Concentrated ambient air particles induce mild pulmonary inflammation in healthy human volunteers

Exposure to concentrated ambient air particles alters hematologic indices in humans

Descriptions of changes in hematological indices have contested the premise that the biological effects of suspended particulate matter (PM) are restricted to the lung. Employing approximately 40 hematologic parameters reflecting blood cells, chemistries, mediators, and coagulation factors, we tested the hypothesis that exposure to concentrated ambient air particles (CAPs) can be associated with changes in hematologic indices in normal humans. Twenty healthy young volunteers were exposed to either filtered air (n = 5) or CAPs (n = 15) with a mean PM mass of 120.5 +/- 14.0 microg/m3 and a range from 15.0-357.6 microg/m3. Hematologic indices were measured. Changes in all parameters are expressed as the absolute value either immediately after or 24 h after exposure. Differences between responses of those individuals exposed to filtered air and CAPs were tested using the T-test of independent means. If significant differences between the two groups were suggested by the T-test (p < .10), the relationship was further evaluated employing linear regression techniques. Regression analysis verified significant linear relationships between particle mass the individual was exposed to and (1) decrements in WBC count 24 h later, (2) decreases in lactate dehydrogenase (LDH) concentration 24 h later, and (3) elevations in fibrinogen levels 24 h later. There were no changes in either inflammatory mediators in the blood or indices of coagulation/fibrinolysis other than fibrinogen. We conclude that exposure of healthy volunteers to CAPs can be associated with decreases of both white blood cell (WBC) count and LDH and increased concentrations of fibrinogen in the blood.

[Air pollution and cardiovascular toxicity: known risks]

SUBJECT

Review of studies about epidemiological and physiopathological knowledge of ambient air particles short-term cardio-vascular effects. CURRENTS AND STRONG POINTS: Many studies, in contrasted countries for pollution's sources, meteorological conditions or socio-demographical characteristics, have shown health effects due to ambient air particles. After having studied mainly the respiratory effects of particulate air pollution, epidemiologists are now interested in the cardio-vascular effects of ambient air particles. In fact, serious effects seem to exist in fragile people which can get to emergency department visits, hospitalisation and even death. In addition, studies have shown less serious effects, but likely to be frequent (cardiac symptoms, and stoppages for cardio-vascular causes, notably). The exact mechanism by which particles have cardio-vascular adverse health effects is unknown, but experimental and epidemiological studies have led to several hypotheses: local pulmonary effects seem to be followed by systemic effects, which would be responsible for effects on the electrical activity of the heart through cardiac autonomic dysfunction and effects on the blood supply to the heart. The objective of this work is to summarise epidemiological and physiopathological knowledge about the cardio-vascular effects of ambient air particles.

PROSPECTS AND PROJECTS

To evaluate the real importance of cardio-vascular effects due to particulate air pollution and to identify their exact mechanism, a more precise knowledge of detailed causes of deaths and hospitalisations and a better knowledge of less serious effects, but likely to be frequent, is necessary. Equally, a detailed identification of fragile people is essential for developing preventive actions.

Characterization of a hooded human exposure apparatus for inhalation of gases and aerosols

A human exposure apparatus was designed to administer a gas and/or aerosol directly to the subject's face. This apparatus utilized a hood associated with a powered air-purifying respirator. The design criteria included the need to maximize subject comfort, maintain consistent atmospheres of a gas or dust within the hood, and the accurate use of direct-reading instruments to monitor exposure levels. An 83-L drum was used to pre-mix the gas or aerosol with the main dilution air prior to entering the hood worn by the subject. A clear plastic oxygen tent, ventilated with room exhaust air, was used to contain contaminants exiting the hood. Bypass valves were added to allow for a startup period during which contaminant concentration levels were allowed to stabilize prior to exposing the human subject. Results from characterization studies demonstrated that the system adequately contained contaminants within the oxygen tent, provided adequate mixing of contaminant and dilution air, produced stable contaminant concentrations over time, and was responsive to sudden changes in contaminant generation rate.

