Particulate matter and daily mortality and hospital admissions in the west midlands conurbation of the United Kingdom: associations with fine and coarse particles, black smoke and sulphate

Synoptic weather typing applied to air pollution mortality among the elderly in 10 Canadian cities

BACKGROUND

Synoptic circulation patterns (large-scale weather systems) affect ambient levels of air pollution, as well as the relationship between air pollution and human health.

OBJECTIVE

To investigate the air pollution-mortality relationship within weather types and seasons, and to determine which combination of atmospheric conditions may pose increased health threats in the elderly age categories.

METHODS

The relative risk of mortality (RR) due to air pollution was examined using Poisson generalized linear models (GLMs) within specific weather types. Analysis was completed by weather type and age group (all ages, ≤64, 65-74, 75-84, ≥85 years) in ten Canadian cities from 1981 to 1999.

RESULTS

There was significant modification of RR by weather type and age. When examining the entire population, weather type was shown to have the greatest modifying effect on the risk of dying due to ozone (O3). This effect was highest on average for the dry tropical (DT) weather type, with the all-age RR of mortality at a population weighted mean (PWM) found to be 1.055 (95% CI 1.026-1.085). All-weather type risk estimates increased with age due to exposure to carbon monoxide (CO), nitrogen dioxide (NO2), and sulphur dioxide (SO2). On average, RR increased by 2.6, 3.8 and 1.5% for the respective pollutants between the ≤64 and ≥85 age categories. Conversely, mean ozone estimates remained relatively consistent with age. Elevated levels of air pollution were found to be detrimental to the health of elderly individuals for all weather types. However, the entire population was negatively effected by air pollution on the hot dry (DT) and hot humid (MT) days.

CONCLUSIONS

We identified a significant modification of RR for mortality due to air pollution by age, which is enhanced under specific weather types. Efforts should be targeted at minimizing pollutant exposure to the elderly and/or all age groups with respect to weather type in question.

The acute effects of fine particles on respiratory mortality and morbidity in Beijing, 2004-2009

Recent epidemiological and toxicological studies have shown associations between particulate matter and human health. However, the estimates of adverse health effects are inconsistent across many countries and areas. The stratification and interaction models were employed within the context of the generalized additive Poisson regression equation to examine the acute effects of fine particles on respiratory health and to explore the possible joint modification of temperature, humidity, and season in Beijing, China, for the period 2004-2009. The results revealed that the respiratory health damage threshold of the PM2.5 concentration was mainly within the range of 20-60 μg/m(3), and the adverse effect of excessively high PM2.5 concentration maintained a stable level. In the most serious case, an increase of 10 μg/m(3) PM2.5 results in an elevation of 4.60 % (95 % CI 3.84-4.60 %) and 4.48 % (95 % CI 3.53-5.41 %) with a lag of 3 days, values far higher than the average level of 0.69 % (95 % CI 0.54-0.85 %) and 1.32 % (95 % CI 1.02-1.61 %) for respiratory mortality and morbidity, respectively. There were strong seasonal patterns of adverse effects with the seasonal variation of temperature and humidity. The growth rates of respiratory mortality and morbidity were highest in winter. And, they increased 1.4 and 1.8 times in winter, greater than in the full year as PM2.5 increased 10 μg/m(3).

Short-term associations between fine and coarse particulate matter and hospitalizations in Southern Europe: results from the MED-PARTICLES project

BACKGROUND

Evidence on the short-term effects of fine and coarse particles on morbidity in Europe is scarce and inconsistent.

OBJECTIVES

We aimed to estimate the association between daily concentrations of fine and coarse particles with hospitalizations for cardiovascular and respiratory conditions in eight Southern European cities, within the MED-PARTICLES project.

METHODS

City-specific Poisson models were fitted to estimate associations of daily concentrations of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), ≤ 10 μm (PM10), and their difference (PM2.5-10) with daily counts of emergency hospitalizations for cardiovascular and respiratory diseases. We derived pooled estimates from random-effects meta-analysis and evaluated the robustness of results to co-pollutant exposure adjustment and model specification. Pooled concentration-response curves were estimated using a meta-smoothing approach.

RESULTS

We found significant associations between all PM fractions and cardiovascular admissions. Increases of 10 μg/m3 in PM2.5, 6.3 μg/m3 in PM2.5-10, and 14.4 μg/m3 in PM10 (lag 0-1 days) were associated with increases in cardiovascular admissions of 0.51% (95% CI: 0.12, 0.90%), 0.46% (95% CI: 0.10, 0.82%), and 0.53% (95% CI: 0.06, 1.00%), respectively. Stronger associations were estimated for respiratory hospitalizations, ranging from 1.15% (95% CI: 0.21, 2.11%) for PM10 to 1.36% (95% CI: 0.23, 2.49) for PM2.5 (lag 0-5 days).

CONCLUSIONS

PM2.5 and PM2.5-10 were positively associated with cardiovascular and respiratory admissions in eight Mediterranean cities. Information on the short-term effects of different PM fractions on morbidity in Southern Europe will be useful to inform European policies on air quality standards.

Measurement of personal and integrated exposure to particulate matter and co-pollutant gases: a panel study

Personal exposure measurement can serve as an effective tool to understand the effect of exposure to air pollutants. Alternatively, exposure assessment using pollutant concentrations in different microenvironments and accurate time-activity information for the subjects can provide good information regarding human integrated exposure. A panel of 18 healthy students of Indian Institute of Technology (IIT) Kanpur in the age group of 18 to 30 years participated in the personal exposure measurements for particulate matter, CO, NO(2) and VOC during post-monsoon and pre-monsoon seasons. Overall, 432 h person exposure data was collected in this study. The major sources of particulate and gaseous co-pollutants were identified. These directly obtained personal exposure values were then compared to the indirectly estimated integrated exposure values. Personal and integrated exposures gave statistically similar results. Through this study, we have shown that integrated exposure values could closely estimate the personal exposure values for particulate matter that can significantly reduce time and cost involved in personal exposure studies. The lung parameters for all the subjects measured during the pre-monsoon and post-monsoon seasons showed statistically significant reduction during pre-monsoon. This was attributed to the high levels of coarse particles during pre-monsoon.

Using a photochemical model to assess the horizontal, vertical and time distribution of PM(2.5) in a complex area: relationships between the regional and local sources and the meteorological conditions

A photochemical transport model has been implemented to assess the PM(2.5) spatial and temporal distribution in Venice-Mestre. This is a large city of the eastern Po Valley, which is recognized having among the highest levels of many air pollutants in Europe. This study is a first attempt to evaluate PM(2.5) distribution in such a complex ecosystem strongly affected by several different environments (the adjacent Alps, the lagoon and the sea) that create a spatial discontinuity of climate. Model performance was tested with experimental results. Samples have been collected in three sites representative of different emission characteristics. A second simulation was performed with clean boundary conditions to check the influence of the background concentrations on the study domain. Local and regional contributions were found to be strongly dependent on seasonal conditions and on local meteorology. A further analysis was conducted to predict the PM(2.5) distribution with respect to air mass movements. The non-homogeneity of surfaces affects the Planetary Boundary Layer (PBL) behavior. This consequently influences the vertical distribution of PM(2.5) especially during cold seasons and on occasion of particular meteorological events.

