Air pollution and cause-specific mortality in Milan, Italy, 1980-1989

Spatiotemporal Variation and Influencing Factors of TSP and Anions in Coastal Atmosphere of Zhanjiang City, China

Water-soluble anions and suspended fine particles have negative impacts on ecosystems and human health, which is a current research hotspot. In this study, coastal suburb, coastal urban area, coastal tourist area, and coastal industrial area were explored to study the spatiotemporal variation and influencing factors of water-soluble anions and total suspended particles (TSP) in Zhanjiang atmosphere. In addition, on-site monitoring, laboratory testing, and analysis were used to identify the difference of each pollutant component at the sampling stations. The results showed that the average concentrations of Cl⁻, NO₃⁻, SO₄²⁻, PO₄³⁻, and TSP were 29.8 μg/m³, 19.6 μg/m³, 45.6 μg/m³, 13.5 μg/m³, and 0.28 mg/m³, respectively. The concentration of Cl⁻, NO₃⁻, PO₄³⁻, and atmospheric TSP were the highest in coastal urban area, while the concentration of SO₄²⁻ was the highest in coastal industrial area. Moreover, there were significantly seasonal differences in the concentration of various pollutants (p < 0.05). Cl⁻ and SO₄²⁻ were high in summer, and NO₃⁻ and TSP were high in winter. Cl⁻, SO₄²⁻, PO₄³⁻, and TSP had significant correlations with meteorological elements (temperature, relative humidity, atmospheric pressure, and wind speed). Besides, the results showed the areas with the most serious air pollution were coastal urban area and coastal industrial area. Moreover, the exhaust emissions from vehicles, urban enterprise emissions, and seawater evaporation were responsible for the serious air pollution in coastal urban area. It provided baseline information for the coastal atmospheric environment quality in Zhanjiang coastal city, which was critical to the mitigation strategies for the emission sources of air pollutants in the future.

Short-Term Exposure to Ambient Air Pollution and Mortality From Myocardial Infarction

BACKGROUND

Short-term exposure to ambient air pollution has been linked to occurrence of myocardial infarction (MI); however, only a limited number of studies investigated its association with death from MI, and the results remain inconsistent.

OBJECTIVES

This study sought to investigate the association of short-term exposure to air pollution across a wide range of concentrations with MI mortality.

METHODS

A time-stratified case-crossover study was conducted to investigate 151,608 MI death cases in Hubei province (China) from 2013 to 2018. Based on each case's home address, exposure to particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5), particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀), sulfur dioxide, nitrogen dioxide (NO₂), carbon monoxide, and ozone on each of the case and control days was assessed as the inverse distance-weighted average concentration at neighboring air quality monitoring stations. Conditional logistic regression models were implemented to quantify exposure-response associations.

RESULTS

Exposure to PM_2.5, PM₁₀, and NO₂ (mean exposure on the same day of death and 1 day prior) was significantly associated with increased odds of MI mortality. The odds associated with PM_2.5 and PM₁₀ exposures increased steeply before a breakpoint (PM_2.5, 33.3 μg/m³; PM₁₀, 57.3 μg/m³) and flattened out at higher exposure levels, while the association for NO₂ exposure was almost linear. Each 10-μg/m³ increase in exposure to PM_2.5 (<33.3 μg/m³), PM₁₀ (<57.3 μg/m³), and NO₂ was significantly associated with a 4.14% (95% confidence interval [CI]: 1.25% to 7.12%), 2.67% (95% CI: 0.80% to 4.57%), and 1.46% (95% CI: 0.76% to 2.17%) increase in odds of MI mortality, respectively. The association between NO₂ exposure and MI mortality was significantly stronger in older adults.

CONCLUSIONS

Short-term exposure to PM_2.5, PM₁₀, and NO₂ was associated with increased risk of MI mortality.

A Combined Citizen Science—Modelling Approach for NO2 Assessment in Torino Urban Agglomeration

The #CHEARIATIRA citizen science campaign was developed in February 2019 in Torino (western part of the Po Valley megacity region). The aim of the campaign was public engagement with measuring NO2 concentrations in an urban area that often exceeds air quality standards. NO2 diffusion tubes were employed by citizens under our supervision. In this paper, we present the main outcomes of a combined approach between the #CHEARIATIRA campaign and the urban dispersion model SIRANE. The results were validated against the available public Air Quality Monitoring Stations (AQMS). The citizens’ passive samplers and the modelled data show a good response in central districts both during the campaign interval and by annual projection. Traffic hotspots and sensitive receptors (schools, hospital) have high concentrations of NO2. Most of the study area (83% of the tubes) is subject to an increased risk of premature death according to epidemiological literature.

Ambient Air Pollution and Mortality After Cardiac Transplantation

BACKGROUND

Heart transplant recipients are at high risk for mortality, with traditional risk scores performing modestly in predicting post-transplant survival, underscoring the importance of as yet unidentified factors in determining prognosis. In this analysis, the association between PM_2.5 exposure levels and survival after heart transplantation were investigated.

OBJECTIVES

This study sought to study the association between PM_2.5 exposure and mortality following heart transplantation.

METHODS

On the basis of the zip code of residence, mortality data in patients who underwent heart transplantation (2004 to 2015) in the United Network for Organ Sharing (UNOS) database were linked with validated estimates of fine particulate matter concentrations (particles with diameter <2.5 μm [PM_2.5]; 1 × 1-km grids) for each calendar year during which a UNOS cardiac transplant recipient was at risk for death. Cox proportional hazard models were used to estimate the relationship between exposure and overall mortality adjusting for recipient, donor, and neighborhood variables.

RESULTS

A total of 21,800 patients with 86,713 patient-years of follow-up was included. Mean age at transplantation was 52.6 ± 12.6 years, 75% were male, 69% were white, and 39% had ischemic etiology of heart failure. Mean annual exposure to PM_2.5 was 10.6 ± 2.3 μg/m³. At a median follow-up of 4.8 (95% confidence interval: 2.0 to 7.8) years, 5,208 patients (23.9%) had died. The estimated mortality hazard ratio, per 10 μg/m³ increment increase in annual PM_2.5 exposure was 1.43 (95% confidence interval: 1.21 to 1.49). After adjusting for 30 recipient, donor, and neighborhood variables, the estimated mortality hazard ratio per 10 μg/m³ increment in annual exposure to PM_2.5 was 1.26 (95% confidence interval: 1.11 to 1.43) relative increase in hazard of mortality. This association was consistent across subgroups.

CONCLUSIONS

This study provides evidence linking air pollution with mortality after heart transplantation. These results suggest an important influence of a key environmental factor in outcomes following heart transplantation, and supports the need for further studies in this population.

Association between sudden unexpected deaths in bathtubs and ambient temperature among elderly Japanese adults: A time-series regression study

BACKGROUND

Sudden unexpected deaths in bathtubs among elderly Japanese adults occur predominantly during the cold season. This study investigated the relationship between these deaths and bathing day temperature among elderly adults in Tokyo.

