Paradoxical ozone associations could be due to methyl nitrite from combustion of methyl ethers or esters in engine fuels

The Impact of Short-Term Outdoor Air Pollution on Clinical Status and Prognosis of Hospitalized Patients with Coronary Artery Disease Treated with Percutaneous Coronary Intervention

Background: The aim of this study was to determine the influence of acute exposure to air pollutants on patients’ profile, short- and mid-term outcomes of hospitalized patients with coronary artery disease (CAD) treated with coronary angioplasty. Methods: Out of 19,582 patients of the TERCET Registry, 7521 patients living in the Upper Silesia and Zaglebie Metropolis were included. The study population was divided into two groups according to the diagnosis of chronic (CCS) or acute coronary syndromes (ACS). Data on 24-h average concentrations of particulate matter with aerodynamic diameter <10 μm (PM10), sulfur dioxide (SO₂), nitrogen monoxide (NO), nitrogen dioxide (NO₂), and ozone (O₃) were obtained from eight environmental monitoring stations. Results: No significant association between pollutants’ concentration with baseline characteristic and in-hospital outcomes was observed. In the ACS group at 30 days, exceeding the 3rd quartile of PM10 was associated with almost 2-fold increased risk of adverse events and more than 3-fold increased risk of death. Exceeding the 3rd quartile of SO₂ was connected with more than 8-fold increased risk of death at 30 days. In the CCS group, exceeding the 3rd quartile of SO₂ was linked to almost 2,5-fold increased risk of 12-month death. Conclusions: The acute increase in air pollutants’ concentrations affect short- and mid-term prognosis in patients with CAD.

Weather elements, chemical air pollutants and airborne pollen influencing asthma emergency room visits in Szeged, Hungary: performance of two objective weather classifications

Weather classification approaches may be useful tools in modelling the occurrence of respiratory diseases. The aim of the study is to compare the performance of an objectively defined weather classification and the Spatial Synoptic Classification (SSC) in classifying emergency department (ED) visits for acute asthma depending from weather, air pollutants, and airborne pollen variables for Szeged, Hungary, for the 9-year period 1999-2007. The research is performed for three different pollen-related periods of the year and the annual data set. According to age and gender, nine patient categories, eight meteorological variables, seven chemical air pollutants, and two pollen categories were used. In general, partly dry and cold air and partly warm and humid air aggravate substantially the symptoms of asthmatics. Our major findings are consistent with this establishment. Namely, for the objectively defined weather types favourable conditions for asthma ER visits occur when an anticyclonic ridge weather situation happens with near extreme temperature and humidity parameters. Accordingly, the SSC weather types facilitate aggravating asthmatic conditions if warm or cool weather occur with high humidity in both cases. Favourable conditions for asthma attacks are confirmed in the extreme seasons when atmospheric stability contributes to enrichment of air pollutants. The total efficiency of the two classification approaches is similar in spite of the fact that the methodology for derivation of the individual types within the two classification approaches is completely different.

Association of allergic rhinitis or asthma with pollen and chemical pollutants in Szeged, Hungary, 1999-2007

The effect of biological (pollen) and chemical air pollutants on respiratory hospital admissions for the Szeged region in Southern Hungary is analysed. A 9-year (1999-2007) database includes--besides daily number of respiratory hospital admissions--daily mean concentrations of CO, PM10, NO, NO2, O3 and SO2. Two pollen variables (Ambrosia and total pollen excluding Ambrosia) are also included. The analysis was performed for patients with chronic respiratory complaints (allergic rhinitis or asthma bronchiale) for two age categories (adults and the elderly) of males and females. Factor analysis was performed to clarify the relative importance of the pollutant variables affecting respiratory complaints. Using selected low and high quantiles corresponding to probability distributions of respiratory hospital admissions, averages of two data sets of each air pollutant variable were evaluated. Elements of these data sets were chosen according to whether actual daily patient numbers were below or above their quantile value. A nonparametric regression technique was applied to discriminate between extreme and non-extreme numbers of respiratory admissions using pollen and chemical pollutants as explanatory variables. The strongest correlations between extreme patient numbers and pollutants can be observed during the pollen season of Ambrosia, while the pollen-free period exhibits the weakest relationships. The elderly group with asthma bronchiale is characterised by lower correlations between extreme patient numbers and pollutants compared to adults and allergic rhinitis, respectively. The ratio of the number of correct decisions on the exceedance of a quantile resulted in similar conclusions as those obtained by using multiple correlations.

