biomonitoring of intra-urban spatial variations of particulate matter using tree leaves

Preliminary mineral magnetic results from a pilot project investigating the suitability of roadside tree leaves as depositories of vehicular pollution are presented. Tree leaf surfaces (Lime: Tilia europaea; Sycamore: Acer pseudoplatanus) at four roadside and one woodland location in Wolverhampton, UK, have been monitored (July 2003 to November 2003). Mineral magnetic technologies have revealed spatial variations of particulate pollution concentration throughout the conurbation and data analysis indicates that magnetic concentration parameters are suitable proxies for fine particulate pollution, which are particularly hazardous to health. Site-specific traffic management and associated vehicle behaviour appear to be chiefly responsible for the magnetic concentration differences between sites. Magneto-biomonitoring in this way allows the high-resolution spatial mapping of particulate matter (PM) pollution, which may also benefit epidemiology in better assessing exposure to vehicular-derived particulates. Given the speed, measurement sensitivity and non-destructive nature of the technique, it is proposed that this low-cost approach offers some advantages over centralised monitoring stations to monitor urban roadside particulate pollution.

Estimating the health and economic benefits associated with reducing air pollution in the Barcelona metropolitan area (Spain)

OBJECTIVES

To estimate the health and economic benefits that would result from two scenarios of improved air quality in 57 municipalities of the metropolitan area of Barcelona.

METHODS

We used attributable fractions and life tables to quantify the benefits for selected health outcomes, based on published concentration-response functions and economic unit values. The mean weighted concentration of PM(10) for the study population was estimated through concentration surface maps developed by the local government.

RESULTS

The annual mean health benefits of reducing the mean PM(10) exposure estimated for the population in the study area (50microg/m(3)) to the annual mean value recommended by the World Health Organization (20microg/m(3)) were estimated to be 3,500 fewer deaths (representing an average increase in life expectancy of 14 months), 1,800 fewer hospitalizations for cardio-respiratory diseases, 5,100 fewer cases of chronic bronchitis among adults, 31,100 fewer cases of acute bronchitis among children, and 54,000 fewer asthma attacks among children and adults. The mean total monetary benefits were estimated to be 6,400 million euros per year. Reducing PM(10) to comply with the current European Union regulatory annual mean level (40microg/m(3)) would yield approximately one third of these benefits.

CONCLUSIONS

This study shows that reducing air pollution in the metropolitan area of Barcelona would result in substantial health and economic benefits. The benefits are probably underestimated due to the assumptions made in this study. Assessment of the health impact of local air pollution is a useful tool in public health.

Associations between PM2.5 and heart rate variability are modified by particle composition and beta-blocker use in patients with coronary heart disease

BACKGROUND

It has been hypothesized that ambient particulate air pollution is able to modify the autonomic nervous control of the heart, measured as heart rate variability (HRV). Previously we reported heterogeneous associations between particulate matter with aerodynamic diameter < 2.5 microm (PM2.5) and HRV across three study centers.

OBJECTIVES

We evaluated whether exposure misclassification, effect modification by medication, or differences in particle composition could explain the inconsistencies.

METHODS

Subjects with coronary heart disease visited clinics biweekly in Amsterdam, the Netherlands; Erfurt, Germany; and Helsinki, Finland for 6-8 months. The standard deviation (SD) of NN intervals on an electrocardiogram (ECG; SDNN) and high frequency (HF) power of HRV was measured with ambulatory ECG during paced breathing. Outdoor levels of PM2.5 were measured at a central site. In Amsterdam and Helsinki, indoor and personal PM2.5 were measured during the 24 hr preceding the clinic visit. PM2.5 was apportioned between sources using principal component analyses. We analyzed associations of indoor/personal PM2.5, elements of PM2.5, and source-specific PM2.5 with HRV using linear regression.

RESULTS

Indoor and personal PM2.5 were not associated with HRV. Increased outdoor PM2.5 was associated with decreased SDNN and HF at lags of 2 and 3 days only among persons not using beta-blocker medication. Traffic-related PM2.5 was associated with decreased SDNN, and long-range transported PM2.5 with decreased SDNN and HF, most strongly among persons not using beta blockers. Indicators for PM2.5 from traffic and long-range transport were also associated with decreased HRV.

CONCLUSIONS

Our results suggest that differences in the composition of particles, beta-blocker use, and obesity of study subjects may explain some inconsistencies among previous studies on HRV.

Seasonal and regional short-term effects of fine particles on hospital admissions in 202 US counties, 1999-2005

The authors investigated whether short-term effects of fine particulate matter with an aerodynamic diameter < or =2.5 microm (PM(2.5)) on risk of cardiovascular and respiratory hospitalizations among the elderly varied by region and season in 202 US counties for 1999-2005. They fit 3 types of time-series models to provide evidence for 1) consistent particulate matter effects across the year, 2) different particulate matter effects by season, and 3) smoothly varying particulate matter effects throughout the year. The authors found statistically significant evidence of seasonal and regional variation in estimates of particulate matter effect. Respiratory disease effect estimates were highest in winter, with a 1.05% (95% posterior interval: 0.29, 1.82) increase in hospitalizations per 10-microg/m(3) increase in same-day PM(2.5). Cardiovascular diseases estimates were also highest in winter, with a 1.49% (95% confidence interval: 1.09, 1.89) increase in hospitalizations per 10-microg/m(3) increase in same-day PM(2.5), with associations also observed in other seasons. The strongest evidence of a relation between PM(2.5) and hospitalizations was in the Northeast for both respiratory and cardiovascular diseases. Heterogeneity of PM(2.5) effects on hospitalizations may reflect seasonal and regional differences in emissions and in particles' chemical constituents. Results can help guide development of hypotheses and further epidemiologic studies on potential heterogeneity in the toxicity of constituents of the particulate matter mixture.

Acute effects of ambient particulate matter on mortality in Europe and North America: results from the APHENA study

BACKGROUND

THE APHENA (AIR POLLUTION AND HEALTH: A Combined European and North American Approach) study is a collaborative analysis of multicity time-series data on the effect of air pollution on population health, bringing together data from the European APHEA (Air Pollution and Health: A European Approach) and U.S. NMMAPS (National Morbidity, Mortality and Air Pollution Study) projects, along with Canadian data.

OBJECTIVES

The main objective of APHENA was to assess the coherence of the findings of the multicity studies carried out in Europe and North America, when analyzed with a common protocol, and to explore sources of possible heterogeneity. We present APHENA results on the effects of particulate matter (PM) < or = 10 microm in aerodynamic diameter (PM(10)) on the daily number of deaths for all ages and for those < 75 and > or = 75 years of age. We explored the impact of potential environmental and socioeconomic factors that may modify this association.

METHODS

In the first stage of a two-stage analysis, we used Poisson regression models, with natural and penalized splines, to adjust for seasonality, with various degrees of freedom. In the second stage, we used meta-regression approaches to combine time-series results across cites and to assess effect modification by selected ecologic covariates.