Regular exercise training attenuates pulmonary inflammatory responses to inhaled alumina refinery dust in mice

Exposure to alumina dust has been recently associated with impaired lung mechanics and inflammation. We aimed at evaluating if moderate exercise training prevents these outcomes. Twenty-three female BALB/c mice (25-30g) were randomly divided in two main groups: control (C) and exercise (E), which were submitted, or not, to 15min of swimming, 5 days/week during 4 weeks. Then, the animals were exposed for 1h to either saline solution (CS or ES) or to a suspension of 8mg/m(3) of alumina dust (CA or EA). Twenty-four hours later pulmonary mechanics was determined by the end-inflation occlusion method. Left lungs were prepared for histology and right lungs for TGF-β determination. Static elastance increased after alumina dust exposure independently of swimming. In CA group the viscoelastic component of elastance, the viscoelastic/inhomogeneous pressure, the polymorphonuclear amount, the fraction area of alveolar collapse and TGF-β increased. Thus, exercise training may mitigate the pro-inflammatory response to inhaled aluminum refinery dust.

Association between ambient particulate matter and daily cause-specific mortality in Tanggu, Tianjin Binhai New Area, China

The aim of the study was to determine whether the area of Tanggu, Tianjin Binhai New Economic Developing Area, China, is subject to similar effects of ambient particulate matter less than 10 micrometres in aerodynamic diameter (PM10) similar to other areas of China. This study was designed to investigate cause-specific mortality risks associated with air pollution in this geographical region. The present study used a time-series analysis to explore the relationship between PM10 and the cause-specific mortalities for non-accidental, cardiovascular, and cardiopulmonary mortality from 1 January 2006 to 31 December 2010. A 10 μg/m(3) increment of PM10 was associated with a 1.02% (95% confidence interval (CI): 0.48, 1.56) increase in cardiovascular mortality, and a 0.88% (95% CI: 0.36, 1.39) increase in cardiopulmonary mortality. In addition, the effects from PM10 appear to be consistent with multi-pollutant models. The results show that there are strong associations between daily cardiovascular and cardiopulmonary mortality and ambient PM10 exposure.

A meta-analysis and multisite time-series analysis of the differential toxicity of major fine particulate matter constituents

Health risk assessments of particulate matter less than 2.5 μm in diameter (PM(2.5)) often assume that all constituents of PM(2.5) are equally toxic. While investigators in previous epidemiologic studies have evaluated health risks from various PM(2.5) constituents, few have conducted the analyses needed to directly inform risk assessments. In this study, the authors performed a literature review and conducted a multisite time-series analysis of hospital admissions and exposure to PM(2.5) constituents (elemental carbon, organic carbon matter, sulfate, and nitrate) in a population of 12 million US Medicare enrollees for the period 2000-2008. The literature review illustrated a general lack of multiconstituent models or insight about probabilities of differential impacts per unit of concentration change. Consistent with previous results, the multisite time-series analysis found statistically significant associations between short-term changes in elemental carbon and cardiovascular hospital admissions. Posterior probabilities from multiconstituent models provided evidence that some individual constituents were more toxic than others, and posterior parameter estimates coupled with correlations among these estimates provided necessary information for risk assessment. Ratios of constituent toxicities, commonly used in risk assessment to describe differential toxicity, were extremely uncertain for all comparisons. These analyses emphasize the subtlety of the statistical techniques and epidemiologic studies necessary to inform risk assessments of particle constituents.

Association between unemployment, income, education level, population size and air pollution in Czech cities: evidence for environmental inequality? A pilot national scale analysis

We analyzed differentials in exposure to SO(2), PM(10) and NO(2) among Czech urban populations categorized according to education level, unemployment rate, population size and average annual salary. Altogether 39 cities were included in the analysis. The principal component analysis revealed two factors explaining 72.8% of the data variability. The first factor explaining 44.7% of the data variability included SO(2), PM(10), low education level and high unemployment, documenting that inhabitants with unfavorable socioeconomic status mainly reside in smaller cities with higher concentration levels of combustion-related air pollutants. The second factor explaining 28.1% of the data variability included NO(2), high salary, high education level and large population, suggesting that large cities with residents with higher socioeconomic status are exposed to higher levels of traffic-related air pollution. We conclude that, after more than a decade of free-market economy, the Czech Republic, a former Soviet satellite with a centrally planned economy, displays signs of a certain kind of environmental inequality, since environmental hazards are unevenly distributed among the Czech urban populations.

Ambient air pollution and the risk of acute ischemic stroke

BACKGROUND

The link between daily changes in level of ambient fine particulate matter (PM) air pollution (PM <2.5 μm in diameter [PM(2.5)]) and cardiovascular morbidity and mortality is well established. Whether PM(2.5) levels below current US National Ambient Air Quality Standards also increase the risk of ischemic stroke remains uncertain.

METHODS

We reviewed the medical records of 1705 Boston area patients hospitalized with neurologist-confirmed ischemic stroke and abstracted data on the time of symptom onset and clinical characteristics. The PM(2.5) concentrations were measured at a central monitoring station. We used the time-stratified case-crossover study design to assess the association between the risk of ischemic stroke onset and PM(2.5) levels in the hours and days preceding each event. We examined whether the association with PM(2.5) levels differed by presumed ischemic stroke pathophysiologic mechanism and patient characteristics.

RESULTS

The estimated odds ratio (OR) of ischemic stroke onset was 1.34 (95% CI, 1.13-1.58) (P < .001) following a 24-hour period classified as moderate (PM(2.5) 15-40 μg/m(3)) by the US Environmental Protection Agency's (EPA) Air Quality Index compared with a 24-hour period classified as good (≤15 μg/m(3)). Considering PM(2.5) levels as a continuous variable, we found the estimated odds ratio of ischemic stroke onset to be 1.11 (95% CI, 1.03-1.20) (P = .006) per interquartile range increase in PM(2.5) levels (6.4 μg/m(3)). The increase in risk was greatest within 12 to 14 hours of exposure to PM(2.5) and was most strongly associated with markers of traffic-related pollution.

CONCLUSION

These results suggest that exposure to PM(2.5) levels considered generally safe by the US EPA increase the risk of ischemic stroke onset within hours of exposure.

Effects of coarse particulate matter on emergency hospital admissions for respiratory diseases: a time-series analysis in Hong Kong

BACKGROUND

Many epidemiological studies have linked daily counts of hospital admissions to particulate matter (PM) with an aerodynamic diameter ≤ 10 μm (PM10) and ≤ 2.5 μm (PM2.5), but relatively few have investigated the relationship of hospital admissions with coarse PM (PMc; 2.5-10 μm aerodynamic diameter).