Particulate matter exposure in cars is associated with cardiovascular effects in healthy young men

Exposure to fine airborne particulate matter (PM(2.5)) is associated with cardiovascular events and mortality in older and cardiac patients. Potential physiologic effects of in-vehicle, roadside, and ambient PM(2.5) were investigated in young, healthy, nonsmoking, male North Carolina Highway Patrol troopers. Nine troopers (age 23 to 30) were monitored on 4 successive days while working a 3 P.M. to midnight shift. Each patrol car was equipped with air-quality monitors. Blood was drawn 14 hours after each shift, and ambulatory monitors recorded the electrocardiogram throughout the shift and until the next morning. Data were analyzed using mixed models. In-vehicle PM(2.5) (average of 24 microg/m(3)) was associated with decreased lymphocytes (-11% per 10 microg/m(3)) and increased red blood cell indices (1% mean corpuscular volume), neutrophils (6%), C-reactive protein (32%), von Willebrand factor (12%), next-morning heart beat cycle length (6%), next-morning heart rate variability parameters, and ectopic beats throughout the recording (20%). Controlling for potential confounders had little impact on the effect estimates. The associations of these health endpoints with ambient and roadside PM(2.5) were smaller and less significant. The observations in these healthy young men suggest that in-vehicle exposure to PM(2.5) may cause pathophysiologic changes that involve inflammation, coagulation, and cardiac rhythm.

Pulmonary and systemic effects of short-term inhalation exposure to ultrafine carbon black particles

While environmental particles are associated with mortality and morbidity related to pulmonary and cardiovascular (CV) disease, the mechanisms involved in CV health effects are not known. Changes in systemic clotting factors have been associated with pulmonary inflammation. We hypothesized that inhaled ultrafine particles result in an inflammatory response which may stimulate systemic clotting factor release. Adult male Wistar rats were exposed to either fine or ultrafine carbon black (CB) for 7 h. The attained total suspended particle concentrations were 1.66 mg/m(3) for ultrafine CB and 1.40 mg/m(3) for fine CB. Particle concentration of ultrafine particles was more than 10 times greater than that of fine particles and the count median aerodynamic diameter averaged 114 nm for the ultrafine and 268 nm for the fine carbon particles. Data were collected immediately, 16 and 48 h following exposure. Only ultrafine CB caused an increase in total bronchoalveolar lavage (BAL) leukocytes, whereas both fine (2-fold) and ultrafine (4-fold) carbon particles caused an increase in BAL neutrophils at 16 h postexposure. Exposure to the ultrafine, but not fine, carbon was also associated with significant increases in the total numbers of blood leukocytes. Plasma fibrinogen, factor VII and von Willebrand factor (vWF) were unaffected by particle treatments as was plasma Trolox equivalent antioxidant status (TEAC). Macrophage inflammatory protein-2 mRNA was significantly increased in BAL cells 48 h following exposure to ultrafine CB. The data show that there is a small but consistent significant proinflammatory effect of this exposure to ultrafine particles that is greater than the effect of the same exposure to fine CB.

Oxidant mechanisms in response to ambient air particles

The toxic effects of air pollution are widely documented. In recent years, however, there has been an increasing interest in the study of the health effects of particulate matter (PM), a previously unexplored constituent of urban air pollution. Exposure to increased levels of PM of respirable size is strongly and consistently associated with increased cardiopulmonary morbidity and mortality. Conversely, improved air quality appears to correlate with decreased mortality. Particulate matter is a mixture of inorganic and organic components that vary in size, origin, and composition. The mechanisms of PM health effects are still poorly understood. However, studies in cellular and animal models suggest a variety of possible mechanisms including direct effects of particle components on the intracellular sources of reactive oxygen species (ROS), indirect effects due to pro-inflammatory mediators released from PM-stimulated macrophages, and neural stimulation after particle deposition in the lungs. The involvement of ROS in each one of these possible pathways is discussed.