RESULTS

Air pollution risk estimates were relatively robust to different modeling approaches. Risk estimates from Europe and United States were similar, but those from Canada were substantially higher. The combined effect of PM(10) on all-cause mortality across all ages for cities with daily air pollution data ranged from 0.2% to 0.6% for a 10-microg/m(3) increase in ambient PM(10) concentration. Effect modification by other pollutants and climatic variables differed in Europe and the United States. In both of these regions, a higher proportion of older people and higher unemployment were associated with increased air pollution risk.

CONCLUSIONS

Estimates of the increased mortality associated with PM air pollution based on the APHENA study were generally comparable with results of previous reports. Overall, risk estimates were similar in Europe and in the United States but higher in Canada. However, PM(10) effect modification patterns were somewhat different in Europe and the United States.

Air Pollution and Inflammatory Response in Myocardial Infarction Survivors: Gene–Environment Interactions in a High-Risk Group

Ambient air pollution has been associated with an increased risk of hospital admission and mortality in potentially susceptible subpopulations, including myocardial infarction (MI) survivors. The multicenter epidemiological study described in this report was set up to study the role of air pollution in eliciting inflammation in MI survivors in six European cities, Helsinki, Stockholm, Augsburg, Rome, Barcelona, and Athens. Outcomes of interest are plasma concentrations of the proinflammatory cytokine interleukin 6 (IL-6) and the acute-phase proteins C-reactive protein (CRP) and fibrinogen. In addition, the study was designed to assess the role of candidate gene polymorphisms hypothesized to lead to a modification of the short-term effects of ambient air pollution. In total, 1003 MI survivors were recruited and assessed with at least 2 repeated clinic visits without any signs of infections. In total, 5813 blood samples were collected, equivalent to an average of 5.8 repeated clinic visits per subject (97% of the scheduled 6 repeated visits). Subjects across the six cities varied with respect to risk factor profiles. Most of the subjects were nonsmokers, but light smokers were included in Rome, Barcelona, and Athens. Substantial inter- and intraindividual variability was observed for IL-6 and CRP. The study will permit assessing the role of cardiovascular disease risk factors, including ambient air pollution and genetic polymorphisms in candidate genes, in determining the inter- and the intraindividual variability in plasma IL-6, CRP, and fibrinogen concentrations in MI survivors.

Differences in heart rate variability associated with long-term exposure to NO2

BACKGROUND

Heart rate variability (HRV), a measure of cardiac autonomic tone, has been associated with cardiovascular morbidity and mortality. Short-term studies have shown that subjects exposed to higher traffic-associated air pollutant levels have lower HRV.

OBJECTIVE

Our objective was to investigate the effect of long-term exposure to nitrogen dioxide on HRV in the Swiss cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA).

METHODS

We recorded 24-hr electrocardiograms in randomly selected SAPALDIA participants >or= 50 years of age. Other examinations included an interview investigating health status and measurements of blood pressure, body height, and weight. Annual exposure to NO2 at the address of residence was predicted by hybrid models (i.e., a combination of dispersion predictions, land-use, and meteorologic parameters). We estimated the association between NO2 and HRV in multivariable linear regression models. Complete data for analyses were available for 1,408 subjects.

RESULTS

For women, but not for men, each 10-microg/m3 increment in 1-year averaged NO2 level was associated with a decrement of 3% (95% CI, -4 to -1) for the standard deviation of all normal-to-normal RR intervals (SDNN), -6% (95% CI, -11 to -1) for nighttime low frequency (LF), and -5% (95% CI, -9 to 0) for nighttime LF/high-frequency (HF) ratio. We saw no significant effect for 24-hr total power (TP), HF, LF, or LF/HF or for nighttime SDNN, TP, or HF. In subjects with self-reported cardiovascular problems, SDNN decreased by 4% (95% CI, -8 to -1) per 10-microg/m3 increase in NO2.

CONCLUSIONS

There is some evidence that long-term exposure to NO2 is associated with cardiac autonomic dysfunction in elderly women and in subjects with cardiovascular disease.

Airborne particulate matter and human health: toxicological assessment and importance of size and composition of particles for oxidative damage and carcinogenic mechanisms

Air pollution has been considered a hazard to human health. In the past decades, many studies highlighted the role of ambient airborne particulate matter (PM) as an important environmental pollutant for many different cardiopulmonary diseases and lung cancer. Numerous epidemiological studies in the past 30 years found a strong exposure-response relationship between PM for short-term effects (premature mortality, hospital admissions) and long-term or cumulative health effects (morbidity, lung cancer, cardiovascular and cardiopulmonary diseases, etc). Current research on airborne particle-induced health effects investigates the critical characteristics of particulate matter that determine their biological effects. Several independent groups of investigators have shown that the size of the airborne particles and their surface area determine the potential to elicit inflammatory injury, oxidative damage, and other biological effects. These effects are stronger for fine and ultrafine particles because they can penetrate deeper into the airways of the respiratory tract and can reach the alveoli in which 50% are retained in the lung parenchyma. Composition of the PM varies greatly and depends on many factors. The major components of PM are transition metals, ions (sulfate, nitrate), organic compound, quinoid stable radicals of carbonaceous material, minerals, reactive gases, and materials of biologic origin. Results from toxicological research have shown that PM have several mechanisms of adverse cellular effects, such as cytotoxicity through oxidative stress mechanisms, oxygen-free radical-generating activity, DNA oxidative damage, mutagenicity, and stimulation of proinflammatory factors. In this review, the results of the most recent epidemiological and toxicological studies are summarized. In general, the evaluation of most of these studies shows that the smaller the size of PM the higher the toxicity through mechanisms of oxidative stress and inflammation. Some studies showed that the extractable organic compounds (a variety of chemicals with mutagenic and cytotoxic properties) contribute to various mechanisms of cytotoxicity; in addition, the water-soluble faction (mainly transition metals with redox potential) play an important role in the initiation of oxidative DNA damage and membrane lipid peroxidation. Associations between chemical compositions and particle toxicity tend to be stronger for the fine and ultrafine PM size fractions. Vehicular exhaust particles are found to be most responsible for small-sized airborne PM air pollution in urban areas. With these aspects in mind, future research should aim at establishing a cleared picture of the cytotoxic and carcinogenic mechanisms of PM in the lungs, as well as mechanisms of formation during internal engine combustion processes and other sources of airborne fine particles of air pollution.

A 10-year time-series analysis of respiratory and cardiovascular morbidity in Nicosia, Cyprus: the effect of short-term changes in air pollution and dust storms

BACKGROUND

To date, a substantial body of research has shown adverse health effects of short-term changes in levels of air pollution. Such associations have not been investigated in smaller size cities in the Eastern Mediterranean. A particular feature in the region is dust blown from the Sahara a few times a year resulting in extreme PM10 concentrations. It is not entirely clear whether such natural phenomena pose the same risks.

METHODS

The effect of changes in daily levels of particulate matter (PM10) and ozone (O3) on hospitalization for all, cardiovascular and respiratory causes in the two hospitals in Nicosia during 1 January 1995 and 30 December 2004 was investigated using generalized additive Poisson models after controlling for long- and short-term patterns as well as for the effect of weather. Meteorological records were reviewed to identify dust-storm days and analyses were repeated to quantify their effect on cardio-respiratory morbidity.