OBJECTIVES

We conducted this study to estimate the health effects of PMc on emergency hospital admissions for respiratory diseases in Hong Kong after controlling for PM2.5 and gaseous pollutants.

METHODS

We conducted a time-series analysis of associations between daily emergency hospital admissions for respiratory diseases in Hong Kong from January 2000 to December 2005 and daily PM2.5 and PMc concentrations. We estimated PMc concentrations by subtracting PM2.5 from PM10 measurements. We used generalized additive models to examine the relationship between PMc (single- and multiday lagged exposures) and hospital admissions adjusted for time trends, weather conditions, influenza outbreaks, PM2.5, and gaseous pollutants (nitrogen dioxide, sulfur dioxide, and ozone).

RESULTS

A 10.9-μg/m(3) (interquartile range) increase in the 4-day moving average concentration of PMc was associated with a 1.94% (95% confidence interval: 1.24%, 2.64%) increase in emergency hospital admissions for respiratory diseases that was attenuated but still significant after controlling for PM2.5. Adjusting for gaseous pollutants and altering models assumptions had little influence on PMc effect estimates.

CONCLUSION

PMc was associated with emergency hospital admissions for respiratory diseases in Hong Kong independent of PM2.5 and gaseous pollutants. Further research is needed to evaluate health effects of different components of PMc.

Sources of high PM2.5 concentrations in Milan, Northern Italy: molecular marker data and CMB modelling

In Milan (MI), the largest city in Northern Italy, the annually average PM2.5 concentration is above 25 μg m(-3), the value that the EU established as a target for 2010, and the upper limit from 2015 onwards (2008/30/CE). Over a three-year period (2006-2009) PM concentrations and chemical compositions were measured in an urban site (MI), a rural site (OB) and a remote site (ASC) in Northern Italy. Chemical characterization (EC/OC, inorganic ions, elements, C20-C32 n-alkanes, C2-C5 mono and dicarboxylic acids, levoglucosan and PAHs) was carried out on PM2.5 samples from the three sites, and PM10 from MI. Molecular markers were used in Chemical Mass Balance (CMB) modelling to estimate the contributions of primary sources to OC, and then PM mass from each source was reconstructed in MI, OB and ASC for different seasons. Estimates of the traffic (TR) source contribution to PM2.5 mass ranged from 4.1 (± 2.0) μg m(-3) during the summer, to 13.3 (± 6.7) μg m(-3) during the winter in MI. TR was the main primary source for PM2.5 concentrations in MI (17-24%). Its contribution was lower at the OB site (7-9%) and at the remote ASC site (3-4%). TR is a local source, while biomass burning (BB) is a diffuse regional source in Northern Italy: during fall and winter, BB was 25-30% and 27-31% of PM2.5 at MI and OB respectively. Other primary sources accounted for a small amount of the PM2.5, i.e. natural gas combustion (0-1%), plant debris (0-4%), road dust (RD=0-4%; but 15% at ASC during winter and 10% of PM10 at MI during summer) and sea salt (0-1%). Secondary inorganic+organic aerosol constituted the major part of the PM2.5 mass during spring and summer (50-65%) at the three sites.

Black carbon as an additional indicator of the adverse health effects of airborne particles compared with PM10 and PM2.5

BACKGROUND

Current air quality standards for particulate matter (PM) use the PM mass concentration [PM with aerodynamic diameters ≤ 10 μm (PM(10)) or ≤ 2.5 μm (PM(2.5))] as a metric. It has been suggested that particles from combustion sources are more relevant to human health than are particles from other sources, but the impact of policies directed at reducing PM from combustion processes is usually relatively small when effects are estimated for a reduction in the total mass concentration.

OBJECTIVES

We evaluated the value of black carbon particles (BCP) as an additional indicator in air quality management.

METHODS

We performed a systematic review and meta-analysis of health effects of BCP compared with PM mass based on data from time-series studies and cohort studies that measured both exposures. We compared the potential health benefits of a hypothetical traffic abatement measure, using near-roadway concentration increments of BCP and PM(2.5) based on data from prior studies.

RESULTS

Estimated health effects of a 1-μg/m3 increase in exposure were greater for BCP than for PM(10) or PM(2.5), but estimated effects of an interquartile range increase were similar. Two-pollutant models in time-series studies suggested that the effect of BCP was more robust than the effect of PM mass. The estimated increase in life expectancy associated with a hypothetical traffic abatement measure was four to nine times higher when expressed in BCP compared with an equivalent change in PM(2.5) mass.

CONCLUSION

BCP is a valuable additional air quality indicator to evaluate the health risks of air quality dominated by primary combustion particles.

The lag structure and the general effect of ozone exposure on pediatric respiratory morbidity

Up to now no study has investigated the lag structure of children's respiratory morbidity due to surface ozone. In the present study, we investigate the lag structure and the general effect of surface ozone exposure on children and adolescents' respiratory morbidity using data from a particularly well suited area in southern Europe to assess the health effects of surface ozone. The effects of surface ozone are estimated using the recently developed distributed lag non-linear models, allowing for a relatively long timescale, while controlling for weather effects, a range of other air pollutants, and long and short term patterns. The public health significance of the estimated effects is higher than has been previously reported in the literature, providing evidence contrary to the conjecture that the surface ozone-morbidity association is mainly due to short-term harvesting. In fact, our data analysis reveals that the effects of surface ozone at medium and long timescales (harvesting-resistant) are substantially larger than the effects at shorter timescales (harvesting-prone), a finding that is consistent with all children and adolescents being affected by high surface ozone concentrations, and not just the very frail.

Fine particulate air pollution (PM2.5) and the risk of acute ischemic stroke

BACKGROUND

Short-term changes in levels of fine ambient particulate matter (PM2.5) may increase the risk of acute ischemic stroke; however, results from prior studies have been inconsistent. We examined this hypothesis using data from a multicenter prospective stroke registry.

METHODS

We analyzed data from 9202 patients hospitalized with acute ischemic stroke, having a documented date and time of stroke onset, and residing within 50 km of a PM2.5 monitor in 8 cities in Ontario, Canada. We evaluated the risk of ischemic stroke onset associated with PM2.5 in each city using a time-stratified case-crossover design, matching on day of week and time of day. We then combined these city-specific estimates using random-effects meta-analysis techniques. We examined whether the effects of PM2.5 differed across strata defined by patient characteristics and ischemic stroke etiology.

RESULTS

Overall, PM2.5 was associated with a -0.7% change in ischemic stroke risk per 10-μg/m increase in PM2.5 (95% confidence interval = -6.3% to 5.1%). These overall negative results were robust to a number of sensitivity analyses. Among patients with diabetes mellitus, PM2.5 was associated with an 11% increase in ischemic stroke risk (1% to 22%). The association between PM2.5 and ischemic stroke risk varied according to stroke etiology, with the strongest associations observed for strokes due to large-artery atherosclerosis and small-vessel occlusion.

CONCLUSIONS

These results do not support the hypothesis that short-term increases in PM2.5 levels are associated with ischemic stroke risk overall. However, specific patient subgroups may be at increased risk of particulate-related ischemic strokes.