METHODS

Data for 1408 cases of bath-related deaths from January 1 to December 31, 2015 were obtained from the Tokyo Medical Examiner's Office. We excluded 409 cases for the following reasons: criminal death, injury-related death, suicide, intoxication, non-sudden death, not bathtub-related death, out-of-bathroom death, subject aged under 65 years, undetermined bathing date, institutional housing, and bathing not at subject's home. Ultimately, 999 cases were analyzed. Daily mean temperature data were collected. A time-series regression study was performed to estimate the influence of sex, age, and bathing day temperature. Monthly changes in the population bathing in a bathtub were considered in the model.

RESULTS

The relative risk (RR) of sudden unexpected death in a bathtub was 1.381 for males (95% confidence interval [CI]: 1.218-1.564) compared to females. The RRs were 4.182 (95% CI: 3.523-4.986) and 9.382 (95% CI: 7.836-11.273) among those aged 75-84 years and ≥85 years, respectively, compared to among those aged 65-74 years. The RR increased to 1.092 (95% CI: 1.082-1.102) as the daily mean temperature decreased by 1 °C.

CONCLUSION

Sudden unexpected death in a bathtub correlated with bathing day temperature among elderly Japanese adults, and extremely low temperature, male sex, and older age increased the risk of such death. Our findings provide insight into preventing sudden unexpected deaths in bathtubs.

Effects of ambient temperature on myocardial infarction: A systematic review and meta-analysis

Previous studies have suggested that ambient temperature is associated with the mortality and morbidity of myocardial infarction (MI) although consistency among these investigations is lacking. We performed a meta-analysis to investigate the relationship between ambient temperature and MI. The PubMed, Web of Science, and China National Knowledge Infrastructure databases were searched back to August 31, 2017. The pooled estimates for different temperature exposures were calculated using a random-effects model. The Cochran's Q test and coefficient of inconsistency (I²) were used to evaluate heterogeneity, and the Egger's test was used to assess publication bias. The exposure-response relationship of temperature-MI mortality or hospitalization was modeled using random-effects meta-regression. A total of 30 papers were included in the review, and 23 studies were included in the meta-analysis. The pooled estimates for the relationship between temperature and the relative risk of MI hospitalization was 1.016 (95% confidence interval [CI]: 1.004-1.028) for a 1 °C increase and 1.014 (95% CI: 1.004-1.024) for a 1 °C decrease. The pooled estimate of MI mortality was 1.639 (95% CI: 1.087-2.470) for a heat wave. The heterogeneity was significant for heat exposure, cold exposure, and heat wave exposure. The Egger's test revealed potential publication bias for cold exposure and heat exposure, whereas there was no publication bias for heat wave exposure. An increase in latitude was associated with a decreased risk of MI hospitalization due to cold exposure. The association of heat exposure and heat wave were immediate, and the association of cold exposure were delayed. Consequently, cold exposure, heat exposure, and exposure to heat waves were associated with an increased risk of MI. Further research studies are required to understand the relationship between temperature and MI in different climate areas and extreme weather conditions.

Summertime extreme heat events and increased risk of acute myocardial infarction hospitalizations

Few studies have examined the association between exposure to extreme heat events and risk of acute myocardial infarction (AMI) or demonstrated which populations are most vulnerable to the effects of extreme heat. We defined extreme heat events as days when the daily maximum temperature (TMAX) exceeded the location- and calendar day-specific 95th percentile of the distribution of daily TMAX during the 30-year baseline period (1960-1989). We used a time-stratified case-crossover design to analyze the association between exposure to extreme heat events and risk of hospitalization for AMI in the summer months (June-August) with 0, 1, or 2 lag days. There were a total of 32,670 AMI hospitalizations during the summer months in Maryland between 2000 and 2012. Overall, extreme heat events on the day of hospitalization were associated with an increased risk of AMI (lag 0 OR=1.11; 95% CI: 1.05-1.17). Results considering lag periods immediately before hospitalization were comparable, but effect estimates varied among several population subgroups. As extreme weather events are expected to become more frequent and intense in response to our changing climate, community-specific adaptation strategies are needed to account for the differential susceptibility across ethnic subgroups and geographic areas.

Impact of air quality guidelines on COPD sufferers

Background

COPD is one of the leading causes of morbidity and mortality in both high- and low-income countries and a major public health burden worldwide. While cigarette smoking remains the main cause of COPD, outdoor and indoor air pollution are important risk factors to its etiology. Although studies over the last 30 years helped reduce the values, it is not very clear if the current air quality guidelines are adequately protective for COPD sufferers.

Objective

This systematic review was to summarize the up-to-date literature on the impact of air pollution on the COPD sufferers.

Methods

PubMed and Google Scholar were utilized to search for articles related to our study’s focus. Search terms included “COPD exacerbation”, “air pollution”, “air quality guidelines”, “air quality standards”, “COPD morbidity and mortality”, “chronic bronchitis”, and “air pollution control” separately and in combination. We focused on articles from 1990 to 2015. We also used articles prior to 1990 if they contained relevant information. We focused on articles written in English or with an English abstract. We also used the articles in the reference lists of the identified articles.

Results

Both short-term and long-term exposures to outdoor air pollution around the world are associated with the mortality and morbidity of COPD sufferers even at levels below the current air quality guidelines. Biomass cooking in low-income countries was clearly associated with COPD morbidity in adult nonsmoking females.

Conclusion

There is a need to continue to improve the air quality guidelines. A range of intervention measures could be selected at different levels based on countries’ socioeconomic conditions to reduce the air pollution exposure and COPD burden.

Short-term exposure to environmental parameters and onset of ST elevation myocardial infarction. The CARDIO-ARSIF registry

BACKGROUND

Environmental parameters have been reported to be triggers of acute myocardial infarction (MI). However, the individual role of each parameter is unknown. We quantified the respective association of climate parameters, influenza epidemics and air pollutants with the onset of ST elevation MI (STEMI) in Paris and the surrounding small ring.

METHODS

Data from the CARDIO-ARSIF registry (Paris and small ring STEMI population), Météo France (Climate), GROG (Influenza epidemic) and AIRPARIF (Air Pollution) were analyzed. The association between short-term exposure (1 day lag time) to environmental parameters and STEMI occurrence was quantified by time series modeling of daily STEMI count data, using Poisson regression with generalized additive models.

RESULTS

Between 2003 and 2008, 11,987 <24H STEMI confirmed by angiography were adjudicated. There was a 5.0% excess relative risk (ERR) of STEMI per 10°C decrease in maximal temperature (95% CI 2.1% to 7.8%: p=0.001) and an 8.9% ERR (95% CI 3.2% to 14.9%: p=0.002) during an influenza epidemic after adjustment on week-days and holidays. Associations were consistent when short-term exposure varied from 2 to 7 days. Associations between lower temperatures and STEMI were stronger in magnitude when influenza epidemic was present. Short-term exposure to climatic parameters or pollutants was not associated with STEMI.

CONCLUSIONS

The present population based registry of STEMI suggests that short-term exposure to lower temperature and influenza epidemic is associated with a significant excess relative risk of STEMI. Subjects at risk for MI may benefit from specific protections against cold temperature and influenza infection.