Reactive oxygen species in pulmonary inflammation by ambient particulates

Exposure to ambient air pollution particles (PM) has been associated with increased cardiopulmonary morbidity and mortality, particularly in individuals with pre-existing disease. Exacerbation of pulmonary inflammation in susceptible people (e.g., asthmatics, COPD patients) appears to be a central mechanism by which PM exert their toxicity. Health effects are seen most consistently with PM with aerodynamic diameter < 2.5 micrometers (PM(2.5)), although 10 micrometers < PM < 2.5 micrometers can also be toxic. Through its metal, semi-quinone, lipopolysaccaride, hydrocarbon, and ultrafine constituents, PM may exert oxidative stress on cells in the lung by presenting or by stimulating the cells to produce reactive oxygen (ROS). In vivo, PM increase cytokine and chemokine release, lung injury, and neutrophil influx. In vitro analysis of PM effects on the critical cellular targets, alveolar macrophages, epithelial cells, and neutrophils, demonstrates PM- and oxidant-dependent responses consistent with in vivo data. These effects have been observed with PM samples collected over years as well as concentrated PM(2.5) (CAPs) collected in real time. Oxidative stress mediated by ROS is an important mechanism of PM-induced lung inflammation.

Persistent hyperreactivity and reactive airway dysfunction in firefighters at the World Trade Center

New York City Fire Department rescue workers experienced massive exposure to airborne particulates at the World Trade Center site. Aims of this longitudinal study were to (1) determine if bronchial hyperreactivity was present, persistent, and independently associated with exposure intensity, (2) identify objective measures shortly after the collapse that would predict persistent hyperreactivity and a diagnosis of reactive airways dysfunction 6 months post-collapse. A representative sample of 179 rescue workers stratified by exposure intensity (high, moderate, and control) without current smoking or prior respiratory disease was enrolled. Highly exposed workers arrived within 2 hours of collapse, moderately exposed workers arrived later on Days 1-2; control subjects were not exposed. Hyperreactivity at 1, 3, and 6 months post-collapse was associated with exposure intensity, independent of ex-smoking and airflow obstruction. Six months post-collapse, highly exposed workers were 6.8 times more likely than moderately exposed workers and control subjects to be hyperreactive (95% confidence interval, 1.8-25.2; p = 0.004), and hyperreactivity persisted in 55% of those hyperreactive at 1 and/or 3 months. In highly exposed subjects, hyperreactivity 1 or 3 months post-collapse was the sole predictor for reactive airways dysfunction (p = 0.021). In conclusion, development and persistence of hyperreactivity and reactive airways dysfunction were strongly and independently associated with exposure intensity. Hyperreactivity shortly post-collapse predicted reactive airways dysfunction at 6 months in highly exposed workers; this has important implications for disaster management.

Oxidative stress and calcium signaling in the adverse effects of environmental particles (PM10)

This review focuses on the potential role that oxidative stress plays in the adverse effects of PM(10). The central hypothesis is that the ability of PM(10) to cause oxidative stress underlies the association between increased exposure to PM(10) and both exacerbations of lung disease and lung cancer. Pulmonary inflammation may also underlie the cardiovascular effects seen following increased PM(10), although the mechanisms of the cardiovascular effects of PM(10) are not well understood. PM(10) is a complex mix of various particle types and several of the components of PM(10) are likely to be involved in the induction of oxidative stress. The most likely of these are transition metals, ultrafine particle surfaces, and organic compounds. In support of this hypothesis, oxidative stress arising from PM(10) has been shown to activate a number of redox-responsive signaling pathways in lung target cells. These pathways are involved in expression of genes that play a role in responses relevant to inflammation and pathological change, including MAPKs, NF-kappaB, AP-1, and histone acetylation. Oxidative stress from particles is also likely to play an important role in the carcinogenic effects associated with PM(10) and hydroxyl radicals from PM(10) cause DNA damage in vitro.