Meta-analysis of the Association between Short-Term Exposure to Ambient Ozone and Respiratory Hospital Admissions

Ozone is associated with health impacts including respiratory outcomes; however, results differ across studies. Meta-analysis is an increasingly important approach to synthesizing evidence across studies. We conducted meta-analysis of short-term ozone exposure and respiratory hospitalizations to evaluate variation across studies and explore some of the challenges in meta-analysis. We identified 136 estimates from 96 studies and investigated how estimates differed by age, ozone metric, season, lag, region, disease category, and hospitalization type. Overall results indicate associations between ozone and various types of respiratory hospitalizations; however, study characteristics affected risk estimates. Estimates were similar, but higher, for the elderly compared to all ages and for previous day exposure compared to same day exposure. Comparison across studies was hindered by variation in definitions of disease categories, as some (e.g., asthma) were identified through ≥3 different sets of ICD codes. Although not all analyses exhibited evidence of publication bias, adjustment for publication bias generally lowered overall estimates. Emergency hospitalizations for total respiratory disease increased 4.47% (95% interval 2.48, 6.50%) per 10ppb 24-hr ozone among the elderly without adjustment for publication bias and 2.97% (1.05, 4.94%) with adjustment. Comparison of multi-city study results and meta-analysis based on single-city studies further suggested publication bias.

Time-series analysis of mortality effects of fine particulate matter components in Detroit and Seattle

BACKGROUND

Recent toxicological and epidemiological studies have shown associations between particulate matter (PM) and adverse health effects, but which PM components are most influential is less well known.

OBJECTIVES

In this study, we used time-series analyses to determine the associations between daily fine PM [PM ≤ 2.5 µm in aerodynamic diameter (PM2.5)] concentrations and daily mortality in two U.S. cities-Seattle, Washington, and Detroit, Michigan.

METHODS

We obtained daily PM2.5 filters for the years of 2002-2004 and analyzed trace elements using X-ray fluorescence and black carbon using light reflectance as a surrogate measure of elemental carbon. We used Poisson regression and distributed lag models to estimate excess deaths for all causes and for cardiovascular and respiratory diseases adjusting for time-varying covariates. We computed the excess risks for interquartile range increases of each pollutant at lags of 0 through 3 days for both warm and cold seasons.

RESULTS

The cardiovascular and respiratory mortality series exhibited different source and seasonal patterns in each city. The PM2.5 components and gaseous pollutants associated with mortality in Detroit were most associated with warm season secondary aerosols and traffic markers. In Seattle, the component species most closely associated with mortality included those for cold season traffic and other combustion sources, such as residual oil and wood burning.

CONCLUSIONS

The effects of PM2.5 on daily mortality vary with source, season, and locale, consistent with the hypothesis that PM composition has an appreciable influence on the health effects attributable to PM.

Environmentally persistent free radicals induce airway hyperresponsiveness in neonatal rat lungs

Background

Increased asthma risk/exacerbation in children and infants is associated with exposure to elevated levels of ultrafine particulate matter (PM). The presence of a newly realized class of pollutants, environmentally persistent free radicals (EPFRs), in PM from combustion sources suggests a potentially unrecognized risk factor for the development and/or exacerbation of asthma.

Methods

Neonatal rats (7-days of age) were exposed to EPFR-containing combustion generated ultrafine particles (CGUFP), non-EPFR containing CGUFP, or air for 20 minutes per day for one week. Pulmonary function was assessed in exposed rats and age matched controls. Lavage fluid was isolated and assayed for cellularity and cytokines and in vivo indicators of oxidative stress. Pulmonary histopathology and characterization of differential protein expression in lung homogenates was also performed.

Results

Neonates exposed to EPFR-containing CGUFP developed significant pulmonary inflammation, and airway hyperreactivity. This correlated with increased levels of oxidative stress in the lungs. Using differential two-dimensional electrophoresis, we identified 16 differentially expressed proteins between control and CGUFP exposed groups. In the rats exposed to EPFR-containing CGUFP; peroxiredoxin-6, cofilin1, and annexin A8 were upregulated.

Conclusions

Exposure of neonates to EPFR-containing CGUFP induced pulmonary oxidative stress and lung dysfunction. This correlated with alterations in the expression of various proteins associated with the response to oxidative stress and the regulation of glucocorticoid receptor translocation in T lymphocytes.

Including viral infection data supports an association between particulate pollution and respiratory admissions

OBJECTIVE

To refine and revise previous air pollution, climate and health time series analysis in Christchurch, New Zealand, introducing viral identification data (positive identification count and outbreak, defined as two of more positive tests).

METHOD

The effects on daily respiratory admissions for five years (1998-2002) of air pollution (PM(10) ), climate and virology (incorporating actual counts and outbreaks of influenza A and B (INF), para influenza virus type 3 (PIV) and respiratory syncytial virus (RSV) were examined using generalised additive models (GAMs), which are one of semiparametric models. Results were also compared with a model that included climate and air pollution parameters but without the inclusion of virology data. The data were analysed aggregately and then stratified by age group and season.

RESULTS

Different virology data detected various association levels. The highest estimates were a 3.93% (CI: 2.69-5.17) and a 3.88% (CI: 2.65-5.12) rise in respiratory admissions for a rise of 10 µg/m(3) annual PM(10) with outbreak and actual counts of PIV respectively for 0-19 years old with a three-day lag.

CONCLUSION

Refining a statistical model with the addition of virology data gives a similar estimation of the association between PM(10) levels and respiratory admissions to previous research. Use of the indicator of an outbreak of viral infection appears to be similar to actual count of viruses detected.

Impact of fine and ultrafine particles on emergency hospital admissions for cardiac and respiratory diseases

BACKGROUND

Little is known about the short-term effects of ultrafine particles.

METHODS

We evaluated the effect of particulate matter with an aerodynamic diameter <or=10 microm (PM10), <or=2.5 microm (PM2.5), and ultrafine particles on emergency hospital admissions in Rome 2001-2005. We studied residents aged >or=35 years hospitalized for acute coronary syndrome, heart failure, lower respiratory tract infections, and chronic obstructive pulmonary disease (COPD). Information was available for factors indicating vulnerability, such as age and previous admissions for COPD. Particulate matter data were collected daily at one central fixed monitor. A case-crossover analysis was performed using a time-stratified approach. We estimated percent increases in risk per 14 microg/m PM10, per 10 microg/m PM2.5, and per 9392 particles/mL.

RESULTS

An immediate impact (lag 0) of PM2.5 on hospitalizations for acute coronary syndrome (2.3% [95% confidence interval = 0.5% to 4.2%]) and heart failure (2.4% [0.3% to 4.5%]) was found, whereas the effect on lower respiratory tract infections (2.8% [0.5% to 5.2%]) was delayed (lag 2). Particle number concentration showed an association only with admissions for heart failure (lag 0-5; 2.4% [0.2% to 4.7%]) and COPD (lag 0; 1.6% [0.0% to 3.2%]). The effects were generally stronger in the elderly and during winter. There was no clear effect modification with previous COPD.