RESULTS

For every 10 microg/m3 increase in daily average PM10 concentrations, there was a 0.9% (95%CI: 0.6%, 1.2%) increase in all-cause and 1.2% (95%CI: -0.0%, 2.4%) increase in cardiovascular admissions. With respect to respiratory causes, an effect was observed only in the warm months. No lagged effects with levels of PM10 were observed. In contrast, positive associations with levels of ozone were only observed the two days prior to admission. These appeared stronger for cardiovascular causes and independent of the effect of PM. All-cause and cardiovascular admissions were 4.8% (95%CI: 0.7%, 9.0%) and 10.4% (95%CI: -4.7%, 27.9%) higher on dust storm days respectively. In both cases the magnitude of effect was comparable to that seen on the quartile of non-storm days with the highest levels of PM10.

CONCLUSION

We observed an increased risk of hospitalization at elevated levels of particulate matter and ozone generally consistent with the magnitude seen across several European cities. We also observed an increased risk of hospitalization on dust storm days, particularly for cardiovascular causes. While inference from these associations is limited due to the small number of dust storm days in the study period, it would appear imperative to issue health warnings for these natural events, particularly directed towards vulnerable population groups.

Spatial variations in estimated chronic exposure to traffic-related air pollution in working populations: a simulation

Background

Chronic exposure to traffic-related air pollution is associated with a variety of health impacts in adults and recent studies show that exposure varies spatially, with some residents in a community more exposed than others. A spatial exposure simulation model (SESM) which incorporates six microenvironments (home indoor, work indoor, other indoor, outdoor, in-vehicle to work and in-vehicle other) is described and used to explore spatial variability in estimates of exposure to traffic-related nitrogen dioxide (not including indoor sources) for working people. The study models spatial variability in estimated exposure aggregated at the census tracts level for 382 census tracts in the Greater Vancouver Regional District of British Columbia, Canada. Summary statistics relating to the distributions of the estimated exposures are compared visually through mapping. Observed variations are explored through analyses of model inputs.

Results

Two sources of spatial variability in exposure to traffic-related nitrogen dioxide were identified. Median estimates of total exposure ranged from 8 μg/m³ to 35 μg/m³ of annual average hourly NO₂ for workers in different census tracts in the study area. Exposure estimates are highest where ambient pollution levels are highest. This reflects the regional gradient of pollution in the study area and the relatively high percentage of time spent at home locations. However, for workers within the same census tract, variations were observed in the partial exposure estimates associated with time spent outside the residential census tract. Simulation modeling shows that some workers may have exposures 1.3 times higher than other workers residing in the same census tract because of time spent away from the residential census tract, and that time spent in work census tracts contributes most to the differences in exposure. Exposure estimates associated with the activity of commuting by vehicle to work were negligible, based on the relatively short amount of time spent in this microenvironment compared to other locations. We recognize that this may not be the case for pollutants other than NO_2. These results represent the first time spatially disaggregated variations in exposure to traffic-related air pollution within a community have been estimated and reported.

Conclusion

The results suggest that while time spent in the home indoor microenvironment contributes most to between-census tract variation in estimates of annual average exposures to traffic-related NO₂, time spent in the work indoor microenvironment contributes most to within-census tract variation, and time spent in transit by vehicle makes a negligible contribution. The SESM has potential as a policy evaluation tool, given input data that reflect changes in pollution levels or work flow patterns due to traffic demand management and land use development policy.

Environmental risk factors for heart disease

In this review, we discuss current evidence linking environmental pollutants to cardiovascular disease (CVD). Extensive evidence indicates that environmental factors contribute to CVD risk, incidence, and severity. Migrant studies show that changes in the environment could substantially alter CVD risk in a genetically stable population. Additionally, CVD risk is affected by changes in nutritional and lifestyle choices. Recent studies in the field of environmental cardiology suggest that environmental toxins also influence CVD. Exposure to tobacco smoke is paradigmatic of such environmental risk and is strongly and positively associated with increased cardiovascular morbidity and mortality. In animal models of exposure, tobacco smoke induces endothelial dysfunction and prothrombotic responses and exacerbates atherogenesis and myocardial ischemic injury. Similar mechanism may be engaged by other pollutants or food constituents. Several large population-based studies indicate that exposure to fine or ultrafine particulate air pollution increases CVD morbidity and mortality, and the plausibility of this association is supported by data from animal studies. Exposure to other chemicals such as polyaromatic hydrocarbons, aldehydes, and metals has also been reported to elevate CVD risk by affecting atherogenesis, thrombosis, or blood pressure regulation. Maternal exposure to drugs, toxins, and infection has been linked with cardiac birth defects and premature CVD in later life. Collectively, the data support the notion that chronic environmental stress is an important determinant of CVD risk. Further work is required to assess the magnitude of this risk fully and to delineate specific mechanisms by which environmental toxins affect CVD.

Valuing the health benefits of improving indoor air quality in residences

Unlike commercial premises, the indoor air quality of residences is more dynamic, uncontrolled, and prone to human behavioral changes. In consequence, measuring the health benefit gains derived from improving indoor air quality in residences is more complicated. To overcome this, a human thermal comfort model was first integrated with indoor microenvironment models, and subsequently linked with appropriate concentration-response and economic data for estimating the economic benefit gains derived from improving indoor air quality in residences for an adult and an elderly person. In this study, the development of the model is illustrated by using a typical residential apartment locating at the worst air quality neighborhood in Hong Kong and the daily weather profiles between 2002 and 2006. Three types of personal intervention measures were examined in the study: (i) using air cleaner in residence, (ii) changing time spent in residence, and (iii) relocating to a better air quality neighborhood. Our results revealed that employing air cleaners with windows closed in residence throughout the entire year was the most beneficial measure as it could provide the greatest annual health benefit gains. It would give a maximum of HK$2072 in 5-year cumulative benefit gain for an adult and HK$1700 for an elderly person. Employing air cleaners with windows closed in only cool season (October through March) could give the highest marginal return per dollar spent. The benefit gains would become smaller when windows were opened to a greater extent. By contrast, relocating to a better air quality neighborhood and changing the time spent in residence did not appeal to be beneficial intervention measures.

Effect of short-term exposure to air pollution and pollen on medical emergency calls: a case-crossover study in Spain

BACKGROUND

A symmetric case-crossover design was used to analyse the short-term relationship between air pollution, pollen and emergency calls to medical services.

METHODS

This study covered patients who made medical emergency calls in the City of Vigo (Spain) during the period 1996-1999. Morbidity data were obtained from the records of the 061 Medical Emergency Control Center, in its capacity as the body officially coordinating all medical emergencies by telephone. Air pollution data were furnished by the Vigo Municipal Air Pollution Surveillance Grid. Pollen levels were provided by the staff of the Spanish Aerobiology Network in Vigo.