Short-term effect of temperature on daily emergency visits for acute myocardial infarction with threshold temperatures

BACKGROUND

The relationship between temperature and myocardial infarction has not been fully explained. In this study, we identified the threshold temperature and examined the relationship between temperature and emergency admissions due to MI in Korea.

METHODS

Poisson generalized additive model analyses were used to assess the short-term effects of temperature (mean, maximum, minimum, diurnal) on MI emergency visits, after controlling for meteorological variable and air pollution (PM10, NO2). We defined the threshold temperature when the inflection point showed a statistically significant difference in the regression coefficients of the generalized additive models (GAMs) analysis. The analysis was performed on the following subgroups: geographical region, gender, age (<75 years or ≥ 75 years), and MI status (STEMI or non-STEMI).

RESULTS

The threshold temperatures during heat exposure were for the maximum temperature as 25.5-31.5°C and for the mean temperature as 27.5-28.5°C. The threshold temperatures during cold exposure were for the minimum temperature as -2.5-1.5°C. Relative risks (RRs) of emergency visits above hot temperature thresholds ranged from 1.02 to 1.30 and those below cold temperature thresholds ranged from 1.01 to 1.05. We also observed increased RRs ranged from 1.02 to 1.65 of emergency visits when temperatures changes on a single day or on successive days.

CONCLUSIONS

We found a relationship between temperature and MI occurrence during both heat and cold exposure at the threshold temperature. Diurnal temperature or temperature change on successive days also increased MI risk.

Does temperature enhance acute mortality effects of ambient particle pollution in Tianjin City, China

Only a few epidemiological studies have explored whether there were interactive effects between temperature and particulate matter <10μm in aerodynamic diameter (PM(10)) on mortality, especially in Asian countries. The present study used time-series analysis to explore the modification effects of temperature on the association between PM(10) and the cause-specific mortality for cardiovascular, respiratory, cardiopulmonary, stroke and ischemic heart diseases (IHD), as well as non-accidental mortality in Tianjin between 2007 and 2009. Results showed that the PM(10) effects were stronger on high temperature level days than that on low temperature level days. The interactions between PM(10) and temperature were statistically significant on cardiovascular, cardiopulmonary, and IHD mortalities. The effect estimates per 10-μg/m(3) increase in PM(10) concentrations at the moving average of lags 0 and 1 day in high temperature level were 0.62% (95% confidence interval (CI): 0.27, 0.97) for non-accidental, 0.92% (0.47, 1.36) for cardiovascular, 0.74% (-0.33, 1.82) for respiratory, 0.89% (0.47, 1.32) for cardiopulmonary, 0.65% (0.00, 1.31) for stroke and 1.20% (0.63, 1.78) for IHD mortalities. In addition, the PM(10) effects on high temperature level days were stronger on older (≥65 years) compared with younger subjects (<65 years). This suggests that the modifying effects of the temperature should be considered when analyzing health impacts of ambient PM(10).

Comparative effects of inhaled diesel exhaust and ambient fine particles on inflammation, atherosclerosis, and vascular dysfunction

Ambient air PM(2.5) (particulate matter less than 2.5 mum in diameter) has been associated with cardiovascular diseases (CVDs), but the underlying mechanisms affecting CVDs are unknown. The authors investigated whether subchronic inhalation of concentrated ambient PM(2.5) (CAPs), whole diesel exhaust (WDE), or diesel exhaust gases (DEGs) led to exacerbation of atherosclerosis, pulmonary and systemic inflammation, and vascular dysfunction; and whether DEG interactions with CAPs alter cardiovascular effects. ApoE(-/-) mice were simultaneously exposed via inhalation for 5 hours/day, 4 days/week, for up to 5 months to one of five different exposure atmospheres: (1) filtered air (FA); (2) CAPs (105 microg/m(3)); (3) WDE (DEP = 436 microg/m(3)); (4) DEG (equivalent to gas levels in WDE group); and (5) CAPs+DEG (PM(2.5): 113 microg/m(3); with DEG equivalent to WDE group). After 3 and 5 months, lung lavage fluid and blood sera were analyzed, and atherosclerotic plaques were quantified by ultrasound imaging, hematoxylin and eosin (H&E stain), and en face Sudan IV stain. Vascular functions were assessed after 5 months of exposure. The authors showed that (1) subchronic CAPs, WDE, and DEG inhalations increased serum vascular cell adhesion molecule (VCAM)-1 levels and enhanced phenylephrine (PE)-induced vasoconstriction; (2) for plaque exacerbation, CAPs > WDE > DEG = FA, thus PM components (not present in WDE) were responsible for plaque development; (3) atherosclerosis can exacerbated through mechanistic pathways other than inflammation and vascular dysfunction; and (4) although there were no significant interactions between CAPs and DEG on plaque exacerbation, it is less clear whether the effects of CAPs on vasomotor dysfunction and pulmonary/systemic inflammation were enhanced by the DEG coexposure.

Short term effects of temperature on risk of myocardial infarction in England and Wales: time series regression analysis of the Myocardial Ischaemia National Audit Project (MINAP) registry

OBJECTIVE

To examine the short term relation between ambient temperature and risk of myocardial infarction.

DESIGN

Daily time series regression analysis.

SETTING

15 conurbations in England and Wales.

PARTICIPANTS

84,010 hospital admissions for myocardial infarction recorded in the Myocardial Ischaemia National Audit Project during 2003-6 (median 57 events a day).

MAIN OUTCOME MEASURES

Change in risk of myocardial infarction associated with a 1 degrees C difference in temperature, including effects delayed by up to 28 days.

RESULTS

Smoothed graphs revealed a broadly linear relation between temperature and myocardial infarction, which was well characterised by log-linear models without a temperature threshold: each 1 degrees C reduction in daily mean temperature was associated with a 2.0% (95% confidence interval 1.1% to 2.9%) cumulative increase in risk of myocardial infarction over the current and following 28 days, the strongest effects being estimated at intermediate lags of 2-7 and 8-14 days: increase per 1 degrees C reduction 0.6% (95% confidence interval 0.2% to 1.1%) and 0.7% (0.3% to 1.1%), respectively. Heat had no detrimental effect. Adults aged 75-84 and those with previous coronary heart disease seemed more vulnerable to the effects of cold than other age groups (P for interaction 0.001 or less in each case), whereas those taking aspirin were less vulnerable (P for interaction 0.007).

CONCLUSIONS

Increases in risk of myocardial infarction at colder ambient temperatures may be one driver of cold related increases in overall mortality, but an increased risk of myocardial infarction at higher temperatures was not detected. The risk of myocardial infarction in vulnerable people might be reduced by the provision of targeted advice or other interventions, triggered by forecasts of lower temperature.

Particulate air pollution and coronary heart disease

PURPOSE OF REVIEW

Air pollution poses a significant health risk. The article focuses on the adverse effects of air pollution on the cardiovascular system.