Contribution of respiratory disease to nonrespiratory mortality associations with air pollution

Many time series studies have found that individuals with primary cardiac conditions were susceptible to the adverse effects associated with increased ambient particle levels. However, the mechanism(s) of these associations is not yet understood. In this study, we evaluate whether individuals with nonrespiratory primary causes of death who also had contributing respiratory causes listed on their death certificates were more affected by air pollution, as compared with those not having contributing respiratory conditions. Short-term associations between ambient particulate matter (10 microm or less in aerodynamic diameter) and mortality were modeled in New York City for the years 1985-1994. It was observed that among those 75 years or more, those with contributing respiratory disease had higher relative risks (95% confidence intervals) calculated per interquartile range, as compared with those without contributing respiratory disease for both circulatory deaths (relative risk = 1.066 [1.027-1.106] versus 1.022 [1.008-1.035]) and cancer deaths (relative risk = 1.129 [1.041-1.225] versus 1.025 [1.000-1.050]). However, this pattern of association was not observed for those who were less than 75 years old. The results of this study suggest that past studies may have underestimated the role of respiratory disease in pollution-mortality associations, especially among older adults.

Personal PM2.5 exposure and markers of oxidative stress in blood

Ambient particulate air pollution assessed as outdoor concentrations of particulate matter less than or equal to 2.5 micro m in diameter (PM(2.5)) in urban background has been associated with cardiovascular diseases at the population level. However, the significance of individual exposure and the involved mechanisms remain uncertain. We measured personal PM(2.5) and carbon black exposure in 50 students four times in 1 year and analyzed blood samples for markers of protein and lipid oxidation, for red blood cell (RBC) and platelet counts, and for concentrations of hemoglobin and fibrinogen. We analyzed protein oxidation in terms of gamma-glutamyl semialdehyde in hemoglobin (HBGGS) and 2-aminoadipic semialdehyde in hemoglobin (HBAAS) and plasma proteins (PLAAS), and lipid peroxidation was measured as malondialdehyde (MDA) in plasma. Median exposures were 16.1 micro g/m(3) for personal PM(2.5) exposure, 9.2 micro g/m(3) for background PM(2.5) concentration, and 8.1 X 10(-6)/m for personal carbon black exposure. Personal carbon black exposure and PLAAS concentration were positively associated (p < 0.01), whereas an association between personal PM(2.5) exposure and PLAAS was only of borderline significance (p = 0.061). A 3.7% increase in MDA concentrations per 10 micro g/m(3) increase in personal PM(2.5) exposure was found for women (p < 0.05), whereas there was no significant relationship for the men. Similarly, positive associations between personal PM(2.5)exposure and both RBC and hemoglobin concentrations were found only in women (p < 0.01). There were no significant relationships between background PM(2.5) concentration and any of the biomarkers. This suggests that exposure to particles in moderate concentrations can induce oxidative stress and increase RBCs in peripheral blood. Personal exposure appears more closely related to these biomarkers potentially related to cardiovascular disease than is ambient PM(2.5) background concentrations.

Air pollution: the "Heart" of the problem

Air pollution exposure is associated with an increased risk of acute and chronic cardiovascular mortality. Recent observations have implicated fine particulate matter (PM(2.5)) as one of the most important pollutants. Inhalation of PM(2.5) causes acute pulmonary inflammation and oxidative stress. The subsequent generation of a systemic inflammatory response could link air pollution exposure with the development of cardiovascular disease. Human experiments have demonstrated pro-arrhythmic alterations in cardiac autonomic tone, increased blood pressure, higher serum C-reactive protein levels, and alterations in blood rheology favoring coagulation following controlled pollution exposures or in relation to elevated ambient PM(2.5) levels. Recent studies have also uncovered several harmful impacts on the systemic vasculature, including the triggering of acute vasoconstriction and the enhanced development of atherosclerosis. Many questions, however, remain unanswered and future studies will be required to clarify the relevant biologic mechanisms and to identify the specific constituents responsible for mediating the adverse health impacts.