CONCLUSIONS

We found sizeable acute health effects of fine and ultrafine particles. Although differential reliability in exposure assessment, in particular of ultrafine particles, precludes a firm conclusion, the study indicates that particulate matter of different sizes tends to have diverse outcomes, with dissimilar latency between exposure and health response.

Residential Proximity to Freeways is Associated with Uncontrolled Asthma in Inner-City Hispanic Children and Adolescents

Background. Proximity to heavy traffic has been linked to increased asthma severity. However, it is unknown whether exposure to heavy traffic is associated with the ability to maintain asthma control. Objectives. This study examines whether exposure to heavy traffic is associated with the ability to maintain asthma control in inner-city children. Methods. 756 inner-city asthmatic Hispanic children were followed for one year in a pediatric asthma management program (Breathmobile). At each scheduled visit, asthma specialist tracked patients' asthma severity and managed their asthma based on the NAEPP guidelines. The patients' residential distance from the nearest freeway was calculated based on residential address at study entry. Distance to nearest freeway was used as a surrogate marker for high exposure from traffic-related air pollutants. Results. Patients who lived near a freeway were significantly more likely to have asthma that was not well controlled (P = .03). Patients with intermittent and mild baseline severity have a two-fold increased risk of having asthma that is uncontrolled if they lived <2 miles from a freeway (OR = 2.2, P = .04). Conclusion. In children with asthma, residential proximity to freeways is associated with uncontrolled asthma.

Roles of oxidative stress in signaling and inflammation induced by particulate matter

This review reports the role of oxidative stress in impairing the function of lung exposed to particulate matter (PM). PM constitutes a heterogeneous mixture of various types of particles, many of which are likely to be involved in oxidative stress induction and respiratory diseases. Probably, the ability of PM to cause oxidative stress underlies the association between increased exposure to PM and exacerbations of lung disease. Mostly because of their large surface area, ultrafine particles have been shown to cause oxidative stress and proinflammatory effects in different in vivo and in vitro studies. Particle components and surface area may act synergistically inducing lung inflammation. In this vein, reactive oxygen species elicited upon PM exposure have been shown to activate a number of redox-responsive signaling pathways and Ca(2+) influx in lung target cells that are involved in the expression of genes that modulate relevant responses to lung inflammation and disease.

Seasonal variations in chemical composition and in vitro biological effects of fine PM from Milan

Fine particulate matter (PM1 and PM2.5) was collected in Milan over the summer (August-September) and winter (January-March) seasons of 2007/2008. Particles were analyzed for their chemical composition (inorganic ions, elements and PAHs) and the effects produced on the human lung carcinoma epithelial cell line A549. In vitro tests were performed to assess cell viability with MTT assay, cytokine release (IL-6 and IL-8) with ELISA, and DNA damage with COMET assay. Results were investigated by bivariate analysis and multivariate data analysis (Principal Component Analysis, PCA) to investigate the relationship between PM chemical composition and the biological effects produced by cell exposure to 12 microg cm(-2). The different seasonal chemical composition of PM showed to influence some biological properties. Summer PM samples had a high mass contribution of SO(4)(=) (13+/-2%) and were enriched in some elements, like Al, As, Cr, Cu, and Zn, compared to winter PM samples. Cell viability reduction was two times higher for summer PM samples in comparison with winter ones (27+/-5% and 14+/-5%, respectively), and the highest correlation coefficients between cell viability reduction and single chemical components were with As (R(2)=0.57) and SO(4)(=) (R(2)=0.47). PM1 affected cell viability reduction and induced IL-8 release, and these events were interrelated (R(2)=0.95), and apparently connected with the same chemical compounds. PM2.5 fraction, which was enriched in Ca(++) and Mg(++) (from soil dust), and Al, Fe, Zn, Ba Mn, produced cell viability reduction and DNA damage (R(2)=0.73).

Effect of particulate matter, atmospheric gases, temperature, and humidity on respiratory and circulatory diseases' trends in Lisbon, Portugal

This study addresses the significant effects of both well-known contaminants (particles, gases) and less-studied variables (temperature, humidity) on serious, if relatively common, respiratory and circulatory diseases. The area of study is Lisbon, Portugal, and time series of health outcome (daily admissions in 12 hospitals) and environmental data (daily averages of air temperature, relative humidity, PM(10), SO(2), NO, NO(2), CO, and O(3)) have been gathered for 1999-2004 to ascertain (1) whether concentrations of air pollutants and levels of temperature and humidity do interfere on human health, as gauged by hospital admissions due to respiratory and circulatory ailments; and (2) whether there is an effect of population age in such admissions. In general terms, statistically significant (p < 0.001) correlations were found between hospital admissions and temperature, humidity, PM(10), and all gaseous pollutants except CO and NO. Age appears to influence respiratory conditions in association with temperature, whereas, for circulatory conditions, such an influence likely involves temperature as well as the gaseous pollutants NO(2) and SO(2).

The benefits of whole-house in-duct air cleaning in reducing exposures to fine particulate matter of outdoor origin: a modeling analysis

Health risks of fine particle air pollution (PM(2.5)) are an important public health concern that has the potential to be mitigated in part by interventions such as air cleaning devices that reduce personal exposure to ambient PM(2.5). To characterize exposure to ambient PM(2.5) indoors as a function of residential air cleaners, a multi-zone indoor air quality model was used to integrate spatially resolved data on housing, meteorology, and ambient PM(2.5), with performance testing of residential air cleaners to estimate short-term and annual average PM(2.5) of outdoor origin inside residences of three metropolitan areas. The associated public health impacts of reduced ambient PM(2.5) exposure were estimated using a standard health impact assessment methodology. Estimated indoor levels of ambient PM(2.5) varied substantially among ventilation and air cleaning configurations. The median 24-h average indoor-outdoor ratio of ambient PM(2.5) was 0.57 for homes with natural ventilation, 0.35 for homes with central air conditioning (AC) with conventional filtration, and 0.1 for homes with central AC with high efficiency in-duct air cleaner. Median modeled 24-h average indoor concentrations of PM(2.5) of outdoor origin for those three configurations were 8.4, 5.3, and 1.5 microg/m(3), respectively. The potential public health benefits of reduced exposure to ambient PM(2.5) afforded by air cleaning systems were substantial. If the entire population of single-family homes with central AC in the modeling domain converted from conventional filtration to high-efficiency in-duct air cleaning, the change in ambient PM(2.5) exposure is estimated to result in an annual reduction of 700 premature deaths, 940 hospital and emergency room visits, and 130,000 asthma attacks in these metropolitan areas. In addition to controlling emissions from sources, high-efficiency whole-house air cleaner are expected to reduce exposure to particles of outdoor origin and are projected to be an effective means of managing public health impacts of ambient particle pollution.

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.