RECENT FINDINGS

Short-term and long-term studies clearly indicate that relatively modest exposures to particulate matter in the ambient air are associated with increased morbidity and mortality due to coronary heart disease. In humans, inhalational exposure to particulate air pollutants decreases heart rate variability, causes ST-segment depression and endothelial dysfunction, increases blood pressure and blood coagulability, and accelerates the progression of atherosclerosis. Mechanisms of air pollution-induced cardiotoxicity include increased generation of reactive oxygen species followed by activation of proinflammatory and prothrombotic pathways. In experimental settings, ultrafine air pollutants instilled directly into the cardiac vasculature depress cardiac contractility and decrease coronary flow. Both effects are attenuated by the use of a free radical scavenger.

SUMMARY

Reactive oxygen species-related mechanisms of air pollution cardiotoxicity might become a valid target in developing new pharmacological strategies aimed at decreasing adverse effects of air pollution during extreme episodes (fires, earthquakes, industrial accidents, acts of terrorism). Educating patients and the general population on the negative cardiovascular effects of air pollution might be helpful in decreasing the risk of developing air pollution-related coronary heart disease.

Seasonal Variation in Onset of Myocardial Infarction—A 7‐year single‐center study in Italy

Like many other serious acute cardiovascular and cerebrovascular events, acute myocardial infarction (AMI) shows seasonal variation, being most frequent in the winter. We sought to investigate whether age, gender, and hypertension influence this pattern. We studied 4014 (2259 male and 1755 female) consecutive patients with AMI presenting to St. Anna Hospital of Ferrara, Italy between January 1998 and December 2004. Some 1131 (28.2%) of the AMI occurred in persons <65 yrs of age, and 2883 (71.8%) in those > or =65 yrs of age. AMI was over-represented in males (82% in the <65 yr group vs. 56.6% in the > or =65 yr group (chi2=13.99; p<0.001). Hypertension had been previously documented in 964 (24%) of the cases. There were 691 (17.2%) fatal case outcomes; fatal outcomes were significantly higher among the 3054 normotensive (n=614 or 20.1%) than the 964 hypertensive cases (n=77 or 8%; chi2=74.94, p<0.001). AMIs were most frequent in the winter (n=1076 or 26.8% of all the events) and least in the summer (n=924 or 23.0% of all the events; chi2=12.36, p=0.007). The greatest number of AMIs occurred in December (n=379 or 9.44%), and the lowest number in September (n=293 or 7.3%; chi2=11.1, p=0.001). Inferential chronobiological (Cosinor) analysis identified a significant annual pattern in AMI in those > or =65 yrs of age, with a peak between December and February-January for the total sample (p<0.005), January for the sample of males (p=0.014), February for fatal infarctions (p=0.017), and December for non-fatal infarctions (p=0.006). No such temporal variations were detected in any of these categories in those <65 yrs of age. The annual pattern in AMI was also verified by Cosinor analysis in the following hypertensive subgroups: hypertensive males (n=552: January, p=0.014), non-fatal infarctions in hypertensive patients (n=887: January, p=0.018), and elderly normotensives (n=1556: November, p=0.007).

Ambient particulates alter vascular function through induction of reactive oxygen and nitrogen species

Previous studies have shown a link between inhaled particulate matter (PM) exposure in urban areas and susceptibility to cardiovascular diseases. Although an oxidative stress pathway is strongly implicated, the locus of generation of reactive oxygen species (ROS) and the mechanisms by which these radicals exert their effects remain to be characterized. To test the hypothesis that exposure to environmentally relevant inhaled concentrated ambient PM (CAPs) enhances atherosclerosis through induction of vascular ROS and reactive nitrogen species. High-fat chow fed apolipoprotein E(-/-) mice were exposed to CAPs of less than 2.5 microm (PM(2.5)) or filtered air (FA), for 6 h/day, 5 days/week, for 4 months in Manhattan, NY. Atherosclerotic lesions were analyzed by histomorphometricly. Vascular reactivity, superoxide generation, mRNA expression of NADPH (nicotinamide adenine dinucleotide phosphate, reduced) oxidase subunits, inducible nitric oxide synthase, endothelial nitric oxide synthase, and GTP cyclohydrolase I were also assessed. Manhattan PM(2.5) CAPs were characterized by higher concentrations of organic and elemental carbon. Analysis of vascular responses revealed significantly decreased phenylephrine constriction in CAPs-exposed mice, which was restored by a soluble guanine cyclase inhibitor 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one. Vascular relaxation to A23187, but not to acetylcholine, was attenuated in CAPs mice. Aortic expression of NADPH oxidase subunits (p47(phox) and rac1) and iNOS were markedly increased, paralleled by increases in superoxide generation and extensive protein nitration in the aorta. The composite plaque area of thoracic aorta was significantly increased with pronounced macrophage infiltration and lipid deposition in the CAPs mice. CAPs exposure in Manhattan alters vasomotor tone and enhances atherosclerosis through NADPH oxidase dependent pathways.

Health effects of ambient air pollution--recent research development and contemporary methodological challenges

Exposure to high levels of air pollution can cause a variety of adverse health outcomes. Air quality in developed countries has been generally improved over the last three decades. However, many recent epidemiological studies have consistently shown positive associations between low-level exposure to air pollution and health outcomes. Thus, adverse health effects of air pollution, even at relatively low levels, remain a public concern. This paper aims to provide an overview of recent research development and contemporary methodological challenges in this field and to identify future research directions for air pollution epidemiological studies.

Age, gender, and hormonal status modulate the vascular toxicity of the diesel exhaust extract phenanthraquinone

Inhaled airborne pollutants such as particulate matter increase the susceptibility to adverse health consequences and cardiovascular events. Diesel exhaust contributes significantly to the ambient particle pollution burden. The purpose of this investigation was to determine if exposure to a common component of diesel exhaust, phenanthraquinone (PQ), impairs endothelium-dependent vasodilation of the femoral principal nutrient artery and to determine whether age, gender, and/or hormonal status alter the putative effects of PQ on vasodilation. Vasodilation to acetylcholine (ACh) was assessed in vitro in intact control (age 6, 14, and 24 mo) and ovariectomized (age 6, 14, and 24 mo) female rats and intact (age 6 and 24 mo) male rats. Gender did not influence vasodilator capacity of the femoral principal nutrient artery, and there was an age-related decline in endothelium-dependent vasodilation in both female and male 24-mo-old rats. Exposure to PQ elicited a gender-specific affect in 6-mo-old rats; i.e., vasodilation was impaired 63% in male rats but had no effect in female rats. Exposure to PQ abolished vasodilation in 14- and 24-mo-old rats of both genders, and ovariectomy compromised vasodilator responsiveness to ACh in all age groups. The data demonstrate a vasoprotective mechanism in young female rats that may be related to endogenous ovarian hormones and provides evidence that suggests certain subsets of the population (e.g., elderly, males, and postmenopausal women) may be more susceptible to the adverse consequences of airborne pollutants.

Animal models of human pneumonia

Pneumonia is a medical and public health priority, and advances against this disease will require improved knowledge of biological mechanisms. Human pneumonia is modeled with experimental infections of animals, most frequently mice. Mouse models are leading to important discoveries relevant to pneumonia, but their limitations must be carefully considered. Several approaches to establishing pneumonia in mice have been developed, and each has specific strengths and weaknesses. Similarly, procedures for characterizing microbial and host responses to infection have unique advantages and disadvantages. Mice are not small humans, and the applicability of results from murine models to human disease depends on understanding the similarities and differences between species. Additional considerations such as mouse strain, microbe strain, and prior mouse-microbe interactions also influence the design and interpretation of experiments. Results from studies of pneumonia in animals, combined with complementary basic and translational studies, are elucidating mechanisms responsible for susceptibility to and pathophysiology of lung infection.