RESULTS

A rise of 10 microg/m(3) in ambient particulate levels led to the risk of medical emergency calls requesting attention increasing by: (i) 1.97% [95% confidence interval (95% CI): 1.83-2.11%] for circulatory causes on the same day; (ii) 1.95% (95% CI: 1.76-2.14%) for respiratory causes at 2 days and (iii) 1.34% (95% CI: 1.23-1.45%) for combined circulatory and respiratory causes on the same day. A number of pollens displayed a statistically significant relationship with emergency calls. No interaction was in evidence between pollens and air pollutants.

CONCLUSIONS

While elevations in particulate air pollution increase medical emergency calls because of cardiac or respiratory causes or both combined, elevations in pollen levels increase medical emergency calls because of respiratory causes.

Mortality and life expectancy of Yokkaichi asthma patients, Japan: late effects of air pollution in 1960-70s

BACKGROUND

The incidence of chronic obstructive pulmonary disease (COPD) and bronchial asthma began increasing in early 1960s in the population of Yokkaichi-city (Mie Prefecture, Japan). The cause of the disease was sulfur oxide air pollution, and it is known as Yokkaichi Asthma. The pollution markedly decreased by the end of 1970s; no new cases have been reported since 1988. This study aimed at examining the late effects of air pollution on the health of Yokkaichi Asthma patients.

METHODS

Mortality rate and life expectancy of patients, registered between 1965 and 1988, were investigated from 1975 through 2000.

RESULTS

Mortality rates for COPD and asthma in patients from Yokkaichi-city were significantly higher than in the whole population of Mie Prefecture. For all ages (except for males between 80 and 84 years in 1985), the life expectancy of both males and females were significantly reduced in patients from Yokkaichi-city as compared with the whole population of Mie Prefecture. The potential gains in life expectancy excluding the mortality for respiratory diseases including COPD and asthma were larger for all ages in patients from Yokkaichi-city.

CONCLUSION

Mortality and life expectancy were adversely affected in patients from Yokkaichi-city, despite the fact that the air pollution problem has been already solved.

Short-term exposure to air pollution and inflammation-sensitive biomarkers

OBJECTIVES

To evaluate the effect of short-term exposure to air pollutants on inflammation-sensitive biomarkers in apparently healthy individuals.

METHODS

We enrolled all participants from The Tel-Aviv Sourasky Medical Center inflammation survey held between 2003 and 2006, excluding participants with an acute or chronic inflammatory disease, pregnancy, steroidal or nonsteroidal treatment, or a recent invasive procedure. Additional subjects were excluded for living more than 11km from the nearest air pollution monitoring station. Analysis was performed separately for men and women. Linear regression models were fitted for each inflammatory variable against air pollutant variables (particulate matter under 10microm, sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone) for increasing lag times of up to 7 days, and adjusted for all possible and known confounding parameters.

RESULTS

The study population comprised 3659 individuals (2203 males and 1456 females). We found a statistically significant negative correlation in the male population between air pollutants, mainly NO2, SO2, and CO, and fibrinogen in several lag days. A positive correlation was found for PM10 at day 7. No such correlation was found for CRP and WBC, or for the female population.

CONCLUSION

Our findings do not support the potential link between short-term exposure to air pollution and enhanced inflammation as a possible explanation for increased cardiovascular morbidity. Additional large-scale population-based studies with good methodological design are needed in order to clarify this issue.

Effects of exposure measurement error on particle matter epidemiology: a simulation using data from a panel study in Baltimore, MD

Ascertaining the true risk associated with exposure to particulate matter (PM) is difficult, given the fact that pollutant components are frequently correlated with each other and with other gaseous pollutants; relationships between ambient concentrations and personal exposures are often not well understood; and PM, unlike its gaseous co-pollutants, does not represent a single chemical. In order to examine differences between observed versus true health risk estimate from epidemiologic studies, we conducted a simulation using data from a recent multi-pollutant exposure assessment study in Baltimore, MD. The objectives of the simulation were twofold: (a) to estimate the distribution of personal air pollutant exposures one might expect to observe within a population, given the corresponding ambient concentrations found in that location and; (b) using an assumed true health risk with exposure to one pollutant, to estimate the distribution of health risk estimates likely to be observed in an epidemiologic study using ambient pollutant concentrations as a surrogate of exposure as compared with actual personal pollutant exposures. Results from the simulations showed that PM2.5 was the only pollutant where a true association with its total personal exposures resulted in a significant observed association with its ambient concentrations. The simulated results also showed that true health risks associated with personal exposure to O3 and NO2 would result in no significant observed associations with any of their respective ambient concentrations. Conversely, a true association with PM2.5 would result in a significant, observed association with NO2 (beta=0.0115, 95% confidence interval (CI): 0.0056, 0.0185) and a true association with exposure to SO4(2-) would result in an observed significant association with O3 (beta=0.0035, 95% CI: 0.0021, 0.0051) given the covariance of the ambient pollutant concentrations. The results provide an indication that, in Baltimore during this study period, ambient gaseous concentrations may not have been adequate surrogates for corresponding personal gaseous exposures to allow the question to be investigated using central site monitors. Alternatively, the findings may suggest that in some locations, observed associations with the gaseous pollutants should be interpreted with caution, as they may be reflecting associations with PM or one of its chemical components.

Efficiency of two-phase methods with focus on a planned population-based case-control study on air pollution and stroke

BACKGROUND

We plan to conduct a case-control study to investigate whether exposure to nitrogen dioxide (NO2) increases the risk of stroke. In case-control studies, selective participation can lead to bias and loss of efficiency. A two-phase design can reduce bias and improve efficiency by combining information on the non-participating subjects with information from the participating subjects. In our planned study, we will have access to individual disease status and data on NO2 exposure on group (area) level for a large population sample of Scania, southern Sweden. A smaller sub-sample will be selected to the second phase for individual-level assessment on exposure and covariables. In this paper, we simulate a case-control study based on our planned study. We develop a two-phase method for this study and compare the performance of our method with the performance of other two-phase methods.

METHODS

A two-phase case-control study was simulated with a varying number of first- and second-phase subjects. Estimation methods: Method 1: Effect estimation with second-phase data only. Method 2: Effect estimation by adjusting the first-phase estimate with the difference between the adjusted and unadjusted second-phase estimate. The first-phase estimate is based on individual disease status and residential address for all study subjects that are linked to register data on NO2-exposure for each geographical area. Method 3: Effect estimation by using the expectation-maximization (EM) algorithm without taking area-level register data on exposure into account. Method 4: Effect estimation by using the EM algorithm and incorporating group-level register data on NO2-exposure.

RESULTS

The simulated scenarios were such that, unbiased or marginally biased (< 7%) odds ratio (OR) estimates were obtained with all methods. The efficiencies of method 4, are generally higher than those of methods 1 and 2. The standard errors in method 4 decreased further when the case/control ratio is above one in the second phase. For all methods, the standard errors do not become substantially reduced when the number of first-phase controls is increased.

CONCLUSION

In the setting described here, method 4 had the best performance in order to improve efficiency, while adjusting for varying participation rates across areas.