Association of allergic asthma emergency room visits with the main biological and chemical air pollutants

Joint effect of biological (pollen) and chemical air pollutants on asthma emergency room (ER) visits was analyzed for Szeged region of Southern Hungary. Our database of a nine-year period (1999-2007) includes daily number of asthma emergency room (ER) visits, and daily mean concentrations of CO, PM(10), NO, NO(2), O(3) and SO(2), furthermore two pollen variables (Ambrosia and total pollen excluding Ambrosia), as well. The analysis was performed for ER visits of asthma bronchiale using two age groups (adults and the elderly) of males and females for three seasons. Factor analysis was performed in order to clarify the relative importance of the pollutant variables affecting asthma ER visits. Asthma ER visits denote notably stronger associations with the pollutants in adult male than in adult female patients both for the pollen season of Ambrosia and the pollen-free season. Furthermore, adults are substantially more sensitive to severe asthma attack than the elderly for the season of total pollen excluding Ambrosia pollen. The joint effect of the chemical and pollen variables is the highest for the asthma ER cases in the pollen season of Ambrosia, basically due to the extra impact of the total pollen excluding Ambrosia pollen and partly due to Ambrosia pollen. A nonparametric regression technique was applied to discriminate between events of ER visit-no ER visit using pollen and chemical pollutants as explaining variables. Based on multiple correlations, the strongest relationships between ER visits and pollutants are observed during the pollen-free season. The elderly group with asthma bronchiale is characterized by weaker relationships between ER visits and pollutants compared to adults. Ratio of the number of correct decisions on the events of ER visit-no ER visit is lowest for the season of total pollen excluding Ambrosia pollen. Otherwise, similar conclusions hold as those received by multiple correlations.

The effects of hourly differences in air pollution on the risk of myocardial infarction: case crossover analysis of the MINAP database

OBJECTIVES

To investigate associations between air pollution levels and myocardial infarction (MI) on short timescales, with data at an hourly temporal resolution.

DESIGN

Time stratified case crossover study linking clinical data from the Myocardial Ischaemia National Audit Project (MINAP) with PM(10), ozone, CO, NO(2), and SO(2) data from the UK National Air Quality Archive. Pollution effects were investigated with delays (lags) of 1-6, 7-12, 13-18, 19-24, and 25-72 hours in both single and multi-pollutant models, adjusted for ambient temperature, relative humidity, circulating levels of influenza and respiratory syncytial virus, day of week, holidays, and residual seasonality within calendar month strata.

SETTING

Population based study in 15 conurbations in England and Wales.

SUBJECTS

79,288 diagnoses of myocardial infarction recorded over the period 2003-6.

MAIN OUTCOME MEASURES

Excess risk of myocardial infarction per 10 µg/m(3) increase in pollutant level.

RESULTS

In single pollutant models, PM(10) and NO(2) levels were associated with a very short term increase in risk of myocardial infarction 1-6 hours later (excess risks 1.2% (95% confidence interval 0.3 to 2.1) and 1.1% (0.3 to 1.8) respectively per 10 μg/m(3) increase); the effects persisted in multi-pollutant models, though with only weak evidence of an independent PM(10) effect (P = 0.05). The immediate risk increases were followed by reductions in risk at longer lags: we found no evidence of any net excess risk associated with the five pollutants studied over a 72 hour period after exposure.

CONCLUSIONS

Higher levels of PM(10) and NO(2), which are typically markers of traffic related pollution, seem to be associated with transiently increased risk of myocardial infarction 1-6 hours after exposure, but later reductions in risk suggest that air pollution may be associated with bringing events forward in time ("short-term displacement") rather than increasing overall risk. The well established effect of air pollution on cardiorespiratory mortality may not be mediated through increasing the acute risk of myocardial infarction, but through another mechanism.

Can fine particulate matter explain the paradoxical ozone associations?

Our previous paper entitled "Paradoxical ozone associations could be due to methyl nitrite from combustion of methyl ethers or esters in engine fuels" (Env. Int.. 2007;33;1090) reviewed 11 studies of the impact of ozone on human health that, paradoxically, found a negative coefficient for ozone-morbidity associations. We argued that the most likely explanation for this effect would be methyl nitrite (MN) as an unsuspected exhaust component of engines with methyl ether in the fuel. The basis of the argument was the fact that MN is rapidly destroyed by sunlight, so that MN would be negatively correlated with ozone. All (but one) of the reviewed studies concluded that criterion pollutants could not explain the negative slope. The argument was strengthened by the observation that such paradoxical ozone associations have not been found in regions without significant methyl ether in gasoline. Left unaddressed in the previous paper was the possibility that fine particulate matter (FPM) might explain the POA. If this were true, then it would be necessary that the FPM be negatively correlated with ozone in those regions that found a POA. The current paper reviews data on FPM-ozone correlations in those regions where a POA was identified. The results show that FPM was, in most cases, positively correlated with ozone and so could not explain the POA.