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.

Effect of diesel exhaust particles on mRNA expression of viral and bacterial receptors in rat lung epithelial L2 cells

Epidemiological studies have shown that particulate matter (PM) is associated with adverse respiratory health effects. Although infection in the respiratory organ is one of the most important health risks the association of infection with PM is not fully understood. As we had hypothesized that diesel exhaust particles (DEP), one of the major component of PM, may induce the expression of receptors for viruses and bacteria at invasion sites, we studied the effect of DEP on the mRNA expression of intercellular adhesion molecule-1 (ICAM-1), low-density lipoprotein (LDL) and platelet-activating factor (PAF) receptors, which are invasion sites of virus and bacteria, on rat lung epithelial cells. The real-time quantitative polymerase chain reaction (PCR) method was used for the evaluation. All of these mRNAs were up-regulated by 3, 10, and 30 microg/ml of DEP in a concentration-dependent manner. The up-regulation of each was associated with the mRNA expression of heme oxygenase-1 (HO-1), a marker of oxidative stress. Our present results show that DEP up-regulated the mRNA expression of viral and bacterial receptors. This up-regulation might be associated with DEP-induced oxidative stress. These results thus suggest that DEP may enhance the risk of pneumonia by increasing the density of bacterial and viral invasion sites in the lungs.

Survival analysis to estimate association between short-term mortality and air pollution

BACKGROUND

Ecologic studies are commonly used to report associations between short-term air pollution and mortality. In such studies, the unit of observation is the day rather than the individual. Moreover, individual data on the subjects are rarely available, which limits the assessment of individual risk factors. These associations can also be investigated using case-crossover studies. However, by definition, individual risk factors are not studied, and such studies analyze only dead subjects, which limits the statistical power.

OBJECTIVE

We suggest that the survival analysis is more suitable when cohorts are examined with a time-dependent ecologic exposure. To our knowledge, to date this type of analysis has never been proposed.

DESIGN, PARTICIPANTS, MEASUREMENTS

In the present study we used a Cox proportional hazards model to investigate the distribution over time of the short-term effect of black smoke and sulfur dioxide in 439 nonaccidental and 158 cardiorespiratory deaths among the 1,469 subjects of the Personnes Agées QUID (PAQUID) cohort in Bordeaux, France. The model has a delayed entry and a polynomial distributed lag from 0 to 5 days. Results are adjusted for individual risk factors, temperature, relative humidity, weekday, season, influenza epidemics, and a time function to control temporal trends.

RESULTS

We identified a positive and significant association between cardiorespiratory mortality and black smoke, with a 24% increase in deaths 3 days after a 10-microg/m3 increase in black smoke (95% confidence interval, 4-47%).

CONCLUSIONS

We conclude that the Cox proportional hazards model with time-dependent covariates is very suitable to investigate simultaneously the short-term effect of air pollution on health and the effect of individual risk factors on a cohort study.

Seasonal confounding in air pollution and health time-series studies: effect on air pollution effect estimates

A major statistical challenge in air pollution and health time-series studies is to adequately control for confounding effects of time-varying covariates. Daily health outcome counts are most commonly analysed by Poisson regression models, adjusted for overdispersion, with air pollution levels included as a linear predictor and smooth functions for calendar time and weather variables to adjust for time-varying confounders. Various smoothers have been used so far, but the optimal strategy for choosing smoothers and their degree of smoothing remains controversial. In this work, we evaluate the performance of various smoothers with different criteria for choosing the degree of smoothing in terms of bias and efficiency of the air pollution effect estimate in a simulation study. The evaluated approaches were also applied to real mortality data from 22 European cities. The simulation study imitated a multi-city study. Data were generated from a fully parametric model. Model selection methods which optimize prediction may lead to increased biases in the air pollution effect estimate. Minimization of the absolute value of the sum of the partial autocorrelation function of the model's residuals (PACF), as a criterion to choose the degree of smoothness, gave the smallest biases. The penalized splines (PS) method with a large number of effective dfs (e.g. 8-12 per year) could be used as the basic, relatively conservative, analysis whereas the PS and natural splines in combination with PACF could be applied to provide a reasonable range of the effect estimate.

The German view: effects of nitrogen dioxide on human health--derivation of health-related short-term and long-term values

The presented overview concerning health relevant effects caused by nitrogen dioxide (NO2) resumes the current state of results from animal experiments and human studies (epidemiology and short-term chambers studies). NO2 concentrations applied in animal experiments were mostly considerably higher than in ambient air. Therefore, short- and long-term limit values were derived from human data. Experimental studies conducted with humans demonstrate effects after short-term exposure to concentrations at or above 400 microg NO2/m3. Effects on patients with light asthma could not be observed after short-term exposure to concentrations below 200 microg/m3. On basis of epidemiological long-term studies a threshold below which no effect on human health is expected could not be specified. Two short-term limit values have been proposed to protect public health: a 1-h value of 100 microg/m3 and a 24-h mean value of 50 microg/m3. Due to the limitations of epidemiological studies to disentangle effects of single pollutants, a long-term limit value cannot be easily derived. However, applying the precautionary principle, it is desirable to adopt an annual mean of 20 microg NO2/m3 as a long-term mean standard to protect public health.

Sensitivity of the estimated air pollution-respiratory admissions relationship to statistical model choice

The objective of this study was to demonstrate the methodological shortcomings of currently available analytical methods for single-city time series data. We analyzed daily Chronic Obstructive Pulmonary Disease (COPD) and daily asthma hospital admissions in Melbourne, Australia from July 1989 to December 1992. Air pollution data comprised nitrogen dioxide, ozone and sulphur dioxide and air particles index consistent with particulates between 0.1 and 1 microm in aerodynamic diameter. Statistical analyses were performed using generalized linear models, generalized additive models, Poisson autoregressive models and transitional regression models. The estimated effect of nitrogen dioxide on COPD hospital admissions was similar across the different statistical models, RR = 1.06 (95% CI 1.01-1.11). Similarly the estimated effect of nitrogen dioxide on asthma hospital admissions was also consistent, RR = 1.05 (95% CI 1.01-1.09). However, the effects of ozone, air particles index and sulphur dioxide were highly sensitive to model specification for both COPD and asthma hospital admissions. In single-city studies of air pollution and respiratory disease, very different conclusions can be drawn from competing models. Furthermore, real time series data have greater complexity than any of the commonly-used existing models allow. Consequently, single-city studies should use several statistical models to demonstrate the stability of estimated effects.