Ambient particle source apportionment and daily hospital admissions among children and elderly in Copenhagen

An association between particulate air pollution and morbidity and mortality is well established. However, little is known about which sources of particulate matter contribute most to the adverse health effects. Identification of responsible sources would merit more efficient control. For a 6-year period (01 January 1999 to 31 December 2004), we examined associations between urban background PM(10) in the presence of gaseous pollutants (CO, NO(2)) and hospital admissions due to cardiovascular and respiratory disease in the elderly (age>/=65), and asthma in children (age 5-18) in Copenhagen, Denmark. We further studied associations between fractions of PM(10) assigned to six sources (biomass, secondary, oil, crustal, sea salt, and vehicle) and admissions during a 1(1/2) -year campaign. We used Poisson generalized additive time-series model adjusted for season, day of the week, public holidays, influenza epidemics, grass pollen, school holidays, and meteorology, with up to 5 days lagged air pollution exposure. We found positive associations between PM(10) and the three health outcomes, with strongest associations for asthma. The PM(10) effect remained robust in the presence of CO and NO(2). We found different PM(10) sources to be variably associated with different outcomes: crustal and secondary sources showed strongest associations with cardiovascular, biomass with respiratory, and vehicle with asthma admissions. These novel results may merit future research of potential mechanism, whereas at present, no single PM(10) source can be attributed to all morbidity.

Short-term effects of air pollution on cardiovascular diseases: outcomes and mechanisms

The effects of air pollution on health have been intensively studied in recent years. Acute exposure to environmental pollutants such as particulate and gaseous matters (carbon monoxide, nitrogen oxides, sulphur dioxide and ozone) was associated with an increased rate of events and mortality because of cardiovascular diseases. These effects were investigated in short-term studies, which related day-to-day variations in air pollution to disease, and in long-term studies, which have followed cohorts of exposed individuals over time. The evidence from the literature on the short-term cardiovascular effects of air pollutants is discussed from clinical and mechanistic points of view.

Short-term effects of particulate matter: an inflammatory mechanism?

"Would you tell me please, which way I ought to go from here," asked Alice. "That depends a good deal on where you want to go to," said the cat. (Lewis Carroll, Alice's Adventures in Wonderland) A large number of epidemiological studies show positive correlations between increasing levels of particulate matter (PM) in urban air and short-term morbidity and mortality for diverse acute cardiopulmonary diseases. Brought about by PM increments, inflammation is thought to exacerbate preexisting inflammatory diseases. Experimental evidence suggests a hierarchical oxidative stress model, in which a weakened antioxidant defense, as observed in disease or induced by inhaled particles, increases the PM ability to cause lung inflammation, accounting for exacerbations that occur in asthmatics and in patients with chronic obstructive lung disease. The role of PM-induced inflammation leading to acute cardiovascular events such as arrhythmia, heart failure, and myocardial infarction is more speculative. There is neither clear-cut evidence in humans that inhaled PM could get as far as blood circulation nor that proinflammatory mediators are significantly released from inflamed lung tissues, nor that blood coagulability is critically altered. As a whole, data in humans indicate that short-term inflammatory responses to PM are not always detected; they are usually mild and loosely correlated with functional changes. Among these studies, the diversity of PM characteristics, dose metrics, and endpoints hampers a clear discerning of inflammatory mechanism(s). Thus, the question arises as to whether inflammation represents the mechanism of acute cardiopulmonary PM toxicities in susceptible individuals, or rather an event that may coexist with other relevant mechanism(s). This review article discusses the evidence in humans linking short-term PM increments to inflammation and to exacerbations of cardiopulmonary diseases. Although there is a large amount of data available, there still remains a gulf between the number of epidemiological and panel studies and that of controlled exposures. Research on controlled exposure needs expanding, so that the results of time-series and panel studies will be better understood and short-term standards for human exposure may be more confidently allocated.

Endothelial function and chronic exposure to air pollution in normal male subjects

Exposure to urban air pollution, ultrafine particles or gases, is associated with acute cardiovascular mortality and morbidity. We investigated the effect of ambient air pollution on endothelial function in 40 healthy white male nonsmokers spontaneously breathing ambient air in Paris, France. Air pollutant levels (nitrogen, sulfur and carbon oxides, and particulate matter) were averaged during the 5 days preceding arterial measurements. Brachial artery endothelium-dependent flow-mediated dilatation and reactive hyperemia induced by hand ischemia and endothelium-independent glyceryl trinitrate dilatation were measured using a radiofrequency-based echo-tracking device at 2-week intervals. Flow-mediated dilatation was independently and negatively correlated with the average levels of sulfur dioxide (P<0.001) and nitrogen monoxide (P<0.01). Sulfur dioxide levels explained 19% of the variance of flow-mediated dilatation. An increase in gaseous pollutants, 2 weeks apart, was significantly associated with a decreased in flow-mediated dilatation. No association was found between air pollutants and glyceryl trinitrate-induced vasodilatation. Reactive hyperemia was significantly and positively correlated with particulate matter with aerodynamic diameters <10 microm and <2.5 microm (P<0.0001 and P<0.001, respectively) and nitrogen dioxide (P<0.01). An increase in particulate matter, 2 weeks apart, was significantly correlated with an increase in reactive hyperemia. Endothelial function was impaired by ordinary levels of pollution in healthy young males, in an urban area, and may be reduced by 50% between the least and the most polluted day. Gaseous pollutants affect large artery endothelial function, whereas particulate matter exaggerates the dilatory response of small arteries to ischemia.

Ambient biomass smoke and cardio-respiratory hospital admissions in Darwin, Australia

BACKGROUND

Increasing severe vegetation fires worldwide has been attributed to both global environmental change and land management practices. However there is little evidence concerning the population health effects of outdoor air pollution derived from biomass fires. Frequent seasonal bushfires near Darwin, Australia provide an opportunity to examine this issue. We examined the relationship between atmospheric particle loadings <10 microns in diameter (PM10), and emergency hospital admissions for cardio-respiratory conditions over the three fire seasons of 2000, 2004 and 2005. In addition we examined the differential impacts on Indigenous Australians, a high risk population subgroup.

METHODS

We conducted a case-crossover analysis of emergency hospital admissions with principal ICD10 diagnosis codes J00-J99 and I00-I99. Conditional logistic regression models were used to calculate odds ratios for admission with 10 microg/m3 rises in PM10. These were adjusted for weekly influenza rates, same day mean temperature and humidity, the mean temperature and humidity of the previous three days, days with rainfall > 5 mm, public holidays and holiday periods.

RESULTS

PM10 ranged from 6.4 - 70.0 microg/m3 (mean 19.1). 2466 admissions were examined of which 23% were for Indigenous people. There was a positive relationship between PM10 and admissions for all respiratory conditions (OR 1.08 95%CI 0.98-1.18) with a larger magnitude in the Indigenous subpopulation (OR1.17 95% CI 0.98-1.40). While there was no relationship between PM10 and cardiovascular admissions overall, there was a positive association with ischaemic heart disease in Indigenous people, greatest at a lag of 3 days (OR 1.71 95%CI 1.14-2.55).