Emergency admissions for cardiovascular and respiratory diseases and the chemical composition of fine particle air pollution

BACKGROUND

Population-based studies have estimated health risks of short-term exposure to fine particles using mass of PM(2.5) (particulate matter <or= 2.5 microm in aerodynamic diameter) as the indicator. Evidence regarding the toxicity of the chemical components of the PM(2.5) mixture is limited.

OBJECTIVE

In this study we investigated the association between hospital admission for cardiovascular disease (CVD) and respiratory disease and the chemical components of PM(2.5) in the United States.

METHODS

We used a national database comprising daily data for 2000-2006 on emergency hospital admissions for cardiovascular and respiratory outcomes, ambient levels of major PM(2.5) chemical components [sulfate, nitrate, silicon, elemental carbon (EC), organic carbon matter (OCM), and sodium and ammonium ions], and weather. Using Bayesian hierarchical statistical models, we estimated the associations between daily levels of PM(2.5) components and risk of hospital admissions in 119 U.S. urban communities for 12 million Medicare enrollees (>or= 65 years of age).

RESULTS

In multiple-pollutant models that adjust for the levels of other pollutants, an interquartile range (IQR) increase in EC was associated with a 0.80% [95% posterior interval (PI), 0.34-1.27%] increase in risk of same-day cardiovascular admissions, and an IQR increase in OCM was associated with a 1.01% (95% PI, 0.04-1.98%) increase in risk of respiratory admissions on the same day. Other components were not associated with cardiovascular or respiratory hospital admissions in multiple-pollutant models.

CONCLUSIONS

Ambient levels of EC and OCM, which are generated primarily from vehicle emissions, diesel, and wood burning, were associated with the largest risks of emergency hospitalization across the major chemical constituents of PM(2.5).

Gender differences in fetal growth of newborns exposed prenatally to airborne fine particulate matter

Our primary purpose was to assess sex-specific fetal growth reduction in newborns exposed prenatally to fine particulate matter. Only women 18-35 years of age, who claimed to be non-smokers, with singleton pregnancies, without illicit drug use and HIV infection, free from chronic diseases were eligible for the study. A total of 481 enrolled pregnant women who gave birth between 37 and 43 weeks of gestation were included in the study. Prenatal personal exposure to fine particles over 48 h during the second trimester was measured using personal monitors. To evaluate the relationship between the level of PM(2.5) measured over 48 h in the second trimester of pregnancy with those in the first and the third trimesters, a series of repeated measurements in each trimester was carried out in a random subsample of 85 pregnant women. We assessed the effect of PM(2.5) exposure on the birth outcomes (weight, length and head circumference at birth) by multivariable regression models, controlling for potential confounders (maternal education, gestational age, parity, maternal height and prepregnancy weight, sex of infant, prenatal environmental tobacco smoke, and season of birth). Birth outcomes were associated positively with gestational age, parity, maternal height and prepregnancy weight, but negatively with the level of prenatal PM(2.5) exposure. Overall average increase in gestational period of prenatal exposure to fine particles by about 30 microg/m3, i.e., from 25th percentile (23.4 microg/m3) to 75th percentile (53.1 microg/m3) brought about an average birth weight deficit of 97.2g (95% CI: -201, 6.6) and length at birth of 0.7 cm (95% CI: -1.36, -0.04). The corresponding exposure lead to birth weight deficit in male newborns of 189 g (95% CI: -34.2, -343) in comparison to 17g in female newborns; the deficit of length at birth in male infants amounted to 1.1cm (95% CI: -0.11, -2.04). We found a significant interrelationship between self-reported ETS and PM(2.5), however, none of the models showed a significant interaction of both variables. The joint effect of various levels of PM(2.5) and ETS on birth outcomes showed the significant deficit only for the categories of exposure with higher component of PM(2.5). Concluding, the results of the study suggest that observed deficits in birth outcomes are rather attributable to prenatal PM(2.5) exposure and not to environmental tobacco smoke. The study also provided evidence that male fetuses are more sensitive to prenatal PM(2.5) exposure and this should persuade policy makers to consider birth outcomes by gender separately while setting air pollution guidelines.

Population exposure to fine particles and estimated excess mortality in Finland from an East European wildfire episode

Long-range transported particulate matter (PM) air pollution episodes associated with wildfires in the Eastern Europe are relatively common in Southern and Southeastern Finland. In severe cases such as in August-September 2002, the reduced visibility and smell of the smoke, and symptoms such as irritation of eyes and airways experienced by the population raise the issue into the headlines. Because PM air pollution, in general, has been identified as a major health risk, and the exposures are of repeating nature, the issue warrants a risk assessment to estimate the magnitude of the problem. The current work uses the available air quality data in Finland to estimate population exposures caused by one of the worst episodes experienced in this decade. This episode originated from wildfires in Russia, Belarus, Ukraine, and the Baltic countries. The populations of 11 Southern Finnish provinces were exposed between 26 August and 8 September 2002, for 2 weeks to an additional population-weighted average PM(2.5) level of 15.7 microg/m(3). Assuming similar effect on mortality for these particles as observed in epidemiological time series studies on urban particles (0.5%-2% increase in mortality per 10 microg/m(3), central estimate 1%), this exposure level would be associated with 9-34 cases (17 cases central estimate) of additional mortality. Epidemiological evidence specific to particles from biomass combustion is scarce, affecting also the reliability of the current risk assessment. Do the wildfire aerosols exhibit the same level of toxicity as the urban particles? To shed light on this question, it is interesting to look at the exposure data in relationship to the observed daily mortality in Finland, even though the limited duration of the episode allows only for a weak statistical power. The percentage increases observed (0.8%-2.1% per 10 microg/m(3) of fine PM) are in line with the more general estimates for urban PM and those used in the current risk assessment.

Concentrated ambient ultrafine particle exposure induces cardiac changes in young healthy volunteers

RATIONALE

Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis.

OBJECTIVES

To characterize the effects of acute exposure to ambient ultrafine particles in young healthy humans.

METHODS

Nineteen healthy nonsmoking male and female subjects between the ages of 18 and 35 were exposed to filtered air or to an atmosphere in which captured ultrafine (<0.16 microm) particles were concentrated by a factor of up to 20-fold over ambient levels with the use of particle concentrators fitted with size-selective outlets (ultrafine concentrated ambient particles [UFCAPs]). Subjects underwent bronchoalveolar lavage 18 hours after each exposure. Cardiovascular endpoints measured included pulmonary function, clinical chemistry, and hematological parameters, as well as heart rate variability and repolarization indices.

MEASUREMENTS AND MAIN RESULTS

Exposure to UFCAPs was statistically associated with an increase in frequency domain markers of heart rate variability, specifically indicative of elevated vagal input to the heart. Consistent with this finding were increases in the variance associated with the duration of the QT interval. In addition, UFCAP exposure resulted in a significant increase in blood levels of the fibrin degradation product D-dimer as well as a modest elevation in the inflammatory chemokine IL-8 recovered in the lavage fluid.

CONCLUSIONS

These findings show mild inflammatory and prothrombic responses and are suggestive of alterations in cardiac repolarization induced by UFCAP inhalation.