Generation of a monoclonal antibody that blocks epithelial binding of unopsonized particles

Alveolar macrophages (AMs) and epithelial cells (ECs) are the first cells in the lung to encounter inhaled environmental particles. The initial interaction between AMs and particles is mediated by specific scavenger receptors, but the nature of the structure(s) on ECs that also bind particles has not been well-described. To characterize the nature of the EC particle receptor, we screened a panel of mouse anti-human EC hybridomas for functional blockade of EC particle binding. This strategy identified a monoclonal antibody (MAb) (EPR1) that blocks binding of titanium dioxide (TiO(2)) particles to the EC line which served as the immunogen (A549), as well as to other EC lines (Beas 2-B, HTB54, HeLa, and MDA-MB-435S). EPR1 demonstrated specific labeling of ECs using immunohistology techniques and its expression could be quantitated by flow cytometry of permeabilized ECs in suspension. MAbs such as EPR1 may prove useful in further analysis of receptors for inhaled particles on lung epithelial cells.

Mitochondrial oxidant production by a pollutant dust and NO-mediated apoptosis in human alveolar macrophage

Residual oil fly ash (ROFA) is a pollutant dust that stimulates production of reactive oxygen species (ROS) from mitochondria and apoptosis in alveolar macrophages (AM), but the relationship between these two processes is unclear. In this study, human AM were incubated with ROFA or vanadyl sulfate (VOSO(4)), the major metal constituent in ROFA, with or without nitro-L-arginine methyl ester (L-NAME), diphenyleneiodonium (DPI), and mitochondrial electron transport inhibitors. Interactions among production of ROS, nitric oxide (NO), and apoptosis of AM were determined. ROFA-stimulated ROS production was attenuated by DPI, rotenone, antimycin, and NaN(3), but not by L-NAME, a pattern mimicked by VOSO(4). ROFA-induced apoptosis was inhibited by L-NAME and a caspase-3-like protease inhibitor, but not by mitochondrial inhibitors. ROFA enhanced NO-mediated increase in caspase-3-like activity. VOSO(4) had minor effects on apoptosis. Thus ROFA-stimulated production of ROS from mitochondria was independent of apoptosis of AM, which was mediated by activation of caspase-3-like proteases and NO. The pro-oxidant effect but not the proapoptotic effect of ROFA was mediated by vanadium.

Relación a corto plazo de la contaminación atmosférica y la mortalidad en 13 ciudades españolas

BACKGROUND AND OBJECTIVE

EMECAM is a collaborative project that seeks to evaluate the short-term effects of air pollution on mortality in Spain.

MATERIAL AND METHOD

We collected data for air pollutants (particles and gases), daily mortality (total except external, cardiovascular and respiratory causes) and co-variables (temperature, humidity, influenza and calendar variables) in 13 Spanish cities. The magnitude of the association in every city was estimated using GAM under a Poisson distribution. Combined estimates for each cause and pollutant were obtained under 'fixed effects' and 'random effects'models.

RESULTS

An increase of 10 (g/m3 in the levels of the average of the concurrent and one day lag for black smoke was associated with a 0.8% (CI: 0.4-1.1) increase in mortality. The same increase in the concentration of SO2 was associated with a 0.5% (CI: 0.1-1.0) increase in daily deaths, and a 0.6% (CI: 0.3-0.8) increase in the case of NO2. An increase of 1 mg/m3 in the levels of CO was associated with an increase of 1.5% (CI: 0.5-2.6) in daily deaths.

CONCLUSIONS

There is a short-term association between increases of daily levels of air pollutants and the number of daily deaths in Spanish cities.

Size effect of intratracheally instilled particles on pulmonary inflammation and vascular thrombosis