Potential role of ultrafine particles in associations between airborne particle mass and cardiovascular health

Numerous epidemiologic time-series studies have shown generally consistent associations of cardiovascular hospital admissions and mortality with outdoor air pollution, particularly mass concentrations of particulate matter (PM) < or = 2.5 or < or = 10 microm in diameter (PM2.5, PM10). Panel studies with repeated measures have supported the time-series results showing associations between PM and risk of cardiac ischemia and arrhythmias, increased blood pressure, decreased heart rate variability, and increased circulating markers of inflammation and thrombosis. The causal components driving the PM associations remain to be identified. Epidemiologic data using pollutant gases and particle characteristics such as particle number concentration and elemental carbon have provided indirect evidence that products of fossil fuel combustion are important. Ultrafine particles < 0.1 microm (UFPs) dominate particle number concentrations and surface area and are therefore capable of carrying large concentrations of adsorbed or condensed toxic air pollutants. It is likely that redox-active components in UFPs from fossil fuel combustion reach cardiovascular target sites. High UFP exposures may lead to systemic inflammation through oxidative stress responses to reactive oxygen species and thereby promote the progression of atherosclerosis and precipitate acute cardiovascular responses ranging from increased blood pressure to myocardial infarction. The next steps in epidemiologic research are to identify more clearly the putative PM casual components and size fractions linked to their sources. To advance this, we discuss in a companion article (Sioutas C, Delfino RJ, Singh M. 2005. Environ Health Perspect 113:947-955) the need for and methods of UFP exposure assessment.

Particulate air pollution and the rate of hospitalization for congestive heart failure among medicare beneficiaries in Pittsburgh, Pennsylvania

The authors used a case-crossover approach to evaluate the association between ambient air pollution and the rate of hospitalization for congestive heart failure among Medicare recipients (aged > or =65 years) residing in Allegheny County (Pittsburgh area), Pennsylvania, during 1987-1999. They also explored effect modification by age, gender, and specific secondary diagnoses. During follow-up, 55,019 patients were admitted with a primary diagnosis of congestive heart failure. In single-pollutant models, particulate matter with an aerodynamic diameter of <10 microm (PM(10)), carbon monoxide, nitrogen dioxide, and sulfur dioxide-but not ozone-were positively and significantly associated with the rate of admission on the same day. The strongest associations were observed with carbon monoxide, nitrogen dioxide, and PM(10). The associations with carbon monoxide and nitrogen dioxide were the most robust in two-pollutant models, remaining statistically significant even after adjusting for other pollutants. Patients with a recent myocardial infarction were at greater risk of particulate-related admission; otherwise, there was no significant effect modification by age, gender, or other secondary diagnoses. These results suggest that short-term elevations in air pollution from traffic-related sources may trigger acute cardiac decompensation in heart failure patients and that those with certain comorbid conditions may be more susceptible to these effects.

Estimating the exposure-response relationships between particulate matter and mortality within the APHEA multicity project

Several studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of theses studies linear nonthreshold relations were assumed. We investigated the exposure-response association between ambient particles and mortality in the 22 European cities participating in the APHEA (Air Pollution and Health--A European Approach) project, which is the largest available European database. We estimated the exposure-response curves using regression spline models with two knots and then combined the individual city estimates of the spline to get an overall exposure-response relationship. To further explore the heterogeneity in the observed city-specific exposure-response associations, we investigated several city descriptive variables as potential effect modifiers that could alter the shape of the curve. We conclude that the association between ambient particles and mortality in the cities included in the present analysis, and in the range of the pollutant common in all analyzed cities, could be adequately estimated using the linear model. Our results confirm those previously reported in Europe and the United States. The heterogeneity found in the different city-specific relations reflects real effect modification, which can be explained partly by factors characterizing the air pollution mix, climate, and the health of the population.

Short-Term Effects of Air Pollution on Total and Cardiovascular Mortality

BACKGROUND

Air pollution is associated with total mortality. This association may be confounded by uncontrolled time-varying risk factors such as influenza epidemics.

METHODS

We analyzed independent data on influenza epidemics from 7 European cities that also had data on mortality associated with particulates (PM10). We used 10 methods to control for epidemics (5 derived from influenza data and 5 from respiratory mortality series) and compared those results with analyses that did not control for these epidemics.

RESULTS

Adjustment for influenza epidemics increased the PM10 effect estimate in most cases (% change in the pooled regression coefficient: -1.9 to 38.9 for total mortality and 1.3 to 25.5 for cardiovascular mortality). A 10-microg/m increase in PM10 concentrations (lag 0-1) was associated with a 0.48% (95% confidence interval=0.27-0.70%) increase in daily mortality unadjusted for influenza epidemics, whereas under the various methods to control for epidemics the increase ranged from 0.45% (0.26-0.69%) to 0.67% (0.46-0.89%). The corresponding figures for cardiovascular mortality were 0.85% (0.53-1.18%) with no adjustment and from 0.86% (0.53-1.19%) to 1.06% (0.74-1.39%) with the methods of control.

CONCLUSIONS

The association between air pollution and mortality is not weakened by control for influenza epidemic irrespective of the method used. To adjust for influenza epidemics, one can use methods based on respiratory mortality counts instead of counts of influenza cases if the latter are not available. However, adjustment for influenza by any method tested did not markedly alter the air pollution effect estimate.

Temperature, air pollution, and mortality from myocardial infarction in São Paulo, Brazil

An increase in daily mortality from myocardial infarction has been observed in association with meteorological factors and air pollution in several cities in the world, mainly in the northern hemisphere. The objective of the present study was to analyze the independent effects of environmental variables on daily counts of death from myocardial infarction in a subtropical region in South America. We used the robust Poisson regression to investigate associations between weather (temperature, humidity and barometric pressure), air pollution (sulfur dioxide, carbon monoxide, and inhalable particulate), and the daily death counts attributed to myocardial infarction in the city of São Paulo in Brazil, where 12,007 fatal events were observed from 1996 to 1998. The model was adjusted in a linear fashion for relative humidity and day-of-week, while nonparametric smoothing factors were used for seasonal trend and temperature. We found a significant association of daily temperature with deaths due to myocardial infarction (P < 0.001), with the lowest mortality being observed at temperatures between 21.6 and 22.6 degrees C. Relative humidity appeared to exert a protective effect. Sulfur dioxide concentrations correlated linearly with myocardial infarction deaths, increasing the number of fatal events by 3.4% (relative risk of 1.03; 95% confidence interval = 1.02-1.05) for each 10 microg/m(3) increase. In conclusion, this study provides evidence of important associations between daily temperature and air pollution and mortality from myocardial infarction in a subtropical region, even after a comprehensive control for confounding factors.

Predicted health impacts of urban air quality management

STUDY OBJECTIVE

The 1995 UK Environment Act required local authorities to review air quality and, where UK National Air Quality Strategy objectives (except ozone) are likely to be exceeded in 2005, to declare local air quality management areas and prepare action plans. This study modelled the impacts on health of reductions from current levels of PM(10) to these objectives.

DESIGN

The framework for conducting quantified health impact assessment assessed causality, then, if appropriate, examined the shape and magnitude of the exposure-response relations. The study modelled declines in pollution to achieve the objectives, then modelled the numbers of deaths and admissions affected if air pollution declined from existing levels to meet the objectives, using routine data.

SETTING

Westminster, central London.