Different effects of PM10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses

PURPOSE

We conducted this study to determine if the preterm risks due to PM(10) exposure vary with the exposure periods during pregnancy. This study was also conducted to estimate the different effects of PM(10) exposure on preterm birth by exposure periods using the extended Cox model with PM(10) exposure as a time-dependent covariate.

METHODS

We studied birth data obtained from the Korea National Statistical office for 374,167 subjects who were delivered between 1998 and 2000 in Seoul, South Korea. We used PM(10) data that was measured hourly to give 24-h averages at 27 monitoring stations in Seoul. The extended Cox model with time-dependent exposure was used to determine if the risk of preterm delivery could be associated with PM(10) exposures for each trimester during pregnancy.

RESULTS

Effect of PM10 exposure prior to the 37 weeks of gestational period was stronger on the risk of premature birth than that posterior to the 37 weeks of gestational weeks. This trend was consistent for each trimester; however, the hazard ratios for preterm delivery associated with PM(10) exposure in the first and third trimester were slightly higher than those of the second trimester.

CONCLUSIONS

The risk of preterm birth associated with exposure to PM(10) differed with the exposure period of the neonates. Therefore, when studying the impact of air pollution exposure during pregnancy, the exposure period during pregnancy should be considered.

Evidence of Health Impacts of Sulfate-and Nitrate-Containing Particles in Ambient Air

Ambient particulate matter (PM) is a complex mixture of inorganic and organic compounds. The U.S. Environmental Protection Agency (EPA) regulates PM as a criteria pollutant and promulgates National Ambient Air Quality Standards for it. The PM indicator is based on mass concentration, unspecified as to chemical composition, for specific size fractions. The numerical standards are based on epidemiologic evidence of associations between the various size-related particle mass concentrations as indicators and excess mortality and cardiorespiratory health effects as endpoints. The U.S. National Research Council has stated that more research is needed to differentiate the apparent health effects associated with different particle chemical constituents. Sulfate and nitrate constitute a significant portion of the particle mass in the atmosphere, but are accompanied by similar amounts of carbonaceous material, along with low concentrations of various species, including bioactive organic compounds and redox cycling metals. Extensive animal and human toxicology data show no significant effects for particles consisting only of sulfate and nitrate compounds at levels in excess of ambient air concentrations. A few epidemiologic studies, including both short-term time-series studies and long-term cohort studies, have included the sulfate content of PM as a specific variable in health effect analyses. There are much less data for nitrate. The results from the epidemiologic studies with PM sulfate are inconsistent. A detailed analysis of the time-series epidemiological studies shows that PM sulfate has a weaker "risk factor" than PM2.5 for health effects. Since sulfate is correlated with PM2.5, this result is inconsistent with sulfate having a strong health influence. However, there are many limitations with these types of studies that warrant caution for any comparison between a chemical component and mass concentration. In total, the epidemiologic and toxicologic evidence provide little or no support for a causal association of PM sulfate and health risk at ambient concentrations. For nitrate-containing PM, virtually no epidemiological data exist. Limited toxicological evidence does not support a causal association between particulate nitrate compounds and excess health risks. There are some possible indirect processes through which sulfate and nitrate in PM may affect health-related endpoints, including interactions with certain metal species and a linkage with production of secondary organic matter. There is insufficient evidence to include or exclude these processes as being potentially important to PM-associated health risk.

Chronic nasal instillation of residual-oil fly ash (ROFA) induces brain lipid peroxidation and behavioral changes in rats

Several epidemiological studies have linked particulate matter exposure to numerous adverse health effects on the respiratory, cardiovascular, and reproductive systems (Braga et al., 1999; Zanobetti et al., 2000; Anderson et al., 2001; Farhat et al., 2005). More recently, ambient levels of black carbon were associated to impaired cognitive function in children (Suglia et al., 2008), suggesting that the central nervous system (CNS) may be a target of air pollutants. The present study was conducted to (a) determine whether chronic residual oil fly ash (ROFA) exposure promotes behavioral changes and lipid peroxidation in rat brain areas, and (b) determine whether N-acetylcysteine (NAC), a general antioxidant, prevents these effects. Forty-five-day-old male Wistar rats were exposed or not to ROFA by intranasal instillation and were treated or not with NAC (150 mg/kg) ip for 30 days. One day later, rats were submitted to the open field test to evaluate the motor/exploratory activities and emotionality followed by decapitation. Striatum and cerebellum were dissected to determine lipid peroxidation by the accumulation of thiobarbituric acid-reactive substances (TBARS). ROFA instillation induced an increase in lipid peroxidation level in striatum (p = .033) and cerebellum (p = .030), as compared with the control group. NAC treatment blocked these changes. ROFA promoted a decrease in the frequency of peripheral walking (p = .006) and a decrease in exploration (p = .001), which were not blocked by N-acetylcysteine. The present study provides evidence that toxic particles, administered by the respiratory route, induce oxidative stress in structures of the central nervous system, as well as behavioral alterations. The administration of NAC reduces lipid peroxidation at the striatum and cerebellum levels, but does not influence behavioral disturbances.

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.

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.

Air pollution and heart rate variability: effect modification by chronic lead exposure

BACKGROUND

Outdoor air pollution and lead exposure can disturb cardiac autonomic function, but the effects of both these exposures together have not been studied.

METHODS

We examined whether higher cumulative lead exposures, as measured by bone lead, modified cross-sectional associations between air pollution and heart rate variability among 384 elderly men from the Normative Aging Study. We used linear regression, controlling for clinical, demographic, and environmental covariates.

RESULTS

We found graded, significant reductions in both high-frequency and low-frequency powers of heart rate variability in relation to ozone and sulfate across the quartiles of tibia lead. Interquartile range increases in ozone and sulfate were associated respectively, with 38% decrease (95% confidence interval = -54.6% to -14.9%) and 22% decrease (-40.4% to 1.6%) in high frequency, and 38% decrease (-51.9% to -20.4%) and 12% decrease (-28.6% to 9.3%) in low frequency, in the highest quartile of tibia lead after controlling for potential confounders. We observed similar but weaker effect modification by tibia lead adjusted for education and cumulative traffic (residuals of the regression of tibia lead on education and cumulative traffic). Patella lead modified only the ozone effect on heart rate variability.

CONCLUSIONS

People with long-term exposure to higher levels of lead may be more sensitive to cardiac autonomic dysfunction on high air pollution days. Efforts to understand how environmental exposures affect the health of an aging population should consider both current levels of pollution and history of lead exposure as susceptibility factors.