Particulate air pollution is associated with cardiorespiratory effects and ultrafine particles (UFPs, diameter < 100 nm) are believed to play an important role. We studied the acute (1 h) effect of intratracheally instilled unmodified (60 nm), negatively charged carboxylate-modified (60 nm), or positively charged amine-modified (60 or 400 nm) polystyrene particles on bronchoalveolar lavage (BAL) indices and on peripheral thrombosis in hamster. The latter was assessed by measuring the extent of photochemically induced thrombosis in a femoral vein via transillumination. Unmodified and negative UFPs did not modify thrombosis and BAL indices. Positive UFPs increased thrombosis at 500 microg per animal (+ 341 +/- 96%) and at 50 microg per animal (+ 533 +/- 122%), but not at 5 microg per animal. Neutrophils, lactate dehydrogenase, and histamine were increased in BAL at all these doses but protein concentration was increased only at 500 microg per animal. Positive 400-nm particles (500 microg per animal) did not affect thrombosis, although they led to a neutrophil influx and an increase in BAL proteins and histamine. Using the Platelet Function Analyser (PFA-100), the platelets of hamsters were activated by the in vitro addition of positive UFPs and 400-nm particles to blood. We conclude that intratracheally administered positive ultrafine and 400-nm particles induce pulmonary inflammation within 1 h. Positive UFPs, but not the 400-nm particles enhance thrombosis. Hence, particle-induced lung inflammation and thrombogenesis can be partially uncoupled.

Update on the health effects of outdoor air pollution

The number of studies conducted on the health effects of air pollution has increased exponentially. Important methodological advances include the application of novel observational study designs, in particular the multi-city design, and the development and application of airborne particle concentrators for use in experimental human exposure studies and toxicological studies. Experimental data are validating and providing insight into some surprising observational findings.

Hematological changes of children exposed to volatile organic compounds containing low levels of benzene

We conducted a cohort study to evaluate the hematological changes of children environmentally exposed to volatile organic compounds (VOCs). The study subjects comprised 192 children who consisted of 97 children living near a petrochemical estate region and 95 children living in a suburban region of Ulsan, Korea. We executed the hematological examination three times, in April, July and October. A generalized linear model analysis was used to test for changes over time in the complete blood count (CBC) values of each study group. All CBC values of children showed differences between regions in accordance with the survey month. In the model, region was a significant independent variable for the total white blood cell, red blood cell, and platelet. This suggests that the amounts of exposure to VOCs are different between study groups in different months, and environmental exposure to VOCs is associated with a higher prevalence of hematological abnormalities. Hematological abnormalities in children exposed to VOCs containing low levels of benzene could serve as a biological marker of atmospheric VOCs.

[Particulate air pollution and health in Valencia [Spain] 1994-1996]

OBJECTIVE

To estimate the short-term association between levels of air pollution due to suspended particulates and several indicators of morbidity and mortality in the city of Valencia, Spain.

METHODS

We performed an ecological time-series study. Daily levels of air pollution from black smoke were related to indicators of mortality, hospital admissions, and visits to emergency departments in the city of Valencia between 1994 and 1996. The magnitude of the association was estimated through Poisson autoregression using generalized additive models. The form of the relationship, the delayed effect of pollution, and the possible modification of this effect by other pollutants or periods of the year were assessed.

RESULTS

A significant association was found between levels of suspended particulates and several of the indicators analyzed in Valencia. The form of this relationship was linear. An increment of 10 microg/m3 in the daily levels of black smoke was associated with an increase of 1.8% (95% confidence interval: 0.9-2.7%) in the number of deaths on the following day. The same increment in pollutant levels was associated with an increase of 1.5% (0.1-2.8%) in deaths from all cardiovascular causes, an increase of 1.3% (0.0-2.6%) in admissions for all cardiovascular diseases and in an increase of 5.4% (0.6-10.4%) in the number of emergency visits for asthma. This association was not confounded by levels of other pollutants. Black smoke was not associated with mortality from respiratory diseases, with hospital admissions for cerebrovascular diseases, or with emergency visits for chronic obstructive pulmonary disease.

CONCLUSIONS

This study provides evidence that levels of suspended particles in Valencia are associated with emergency visits for asthma, hospital admissions for cardiovascular diseases, and daily deaths. The association found is consistent with the results of previous studies and fits with recent knowledge of psychopathological mechanisms.