CONCLUSION

PM10 derived from vegetation fires was predominantly associated with respiratory rather than cardiovascular admissions. This outcome is consistent with the few available studies of ambient biomass smoke pollution. Indigenous people appear to be at higher risk of cardio-respiratory hospital admissions associated with exposure to PM10.

Ambient biomass smoke and cardio-respiratory hospital admissions in Darwin, Australia

BACKGROUND

Increasing severe vegetation fires worldwide has been attributed to both global environmental change and land management practices. However there is little evidence concerning the population health effects of outdoor air pollution derived from biomass fires. Frequent seasonal bushfires near Darwin, Australia provide an opportunity to examine this issue. We examined the relationship between atmospheric particle loadings <10 microns in diameter (PM10), and emergency hospital admissions for cardio-respiratory conditions over the three fire seasons of 2000, 2004 and 2005. In addition we examined the differential impacts on Indigenous Australians, a high risk population subgroup.

METHODS

We conducted a case-crossover analysis of emergency hospital admissions with principal ICD10 diagnosis codes J00-J99 and I00-I99. Conditional logistic regression models were used to calculate odds ratios for admission with 10 microg/m3 rises in PM10. These were adjusted for weekly influenza rates, same day mean temperature and humidity, the mean temperature and humidity of the previous three days, days with rainfall > 5 mm, public holidays and holiday periods.

RESULTS

PM10 ranged from 6.4 - 70.0 microg/m3 (mean 19.1). 2466 admissions were examined of which 23% were for Indigenous people. There was a positive relationship between PM10 and admissions for all respiratory conditions (OR 1.08 95%CI 0.98-1.18) with a larger magnitude in the Indigenous subpopulation (OR1.17 95% CI 0.98-1.40). While there was no relationship between PM10 and cardiovascular admissions overall, there was a positive association with ischaemic heart disease in Indigenous people, greatest at a lag of 3 days (OR 1.71 95%CI 1.14-2.55).

CONCLUSION

PM10 derived from vegetation fires was predominantly associated with respiratory rather than cardiovascular admissions. This outcome is consistent with the few available studies of ambient biomass smoke pollution. Indigenous people appear to be at higher risk of cardio-respiratory hospital admissions associated with exposure to PM10.

Daily mortality and particulate matter in different size classes in Erfurt, Germany

The link between elevated concentrations of ambient particulate matter (PM) and increased mortality has been investigated in numerous studies. Here we analyzed the role of different particle size fractions with respect to total and cardio-respiratory mortality in Erfurt, Germany, between 1995 and 2001. Number concentrations (NC) of PM were measured using an aerosol spectrometer consisting of a Differential Mobility Particle Sizer and a Laser Aerosol Spectrometer to characterize particles between 0.01 and 0.5 and between 0.1 and 2.5 microm, respectively. We derived daily means of particle NC for ultrafine (0.01-0.1 microm) and for fine particles (0.01-2.5 microm). Assuming spherical particles of a constant density, we estimated the mass concentrations (MC) of particles in these size ranges. Concurrently, data on daily total and cardio-respiratory death counts were obtained from local health authorities. The data were analyzed using Poisson Generalized Additive Models adjusting for trend, seasonality, influenza epidemics, day of the week, and meteorology using smooth functions or indicator variables. We found statistically significant associations between elevated ultrafine particle (UFP; diameter: 0.01-0.1 microm) NC and total as well as cardio-respiratory mortality, each with a 4 days lag. The relative mortality risk (RR) for a 9748 cm(-3) increase in UFP NC was RR=1.029 and its 95% confidence interval (CI)=1.003-1.055 for total mortality. For cardio-respiratory mortality we found: RR=1.031, 95% CI: 1.003-1.060. No association between fine particle MC and mortality was found. This study shows that UFP, representing fresh combustion particles, may be an important component of urban air pollution associated with health effects.

Cause-specific mortality in the unionized U.S. trucking industry

BACKGROUND

Occupational and population-based studies have related exposure to fine particulate air pollution, and specifically particulate matter from vehicle exhausts, to cardiovascular diseases and lung cancer.

OBJECTIVES

We have established a large retrospective cohort to assess mortality in the unionized U.S. trucking industry. To provide insight into mortality patterns associated with job-specific exposures, we examined rates of cause-specific mortality compared with the general U.S. population.

METHODS

We used records from four national trucking companies to identify 54,319 male employees employed in 1985. Cause-specific mortality was assessed through 2000 using the National Death Index. Expected numbers of all and cause-specific deaths were calculated stratifying by race, 10-year age group, and calendar period using U.S. national reference rates. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were calculated for the entire cohort and by job title.

RESULTS

As expected in a working population, we found a deficit in overall and all-cancer mortality, likely due to the healthy worker effect. In contrast, compared with the general U.S. population, we observed elevated rates for lung cancer, ischemic heart disease, and transport-related accidents. Lung cancer rates were elevated among all drivers (SMR = 1.10; 95% CI, 1.02-1.19) and dockworkers (SMR = 1.10; 95% CI, 0.94-1.30); ischemic heart disease was also elevated among these groups of workers [drivers, SMR = 1.49 (95% CI, 1.40-1.59); dockworkers, SMR = 1.32 (95% CI, 1.15-1.52)], as well as among shop workers (SMR = 1.34; 95% CI, 1.05-1.72).

CONCLUSIONS

In this detailed assessment of specific job categories in the U.S. trucking industry, we found an excess of mortality due to lung cancer and ischemic heart disease, particularly among drivers.

Upregulation of Cyclooxygenase-2 by Motorcycle Exhaust Particulate-Induced Reactive Oxygen Species Enhances Rat Vascular Smooth Muscle Cell Proliferation

Long-term exposure to particulate air pollution has been implicated as a risk factor for cardiovascular disease and mortality. Short-term exposure has also been suggested to contribute to complications of atherosclerosis. Aberrant regulation of smooth muscle cell proliferation is thought to associate with the pathophysiology of vascular disorders such as atherosclerosis. In this study, we investigate the influence of organic extracts of motorcycle exhaust particulates (MEPE) on rat vascular smooth muscle cell (VSMC) proliferation and related regulation signaling. Exposure of VSMCs to MEPE (10-100 microg/mL) enhanced serum-induced VSMC proliferation. The expression of proliferating cell nuclear antigen (PCNA) was also enhanced in the presence of MEPE. VSMCs treated with MEPE induced the increase in the extent of cyclooxygenase (COX)-2 mRNA and protein expression and prostaglandin E 2 production, whereas the level of COX-1 protein was unchanged. Moreover, MEPE increased the production of reactive oxygen species (ROS) in VSMCs in a dose-dependent manner. MEPE could also trigger time-dependently extracellular signal-regulated kinase (ERK)1/2 phosphorylation in VSMCs, which was attenuated by antioxidants N-acetylcysteine (NAC) and pyrrolidinedithiocarbamate (PDTC). The level of translocation of nuclear factor (NF)-kappaB-p65 in the nuclei of VSMCs was also increased under MEPE exposure. The potentiating effect of MEPE on serum-induced VSMC proliferation could be abolished by COX-2 selective inhibitor NS-398, specific ERK inhibitor PD98059, and antioxidants NAC and PDTC. Taken together, these findings suggest that MEPE may contribute to the enhancement of the pathogenesis of cardiovascular diseases by augmenting proliferation of VSMCs through a ROS-regulated ERK1/2-activated COX-2 signaling pathway.