Particulate matter (PM(2.5), PM(10-2.5), and PM(10)) and children's hospital admissions for asthma and respiratory diseases: a bidirectional case-crossover study

Epidemiological studies reported adverse effects of air pollution on the prevalence of respiratory diseases in children. The purpose of this study was to examine the association between air pollution and admissions for asthma and other respiratory diseases among children who were younger than 15 yr of age. The study used data on respiratory hospital admissions and air pollutant concentrations, including thoracic particulate matter (PM(10)), fine (PM(2.5)), and coarse (PM(10-2.5)) particulate matter in Zonguldak, Turkey. A bidirectional case-crossover design was used to calculate odds ratios for the admissions adjusted for daily meteorological parameters. Significant increases were observed for hospital admissions in children for asthma, allergic rhinitis (AR), and upper (UPRD) and lower (LWRD) respiratory diseases. All fraction of PM in children showed significant positive associations with asthma admissions. The highest association noted was 18% rise in asthma admissions correlated with a 10-microg/m(3) increase in PM(10-2.5) on the same day of admissions. The adjusted odds ratios for exposure to PM(2.5) with an increment of 10 microg/m(3) were 1.15 and 1.21 for asthma and allergic rhinitis with asthma, respectively. PM(10) exerted significant effects on hospital admissions for all outcomes, including asthma, AR, UPRD, and LWRD. Our study suggested a greater effect of fine and coarse PM on asthma hospital admissions compared with PM(10) in children.

Relationship between indoor, outdoor, and personal fine particle concentrations for individuals with COPD and predictors of indoor-outdoor ratio in Mexico city

Personal exposure and indoor and outdoor exposure to PM(10) and PM(2.5) of 38 individuals with chronic obstructive pulmonary disease (COPD) was characterized from February through November 2000. All participants lived in Mexico City and were selected based on their area of residence southeast (n=15), downtown (n=15), and southwest (n=8). Participants were monitored at home using personal PM(2.5) monitoring devices. Indoor and outdoor levels of PM(10) and PM(2.5) were measured using MiniVol samplers. Concurrent individual exposure measurements, indoor and outdoor levels of PM(2.5), which averaged 38.4 (SD 21.4), 30.6 (SD 15.8), and 30.5 mug/m(3) (SD 19.4), respectively. Indoor PM(2.5) concentrations explained 40% of the variability of personal exposure. In addition, the factors that most affected personal exposure were regular indoor contact with animals, mold, cooking activities, and aerosol use, indicating that internal sources may largely affect individual exposure.

The health impact of common inorganic components of fine particulate matter (PM2.5) in ambient air: a critical review

Ambient air particulate matter (PM) originates as either primary particles emitted directly into the atmosphere from a specific source or as secondary particles produced from atmospheric chemical reactions between precursor gases or between these gases and primary particles. PM can derive from both natural and anthropogenic sources, resulting in a complex chemical mix. The "fine" size mode of ambient PM, designated as PM(2.5), is defined as comprising those particles having aerodynamic diameters below 2.5 microm. While the total mass of PM(2.5) has been associated with adverse human health outcomes, the relationship between these and specific chemical components has not been resolved. This article provides a perspective on the current state of the science concerning health effects from a major group of chemical species found within PM(2.5), namely common inorganic constituents. The specific chemical classes discussed herein are secondary inorganic species, namely, sulfate, nitrate, and acidity, and generally crustal-derived species, namely, phosphate, sodium, potassium, calcium, magnesium, silicon, and aluminum. The article discusses evidence for adverse health effects from inorganic PM(2.5) components within the framework of various caveats surrounding both epidemiology and toxicology assessments. The largest database exists for sulfate, but conclusions that attribute sulfate to health outcomes have not been consistent across all epidemiology studies, and there is a lack of coherence with toxicology studies, which show biological responses only at high levels of exposure. Limited epidemiological and toxicological data for nitrate suggests little or no adverse health effects at current levels. Epidemiological studies specifically identifying crustal components of PM(2.5) suggest that they are not likely, by themselves, to produce a significant health risk, and these components do not have unequivocal biological plausibility from toxicological studies for being significant contributors to adverse health outcomes.

Differentiating the effects of fine and coarse particles on daily mortality in Shanghai, China

The findings on health effects of ambient fine particles (PM2.5) and coarse particles (PM10-2.5) remain inconsistent. In China, PM2.5 and PM10-2.5 are not the criteria air pollutants, and their monitoring data are scarce. There have been no epidemiological studies of health effects of PM2.5 and PM10-2.5 simultaneously in China. We conducted a time series study to examine the acute effects of PM2.5 and PM10-2.5 on daily mortality in Shanghai, China from Mar. 4, 2004 to Dec. 31, 2005. We used the generalized additive model (GAM) with penalized splines to analyze the mortality, air pollution and covariate data. The average concentrations of PM2.5 and PM10-2.5 were 56.4 microg/m3 and 52.3 microg/m3 in our study period, and PM2.5 constituted around 53.0% of the PM10 mass. Compared with the Global Air Quality Guidelines set by World Health Organization (10 microg/m3 for annual mean) and U.S. National Ambient Air Quality Standards (15 microg/m3 for annual mean), the PM2.5 level in Shanghai was much higher. We found that PM2.5 was associated with the death rates from all causes and from cardiorespiratory diseases in Shanghai. We did not find a significant effect of PM10-2.5 on mortality outcomes. A10 microg/m3 increase in the 2-day moving average (lag01) concentration of PM2.5 corresponded to 0.36% (95% CI 0.11%, 0.61%), 0.41% (95% CI 0.01%, 0.82%) and 0.95% (95% CI 0.16%, 1.73%) increase of total, cardiovascular and respiratory mortality. For PM10-2.5, the effects were attenuated and less precise. Our analyses provide the first statistically significant evidence in China that PM2.5 has an adverse effect on population health and strengthen the rationale for further limiting levels of PM2.5 in outdoor air in Shanghai.

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.

Spatiotemporal relationship between particle air pollution and respiratory emergency hospital admissions in Brisbane, Australia

The nature of spatial variation in the relationship between air pollution and health outcomes within a city remains an open and important question. This study investigated the spatial variability of particle matter air pollution and its association with respiratory emergency hospital admissions across six geographic areas in Brisbane, Australia. Data on particles of 10 microm or less in aerodynamic diameter per cubic metre (PM10), meteorological conditions, and daily respiratory emergency hospital admissions were obtained for the period of 1 January 1998 to 31 December 2001. A Poisson generalised linear model was used to estimate the specific effects of PM10 on respiratory emergency hospital admissions for each geographic area. A pooled effect of PM10 was then estimated using a meta-analysis approach for the whole city. The results of this study indicate that the magnitude of the association between particulate matter and respiratory emergency hospital admissions varied across different geographic areas in Brisbane. This relationship appeared to be stronger in areas with heavy traffic. We found an overall increase of 4.0% (95% confidence interval [CI]: 1.1-6.9%) in respiratory emergency hospital admissions associated with an increase of 10 microg /m3 in PM10 in the single pollutant model. The association was weaker but still statistically significant (an increase of 2.6%; 95% CI: 1.0-5.5%) after adjusting for O3, but did not appear to be affected by NO2. The effect estimates of PM10 were generally consistent for three spatial methods used in this study, but appeared to be underestimated if the spatial nature of the data was ignored. Therefore, the spatial variation in the relationship between PM10 and health outcomes needs to be considered when the health impact of air pollution is assessed, particularly for big cities.