Temporal association between pulmonary and systemic effects of particulate matter in healthy and cardiovascular compromised rats

Exposure to particulate matter (PM) has been associated with increased morbidity and mortality among individuals with cardiovascular disease. It is hypothesized that systemic alterations occur concurrent to pulmonary injury/inflammation, and contribute to cardiac events in compromised hosts. We explored this hypothesis using a rat model for human hypertension and cardiovascular disease (spontaneously hypertensive, SH), and normotensive Wistar Kyoto (WKY) rats. SH and WKY rats (12-13 wk old) were exposed either intratracheally (IT; 0.0, 1.0, or 5.0 mg/kg in saline) or nose-only (15 mg/m(3) x 6 h/d x 3 d/wk x 1, 2 or 4 wk) to combustion source residual oil fly ash (ROFA) with low metal content, and examined 1, 2 or 4 d later. Bronchoalveolar lavage fluid (BALF) albumin and neutrophils increased (SH approximately equal WKY) at d 1 following ROFA IT. With inhalation exposure, both strains experienced progressive histological lung damage and increases in BALF albumin and neutrophils during 1 to 4 wk (SH > WKY). Acute lung injury from ROFA IT was temporally associated with increases in plasma fibrinogen in both strains, but only the SH rats responded to the acute 1-wk ROFA inhalation. Longer term (2 or 4 wk) ROFA caused progressive lung injury (SH > WKY), but did not sustain the increase in fibrinogen. BALF glutathione increased in a temporal fashion similar to fibrinogen; however, only WKY rats demonstrated this response. There was a small but consistent decrease in blood lymphocytes and an increase in blood neutrophils in SH rats exposed to ROFA acutely. In conclusion, acute PM exposure can provoke an acute systemic thrombogenic response associated with pulmonary injury/inflammation and oxidative stress in cardiovascular compromised rats. This evidence is consistent with greater cardiovascular events during acute PM episodes in compromised humans.

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

STUDY OBJECTIVE

As part of the APHEA project this study examined the association between airborne particles and hospital admissions for cardiac causes (ICD9 390-429) in eight European cities (Barcelona, Birmingham, London, Milan, the Netherlands, Paris, Rome, and Stockholm). All admissions were studied, as well as admissions stratified by age. The association for ischaemic heart disease (ICD9 410-413) and stroke (ICD9 430-438) was also studied, also stratified by age.

DESIGN

Autoregressive Poisson models were used that controlled for long term trend, season, influenza epidemics, and meteorology to assess the short-term effects of particles in each city. The study also examined confounding by other pollutants. City specific results were pooled in a second stage regression to obtain more stable estimates and examine the sources of heterogeneity.

MAIN RESULTS

The pooled percentage increases associated with a 10 micro g/m(3) increase in PM(10) and black smoke were respectively 0.5% (95% CI: 0.2 to 0.8) and 1.1% (95% CI: 0.4 to 1.8) for cardiac admissions of all ages, 0.7% (95% CI: 0.4 to 1.0) and 1.3% (95% CI: 0.4 to 2.2) for cardiac admissions over 65 years, and, 0.8% (95% CI: 0.3 to 1.2) and 1.1% (95% CI: 0.7 to 1.5) for ischaemic heart disease over 65 years. The effect of PM(10) was little changed by control for ozone or SO(2), but was substantially reduced (CO) or eliminated (NO(2)) by control for other traffic related pollutants. The effect of black smoke remained practically unchanged controlling for CO and only somewhat reduced controlling for NO(2).

CONCLUSIONS

These effects of particulate air pollution on cardiac admissions suggest the primary effect is likely to be mainly attributable to diesel exhaust. Results for ischaemic heart disease below 65 years and for stroke over 65 years were inconclusive.