Air pollution and emergency admissions in Boston, MA

STUDY OBJECTIVE

Many studies have shown that ambient particulate air pollution (PM) is associated with increased risk of hospital admissions and deaths for cardiovascular or respiratory causes around the world. In general these have been analysed in association with PM(10) and ozone, whereas PM(2.5) is now the particle measure of greatest health and regulatory concern. And little has been published on associations of hospital admissions and PM components.

DESIGN

This study analysed hospital admissions for myocardial infarction (15 578 patients), and pneumonia (24 857 patients) in associations with fine particulate air pollution, black carbon (BC), ozone, nitrogen dioxide (NO(2)), PM not from traffic, and carbon monoxide (CO) in the greater Boston area for the years 1995-1999 using a case-crossover analysis, with control days matched on temperature.

MAIN RESULTS

A significant association was found between NO(2) (12.7% change (95% CI: 5.8, 18)), PM(2.5) (8.6% increase (95% CI: 1.2, 15.4)), and BC (8.3% increase (95% CI: 0.2, 15.8)) and the risk of emergency myocardial infarction hospitalisation; and between BC (11.7% increase (95% CI: 4.8, 17.4)), PM(2.5) (6.5% increase (95% CI: 1.1, 11.4)), and CO (5.5% increase (95% CI: 1.1, 9.5)) and the risk of pneumonia hospitalisation.

CONCLUSIONS

The pattern of associations seen for myocardial infarction and pneumonia (strongest associations with NO(2), CO, and BC) suggests that traffic exposure is primarily responsible for the association with heart attacks.

Particulate air pollution, progression, and survival after myocardial infarction

OBJECTIVE

Several studies have examined the effect of particulate pollution (PM) on survival in general populations, but less is known about susceptible groups. Moreover, previous cohort studies have been cross-sectional and subject to confounding by uncontrolled differences between cities.

DESIGN

We investigated whether PM was associated with progression of disease or reduced survival in a study of 196,000 persons from 21 U.S. cities discharged alive following an acute myocardial infarction (MI), using within-city between-year exposure to PM. We constructed city-specific cohorts of survivors of acute MI using Medicare data between 1985 and 1999, and defined three outcomes on follow-up: death, subsequent MI, and a first admission for congestive heart failure (CHF). Yearly averages of PM(10) (particulate matter with aerodynamic diameter < 10 microm) were merged to the individual annual follow-up in each city. We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors. In the second stage of the analysis, the city-specific results were combined using a meta-regression.

RESULTS

We found significant associations with a hazard ratio for the sum of the distributed lags of 1.3 [95% confidence interval (CI), 1.2-1.5] for mortality, a hazard ratio of 1.4 (95% CI, 1.2-1.7) for a hospitalization for CHF, and a hazard ratio of 1.4 (95% CI, 1.1-1.8) for a new hospitalization for MI per 10 microg/m(3) PM(10).

CONCLUSIONS

This is the first long-term study showing a significant association between particle exposure and adverse post-MI outcomes in persons who survived an MI.

Methods for bias reduction in time-series studies of particulate matter air pollution and mortality

In many cities of the United States, measurements of ambient particulate matter air pollution (PM) are available only every sixth day. Time-series studies conducted in these cities that investigate the relationship between mortality and PM are restricted to using a single day's PM as the measure of PM exposure, rather than using measurements taken over several consecutive days. Studies showed that using a single-day PM as the measure of PM exposure can result in estimates that have a negative bias, sometimes in the order of over half of the value being estimated. In this article two methods are introduced that can be used to obtain estimates that can in some situations reduce the bias to negligible proportions when only every-sixth-day PM concentrations are available. Using one of these methods, the national average PM mortality effect estimates obtained for total mortality and cardiovascular and respiratory mortality, respectively, correspond to 0.27% and 0.39% increases in mortality per 10-microg/m3 increment in PM. The corresponding effect estimates obtained using the single-day lag-1 PM concentration are 0.18% and 0.23%. The estimates obtained using the lag-1 PM concentration were the most widely reported results from the recent multicity National Morbidity, Mortality, and Air Pollution Study (NMMAPS) analyses. The more accurate estimates obtained from the methods introduced in this article will enable more accurate quantification of the increased incidence in mortality due to elevation in PM levels and the benefit of current or more stringent regulatory standards.

Short-term effects of ozone air pollution on ischaemic stroke occurrence: a case-crossover analysis from a 10-year population-based study in Dijon, France

OBJECTIVE

To evaluate the association between air pollutants and the occurrence of acute stroke from 10-year population-based study.

METHODS

The daily stroke count was obtained from Dijon Stroke Register between March 1994 and December 2004. The register recorded all first-ever strokes among residents of Dijon (150,000 inhabitants) in France, using standard diagnostic criteria. Pollutant concentrations (SO2, CO, NO2, O3 and PM10) were measured hourly. A bi-directional case-crossover design was used to examine the association between air pollutant and stroke onset. The conditional logistic regression model included the meteorological parameters (temperature, relative humidity), influenza epidemics and holidays.

RESULTS

The authors collected 493 large artery infarcts, 397 small artery infarcts, 530 cardio-embolic infarcts, 67 undeterminate infarcts, 371 transient ischaemic attacks and 220 haemorrhagic strokes. For single-pollutant model and for a 10 mg/m(3) increase of O3 exposure, a positive association was observed only in men, over 40 years of age, between ischaemic stroke occurrence and O3 levels with 1-day lag, (OR 1.133, 95% CI 1.052 to 1.220) and 0-day lag (OR 1.058, 95% CI 0.987 to 1.134). No significant associations were found for haemorrhagic stroke. In two-pollutant models, the effects of O3 remained significant after each of the other pollutants were included in the model, in particular with PM10. A significant association was observed for ischaemic strokes of large arteries (p = 0.02) and for transient ischaemic attacks (p = 0.01). Moreover, the authors found an exposure-response relations between O3 exposure and ischaemic stroke (test for trend, p = 0.01). An increase in association in men with several cardiovascular risk factors (smoker, dyslipidemia and hypertension) was also observed.

CONCLUSION

These observational data argue for an association between ischaemic stroke occurrence and O3 pollution levels; these results still need to be confirmed by other studies.