MAIN RESULTS

Attaining the 2004 PM(10) 24 hour objective in Westminster results in 1-21 lives no longer shortened in one year (annual deaths 1363). Reducing exceedences from 35 to seven almost doubles the estimates. The 2009 objective for the annual mean requires a substantial reduction in PM(10), which would delay 8-20 deaths. About 20 respiratory and 14-20 circulatory admissions would be affected and around 5% of emergency hospital attendances for asthma by attaining the lower annual mean target. The effects of long term exposure to particulates may be an order of magnitude higher: models predict about 24 deaths are delayed by reaching the 2004 annual target (40 microg/m(3)([gravimetric])) and a hundred deaths by reducing annual mean PM(10) to 20 microg/m(3)([gravimetric]).

CONCLUSIONS

Modelling can be used to estimate the potential health impacts of air quality management programmes.

Difference in the relation between daily mortality and air pollution among elderly and all-ages populations in southwestern France

Numerous time series studies around the world have reported an association between mortality and particulate air pollution. We investigated the distribution over time of effect of air pollution on short-term mortality among subjects aged 65 years and older and of all ages in Bordeaux, France. Statistical analysis was based on generalized additive models using either loess or penalized spline smoothing. Our study found a significant positive association between air pollution and all nonaccidental mortality and specific mortality in both group of population (all ages and elderly) with a greater effect among the elderly, particularly for respiratory mortality. For this case, we observed a greater effect according to distributed lag models (0-5 days) among the elderly, with an estimated increase of 9.2% in the daily number of deaths for 10 microg/m(3) of daily black smoke [95% CI, 3.4-15.3]. These results contribute to the efforts made to understand how air pollution promotes adverse health effects and to identify susceptible subgroups.

Effect of diesel exhaust particulate (DEP) on immune responses: contributions of particulate versus organic soluble components

The effect of diesel exhaust particulate (DEP) exposure on innate, cellular and humoral pulmonary immunity was studied using high-dose, acute-exposure rat, mouse, and cell culture models. DEP consists of a complex mixture of petrochemical-derived organics adsorbed onto elemental carbon particles. DEP is a major component of particulate urban air pollution and a health concern in both urban and occupational environments. The alveolar macrophage is considered a key cellular component in pulmonary innate immunity. DEP and DEP organic extracts have been found to suppress alveolar macrophage function as demonstrated by reduced production of cytokines (interleukin-1 [IL-1], tumor necrosis factor- alpha [TNF- alpha]) and reactive oxygen species (ROS) in response to a variety of agents, including lipopolysaccharide (LPS), interferon- gamma (IFN- gamma), and bacteria. Fractionation of DEP organic extract suggests that this activity was predominately in polyaromatic-containing and more polar (resin) fractions. Organic-stripped DEP did not alter these innate pulmonary immune responses. DEP also depressed pulmonary clearance of Listeria monocytogenes and Bacillus Calmette-Guerin (BCG). The contribution of the organic component of DEP is less well defined with respect to acquired and humoral immunity. Indeed, both DEP and carbon black enhanced humoral immune responses (specific immunoglobulin [Ig] E and IgG) in an ovalbumin-sensitized rat model. It is concluded that both the particulate and adsorbed organics may contribute to DEP-mediated immune alterations.

Why cardiologists should be interested in air pollution

Despite major improvements in air quality resulting from increasingly stringent legislation, there remains a strong association between daily mortality and current levels of air pollution. Growing epidemiological evidence suggests that many, perhaps the majority, of these deaths are caused by cardiovascular disease.

Air Pollution and Myocardial Infarction in Rome

BACKGROUND

Daily air pollution is associated with increased hospital admissions for cardiovascular diseases, but there are few observations on the link with acute myocardial infarction. To evaluate the relation between various urban air pollutants (total suspended particulate, SO2, CO, NO2) and hospital admissions for acute myocardial infarction in Rome, Italy, we performed a case-crossover analysis and studied whether individual characteristics act as effect modifiers.

METHODS

We studied 6531 subjects residing in Rome and hospitalized for a first episode of acute myocardial infarction (International Classification of Diseases, 9th edition: 410) from January 1995 to June 1997. The following individual information was available: sex, age, date of hospitalization, coexisting illnesses (hypertension, 25%; diabetes, 15%), and cardiac severity (conduction disorders, 6%; cardiac dysrhythmias, 20%; heart failure, 11%). Daily air pollution data were taken from 5 city monitors. We used a time-stratified case-crossover design; control days were the same day of the week as the myocardial infarction occurred, in other weeks of the month.

RESULTS

Positive associations were found for total suspended particulate, NO2 and CO. The strongest and most consistent effect was found for total suspended particulate. The odds ratio (OR) associated with 10 micro g/m3 of total suspended particulate over the 0- to 2-day lag was 1.028 (95% confidence interval [CI] = 1.005-1.052). The association with total suspended particulate tended to be stronger among people older than 74 years of age (OR = 1.046; CI = 1.005-1.089), in the warm period of the year (OR = 1.046; CI = 1.008-1.087), and among subjects who had heart conduction disorders (OR = 1.080; CI = 0.987-1.181).

CONCLUSIONS

The results suggest that air pollution increases the risk of myocardial infarction, especially during the warm season. There was a tendency for a stronger effect among the elderly and people with heart conduction disturbances.

Lunar phases are not related to the occurrence of acute myocardial infarction and sudden cardiac death

BACKGROUND

Mass media deliver pertinacious rumours that lunar phases influence the progress and long-term results in several medical procedures. Peer reviewed studies support this, e.g. in myocardial infarction, others do not.

METHODS

We looked retrospectively at the dates of cardiac arrests (CA; n=368) of cardiac origin and of acute myocardial infarctions (AMI) with consecutive thrombolytic therapy or acute PTCA (n=872) and at the lunar phases at the corresponding dates. Medical data had been collected prospectively on the patient's admission. The lunar phases were defined as full moon+/-1 day, new moon+/-1 day and the days in between as waning and waxing moon. The incidence of these cardiac events at each phase was calculated as days with a case divided by the total number of days of the specific moon phase in the observation period (1992-1998). Wilcoxon Rank Test was used for statistical analysis.

RESULTS

AMI and CA occurred on equal percentages of days within each lunar phase: AMI on 35% of all days with new moon, on 38% of full moon days, on 39% waning, and on 41% of the waxing moon days; CA on 19, 17, 16 and 16% of all days of the respective lunar phase. This difference was not significant.

CONCLUSION

Lunar phases do not appear to correlate with acute coronary events leading to myocardial infarction or sudden cardiac death.