Lung inflammation induced by concentrated ambient air particles is related to particle composition

The objectives of this study were (1) to determine whether short-term exposures to concentrated air particles (CAPs) cause pulmonary inflammation in normal rats and rats with chronic bronchitis (CB); (2) to identify the site within the lung parenchyma where CAPs-induced inflammation occurs; and (3) to characterize the component(s) of CAPs that is significantly associated with the development of the inflammatory reaction. Four groups of animals were studied: (1) air treated, filtered air exposed (air-sham); (2) sulfur dioxide treated (CB), filtered air exposed (CB-sham); (3) air treated, CAPs exposed (air-CAPs); and (4) sulfur dioxide treated, CAPs exposed (CB-CAPs). CB and normal rats were exposed by inhalation either to filtered air or CAPs during 3 consecutive days (5 hours/day). Pulmonary inflammation was assessed by bronchoalveolar lavage (BAL) and by measuring the numerical density of neutrophils (Nn) in the alveolar walls at the bronchoalveolar junction and in more peripheral alveoli. CAPs (as a binary exposure term) and CAPs mass (in regression correlations) induced a significant increase in BAL neutrophils and in normal and CB animals. Nn in the lung tissue significantly increased with CAPs in normal animals only. Greater Nn was observed in the central compared with peripheral regions of the lung. A significant dose-dependent association was found between many CAPs components and BAL neutrophils or lymphocytes, but only vanadium and bromine concentrations had significant associations with both BAL neutrophils and Nn in CAPs-exposed groups analyzed together. Results demonstrate that short-term exposures to CAPs from Boston induce a significant inflammatory reaction in rat lungs, with this reaction influenced by particle composition.

Air pollution and brain damage

Exposure to complex mixtures of air pollutants produces inflammation in the upper and lower respiratory tract. Because the nasal cavity is a common portal of entry, respiratory and olfactory epithelia are vulnerable targets for toxicological damage. This study has evaluated, by light and electron microscopy and immunohistochemical expression of nuclear factor-kappa beta (NF-kappaB) and inducible nitric oxide synthase (iNOS), the olfactory and respiratory nasal mucosae, olfactory bulb, and cortical and subcortical structures from 32 healthy mongrel canine residents in Southwest Metropolitan Mexico City (SWMMC), a highly polluted urban region. Findings were compared to those in 8 dogs from Tlaxcala, a less polluted, control city. In SWMMC dogs, expression of nuclear neuronal NF-kappaB and iNOS in cortical endothelial cells occurred at ages 2 and 4 weeks; subsequent damage included alterations of the blood-brain barrier (BBB), degenerating cortical neurons, apoptotic glial white matter cells, deposition of apolipoprotein E (apoE)-positive lipid droplets in smooth muscle cells and pericytes, nonneuritic plaques, and neurofibrillary tangles. Persistent pulmonary inflammation and deteriorating olfactory and respiratory barriers may play a role in the neuropathology observed in the brains of these highly exposed canines. Neurodegenerative disorders such as Alzheimer's may begin early in life with air pollutants playing a crucial role.

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.

Diffuse alveolar damage after exposure to an oil fly ash

Epidemiological investigation has established an association between exposure to particulate matter (PM) and both human mortality and diverse indices of human morbidity. However, attributing adverse health effects of specific individuals to PM exposure in these studies is not possible. Consequently, their clinical presentation remains ill-defined. We describe a 42-yr-old male with both respiratory damage, abnormal blood end points, and cardiac effects following an exposure to an emission source air pollution particle aerosolized during the cleaning of his domestic oil-burning stove. Early symptoms of shortness of breath and wheezing progressed over 2 wk to hypoxic respiratory failure necessitating mechanical ventilation. Blood indices were abnormal. Thoracoscopic biopsy demonstrated particle-laden macrophages and diffuse alveolar damage. Symptomatic and objective improvement rapidly followed initiation of corticosteroids. He developed typical anginal symptoms within 2 wk of discharge; however, coronary angiography did not identify any significant narrowing of the epicardial coronary arteries. This patient presents with the aggregate of potential injuries described by epidemiological methods to be associated with air pollution particle exposure.

Potential mechanisms of adverse pulmonary and cardiovascular effects of particulate air pollution (PM10)

PM10 is the international convention for measuring environmental particulate air pollution. Increases in PM10 have been linked to exacerbations of airways disease and deaths from respiratory and cardiovascular causes. PM10 is a complex and variable mixture but toxicological data suggests that ultrafine particles, transition metals and endotoxins are the most likely components to mediate adverse health effects. Potential mechanisms for the local and systemic adverse effects of PM10 are discussed.