Field performance of a nephelometer in rural kitchens: effects of high humidity excursions and correlations to gravimetric analyses

Rural kitchens of solid-fuel burning households constitute the microenvironment responsible for the majority of human exposures to health-damaging air pollutants, particularly respirable particles and carbon monoxide. Portable nephelometers facilitate cheaper, more precise, time-resolved characterization of particles in rural homes than are attainable by gravitational methods alone. However, field performance of nephelometers must contend with aerosols that are highly variable in terms of chemical content, size, and relative humidity. Previous field validations of nephelometer performance in residential settings explore relatively low particle concentrations, with the vast majority of 24-h average gravitational PM2.5 concentrations falling below 40 microg/m3. We investigate relationships between 24-h gravitational particle measurements and nephelometric data logged by the personal DataRAM (pDR) in highly polluted rural Chinese kitchens, where gravitationally determined 24-h average respirable particle concentrations were as high as 700 microg/m3. We find that where relative humidity remained below 95%, nephelometric response was strongly linear despite complex mixtures of aerosols and variable ambient conditions. Where 95% relative humidity was exceeded for even a brief duration, nephelometrically determined 24-h mean particle concentrations were nonsystematically distorted relative to gravitational data, and neither concurrent relative humidity measurements nor use of robust statistical measures of central tendency offered means of correction. This nonsystematic distortion is particularly problematic for rural exposure assessment studies, which emphasize upper quantiles of time-resolved particle measurements within 24-h samples. Precise, accurate interpretation of nephelometrically resolved short-term particle concentrations requires calibration based on short-term gravitational sampling.

Determinants of personal and indoor PM2.5 and absorbance among elderly subjects with coronary heart disease

Epidemiological studies have established an association between outdoor levels of fine particles (PM2.5) and cardiovascular health. However, there is little information on the determinants of PM2.5 exposures among persons with cardiovascular disease, a potentially susceptible population group. Daily outdoor, indoor and personal PM2.5 and absorbance (proxy for elemental carbon) concentrations were measured among elderly subjects with cardiovascular disease in Amsterdam, the Netherlands, and Helsinki, Finland, during the winter and spring of 1998-1999 within the framework of the ULTRA study. There were 37 non-smoking subjects in Amsterdam and 47 in Helsinki. In Amsterdam, where there were enough exposure events for analyses, exposure to environmental tobacco smoke (ETS) indoors was a major source of between-subject variation in PM2.5 exposures, and a strong determinant of PM2.5 and absorbance exposures. When the days with ETS were excluded, within-subject variation accounted for 89% of the total variation in personal PM2.5 and 97% in absorbance in Amsterdam. The respective figures were 66% and 61% in Helsinki. In both cities, outdoor levels of PM2.5 and absorbance were major determinants of personal and indoor levels. Traffic was also an important determinant of absorbance: living near a major street increased exposure by 22%, and every hour spent in a motor vehicle by 13% in Amsterdam. The respective increases were 37% and 9% in Helsinki. Cooking was associated with increased levels of both absorbance and PM2.5. Our results demonstrate that by using questionnaires in connection with outdoor measurements, exposure estimation of PM2.5 and its combustion originating fraction can be improved among elderly persons with compromised health.

Evaluation of health benefits for improving indoor air quality in workplace

In contrast to a majority of reported damage-cost literature being focused on outdoor pollution, this paper describes the development of a protocol that links population exposure data with reported epidemiological concentration-response coefficients. A change in indoor particulate level is expressed as a change in total exposure levels, which is then linked with a corresponding change in ambient particulate concentrations before evaluating the associated health benefits. In this study, the development of protocol is illustrated by using a typical office building environment and daily time activity patterns of office occupants in Hong Kong. Our results indicate that some benefit gains for the owners-employers and the society would be anticipated if certain filter set configurations had been adopted. However, the amount of benefit gains for the owners-employers is shown to be increased with the average salary level of employees and the duration of their stay in offices.

E-Selectin expression in human endothelial cells exposed to PM10: the role of endotoxin and insoluble fraction

Exposure to PM10 is associated with cardiovascular effects. We evaluated the effects of PM10 on E-Selectin expression and monocytic cell adhesion in human umbilical vein endothelial cells (HUVECs). HUVEC were exposed to PM10 (5-40 microg/cm2) for 6 h, following which surface E-Selectin expression was detected by fluorescence microscopy and flow cytometry. The effects of total particles, particles treated with polymixin-B to block the effects of endotoxin, and both soluble and insoluble fractions of particles, were assessed. Incubation with PM10 lead to a concentration-related increase of E-Selectin expression (>seven-fold increase at 40 microg/cm2). Particles pre-treated with polymixin-B inhibited E-Selectin expression to a level slightly higher than untreated particles. An increase in fluorescence was also observed with the insoluble fraction, while the soluble fraction had no significant effect. HUVEC exposed to PM10 were also evaluated for adhesivity of monocytic cells (U937). PM10 strongly increased the adhesion of U937 cells to HUVEC. In conclusion, PM10 induces endothelial cell activation, evidenced by enhanced E-Selectin expression. This activation is manifested functionally as an increase in monocytic cell adhesion. Insoluble components as well as endotoxins appear to be responsible for this activity.

A community study of the effect of particulate matter on blood measures of inflammation and thrombosis in an elderly population

BACKGROUND

The mechanism behind the triggering effect of fine particulate matter (PM) air pollution on cardiovascular events remains elusive. We postulated that elevated levels of PM would be associated with increased blood levels of inflammatory and thrombotic markers in elderly individuals. We also hypothesized that elevated PM would increase levels of cytokines in individuals with heart disease.

METHODS

We measured these blood markers in 47 elderly individuals with (23) and without (16 COPD and 8 healthy) cardiovascular disease (CVD) on 2 or 3 mornings over a 5 or 10-day period between February 2000 and March 2002. Blood measures were paired with residence level outdoor PM measured by nephelometry. Analyses determined the within-individual effect of 24-hour averaged outdoor PM on blood measures.

RESULTS

Analyses found no statistically significant effect of a same day 10 ug/m3 increase in fine PM on log transformed levels of CRP 1.21 fold-rise [95% CI: 0.86, 1.70], fibrinogen 1.02 fold-rise [95% CI: 0.98, 1.06], or D-dimer 1.02 fold-rise [95% CI: 0.88, 1.17] in individuals with CVD. One-day lagged analyses in the CVD subgroup found similar null results. These same models found no change in these blood markers at the same-day or 1-day lag in the group without CVD. In 21 individuals with CVD, a 10 mug/m3 increase in same-day PM was associated with a 1.3 fold-rise [95% CI: 1.1, 1.7] in the level of monocyte chemoattractant protein-1.

CONCLUSION

We did not find consistent effects of low ambient levels of PM on blood measures of inflammation or thrombosis in elderly individuals.

Health effects associated with exposure to ambient air pollution

The World Health Organization has identified ambient air pollution as a high public health priority, based on estimates of air pollution related death and disability-adjusted life years derived in its Global Burden of Disease initiative. The NERAM Colloquium Series on Health and Air Quality was initiated to strengthen the linkage between scientists, policymakers, and other stakeholders by reviewing the current state of science, identifying policy-relevant gaps and uncertainties in the scientific evidence, and proposing a path forward for research and policy to improve air quality and public health. The objective of this paper is to review the current state of science addressing the impacts of air pollution on human health. The paper is one of four background papers prepared for the 2003 NERAM/AirNet Conference on Strategies for Clean Air and Health, the third meeting in the international Colloquium Series. The review is based on the framework and findings of the U.S. National Research Committee (NRC) on Research Priorities for Airborne Particulate Matter and addresses key questions underlying air quality risk management policy decisions.