Health effects and time course of particulate matter on the cardiopulmonary system in rats with lung inflammation

Recent epidemiological studies associate health effects and particulate matter in ambient air. Exacerbation of the particle-induced inflammation can be a mechanism responsible for increased hospitalization and death due to cardiopulmonary events in high-risk groups of the population. Systems regulating blood pressure that depend on lung integrity can be involved in progression of cardiovascular diseases. This study focused on the expression levels of various genes involved in cardiovascular and pulmonary diseases to assess their role in the onset of cardiovascular problems due to ambient particulate matter and compared these with the corresponding products. Rats with ozone-induced (1600 microg/m(3); 8 h) pulmonary inflammation were exposed to 0.5 mg, 1.5 mg, or 5 mg of particulate matter (PM) from Ottawa Canada (EHC-93) by intratracheal instillation. mRNA levels of various genes and their products were measured 2, 4, and 7 d after instillation. At 2 d after exposures to PM, tumor necrosis factor (TNF)-alpha levels in bronchoalveolar lavage fluid (BALF) were elevated approximately 4 times for the highest EHC-93 dose. MIP-2 protein levels in BALF were elevated approximately three times during the entire time period studied, whereas IL-6 levels were not affected compared to control groups. The MIP-2 mRNA levels revealed a similar pattern of induction. A twofold increase in endothelin (ET)-1 levels at d 2 and a 20% decrease in angiotensin-converting enzyme (ACE) activity at d 7 were measured in plasma. A 60% decrease of ACE and ET-1 mRNA levels suggested a possible endothelial damage in the lung blood vessels. Inducible nitric oxide synthase (iNOS) mRNA was found to be increased 3.5 times 2 d after instillation of the particles. Therefore, the endothelial damage could have been caused by large amounts of the free radical NO. Also, plasma levels of fibrinogen were elevated (20%), which could presumably increase blood viscosity, leading to decreased tissue blood flow. These changes in hematological and hemodynamic parameters observed in our study are in line with heart failure in high-risk groups of the population after high air pollution episodes.

The temporal pattern of mortality responses to air pollution: a multicity assessment of mortality displacement

Although the association between particulate matter and mortality or morbidity is generally accepted, controversy remains about the importance of the association. If it is due solely to the deaths of frail individuals, which are brought forward by only a brief period of time, the public health implications of the association are fewer than if there is an increase in the number of deaths. Recently, other research has addressed the mortality displacement issue in single-city analysis. We analyzed this issue with a distributed lag model in a multicity hierarchic modeling approach, within the Air Pollution and Health: A European Approach (APHEA-2) study. We fit a Poisson regression model and a polynomial distributed lag model with up to 40 days of delay in each city. In the second stage we combined the city-specific results. We found that the overall effect of particulate matter less than 10 microM in aerodynamic diameter (PM10) per 10 microg/m3 for the fourth-degree distributed lag model is a 1.61% increase in daily deaths (95% CI = 1.02-2.20), whereas the mean of PM10 on the same day and the previous day is associated with only a 0.70% increase in deaths (95% CI = 0.43-0.97). This result is unchanged using an unconstrained distributed lag model. Our study confirms that the effects observed in daily time-series studies are not due primarily to short-term mortality displacement. The effect size estimate for airborne particles more than doubles when we consider longer-term effects, which has important implications for risk assessment.

The lag structure between particulate air pollution and respiratory and cardiovascular deaths in 10 US cities

To assess differences in the lag structure pattern between particulate matter < 10 microns/100 microns in diameter (PM10) and cause-specific mortality, we performed a time-series analysis in 10 US cities using generalized additive Poisson regressions in each city; nonparametric smooth functions were used to control for long time trend, weather, and day of the week. The PM10 effect was estimated based on its daily mean, 2-day moving average, and the cumulative 7-day effect by means of an unconstrained distributed lag model. A 10-microgram/m3 increase in the 7-day mean of PM10 was associated with increases in deaths due to pneumonia (2.7%, 95% confidence interval [CI]: 1.5, 3.9), chronic obstructive pulmonary disease (1.7%, 95% CI: 0.1, 3.3), and all cardiovascular diseases (1.0%, 95% CI: 0.6, 1.4). A 10-microgram/m3 increase in the 2-day mean of PM10 was associated with a 0.7% (95% CI: 0.3, 1.1) increase in deaths from myocardial infarction. When the distributed lag was assessed, two different patterns could be observed: respiratory deaths were more affected by air pollution levels on the previous days, whereas cardiovascular deaths were more affected by same-day pollution. These results contribute to the overall efforts so far in understanding how exposure to air pollution promotes adverse health effects.

The association between air pollution and heart failure, arrhythmia, embolism, thrombosis, and other cardiovascular causes of death in a time series study

In a time series study, air pollution was associated with specific cardiovascular causes of death. Deaths due to heart failure (ICD-9 428), arrhythmia (ICD-9 427), cerebrovascular causes (ICD-9 430-436), and thrombocytic causes (ICD-9 415.1, 433-4, 444, 452-3) were more strongly associated with air pollution than cardiovascular deaths (ICD-9 390-448) in general. Excess relative risks were 2.5 to 4 times larger for these categories than for total cardiovascular disease mortality. Heart failure deaths, which made up 10% of all cardiovascular deaths, were found to be responsible for about 30% of the cardiovascular deaths related to particulate matter, SO2, CO, and NO2.

The distributed lag between air pollution and daily deaths

Many studies have reported associations between air pollution and daily deaths. Those studies have not consistently specified the lag between exposure and response, although most have found associations that persisted for more than 1 day. A systematic approach to specifying the lag association would allow better comparison across sites and give insight into the nature of the relation. To examine this question, I fit unconstrained and constrained distributed lag relations to the association between daily deaths of persons 65 years of age and older with PM10 in 10 U.S. cities (New Haven, Birmingham, Pittsburgh, Canton, Detroit, Chicago, Minneapolis, Colorado Springs, Spokane, and Seattle) that had daily monitoring for PM10. After control for temperature, humidity, barometric pressure, day of the week, and seasonal patterns, I found evidence in each city that the effect of a single day's exposure to PM10 was manifested across several days. Averaging over the 10 cities, the overall effect of an increase in exposure of 10 microg/m3 on a single day was a 1.4% increase in deaths (95% confidence intervals (CI) = 1.15-1.68) using a quadratic distributed lag model, and a 1.3% increase (95% CI = 1.04-1.56) using an unconstrained distributed lag model. In contrast, constraining the model to assume the effect all occurs in one day resulted in an estimate of only 0.65% (95% CI = 0.49-0.81), indicating that this constraint leads to a substantial underestimate of effect. Combining the estimated effect at each day's lag across the 10 cities showed that the effect was spread over several days and did not reach zero until 5 days after the exposure. Given the distribution of sensitivities likely in the general population, this result is biologically plausible. I also found a protective effect of barometric pressure in all 10 locations.

Race, gender, and social status as modifiers of the effects of PM10 on mortality

Interest has recently been focused on which populations are most at risk of premature mortality induced by air pollution. This coincides with greater concern about environmental justice. We analyzed total mortality in the four largest US cities with daily measurements of particulate matter less than 10 microns (PM10) and combined the results to determine whether race, sex, and education are potential modifiers of the effects of PM10 on mortality. We computed daily counts of deaths stratified by sex, race, and education in each city and investigated their associations with PM10 in a Poisson regression model. We combined the results by using inverse variance weighted averages. We found evidence of effect modification by sex, with the slope in female deaths one third larger than in male deaths, whereas for social factors and race we found only weak evidence of effect modification. In general, the effect modification appeared modest compared with other reports of substantial effect modification by medical conditions.