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What can we learn today from the Central European smog episode of 1985 (and earlier episodes)?
Int. J. Hyg. Environ. Health 206 (2004); 505 ± 520 http: // www.elsevier.de/intjhyg
International Journal of Hygiene and Environmental Health
What can we learn today from the Central European smog episode of 1985 (and earlier episodes)?* H.-Erich Wichmann GSF-Institute of Epidemiology, Neuherberg, LMU Chair of Epidemiology, Munich, Germany Received February 24, 2003 ´ Revision received March 24, 2004 ´ Accepted March 28, 2004
Abstract In January 1985 an extended smog episode occurred in Central Europe. The Rhine-Ruhr area (Western Germany) was affected for 5 days with maximum concentrations of 0.8 mg/m3 SO2 and 0.6 mg/m3 TSP (24h averages). Health effects were investigated during the smog period and a control period before and after the smog. Daily mortality increased by 8%, hospital admissions (for respiratory and cardiovascular causes, RC) by 15%, outpatients (RC) by 12% and ambulance transports (RC) by 28%. Patients with chronic bronchitis from the Ruhr area cities showed more exacerbations during the episode, and in school children from the Netherlands lung function was reduced. In Augsburg (Southern Germany) the smog episode was less severe (maximum concentrations 0.2 mg/m3 SO2 and 0.1 mg/m3 TSP, 24 h averages). Here - by chance - the prospective MONICA study was ongoing. During the episode a significant increase of plasma viscosity, C-reactive protein and heart rate was observed in the participants. The highest ambient concentrations (maximum 24h average of 3.6 mg/m3 SO2) were measured in Erfurt (Eastern Germany). Surprisingly, no measurable increase of mortality occurred. This was explained by premature deaths during the period before the smog, were the concentrations had already been clearly above 1 mg/m3 SO2. An earlier episode took place in December 1962 in the Rhine-Ruhr area for 5 days with maximum concentrations of 5.0 mg/m3 SO2 and 2.4 mg/m3 TSP (24 h average). Daily mortality on average increased by 19%. In 1962 and 1985 the effects were stronger in cities with pollution mainly from traffic than in areas with pollution from industrial sources. In total, between 1962 and 1987 two major and several smaller smog episodes occurred in Central Europe. Patients with cardiovascular diseases were more severely affected than patients with respiratory diseases. Health effects were more strongly correlated with TSP than with SO2. Key words: Smog ± air pollution ± mortality ± respiratory disease ± cardiovascular disease
* This paper was presented at the Conference: ªThe Big Smokeº, December 9./10. 2002, London (LSHTP 2002). Corresponding author: Prof. Dr. Dr. H.-Erich Wichmann, GSF ± Institute of Epidemiology, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany. Phone: 49-89-3187-4066, Fax: 49-89-3187 ± 4499, E-mail: [email protected] 1438-4639/04/206/06-505 $ 30.00/0
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Introduction After the Second World War, smog became an important problem in Europe. The most severe episode took place in 1952 in London with concentrations of 4.5 mg/m3 for smoke and 3.8 mg/m3 for SO2 mainly due to domestic heating. According to the officially cited analysis, the episode was responsible for additional 4,000 deaths (Mayor of London, 2002). In Central Europe, the first smog episode after the war occurred in December 1962, and the observed mortality effects resulted in first activities of air pollution control in several countries. Western Germany experienced further episodes for more than 20 years, the last one in January 1985. The health effects observed in these episodes shall be revisited on the occasion of the 50th anniversary of the Big Smoke in London in December 1952 (LSHTM 2002).
The smog episode of January 1985 In January 1985a smog episode took place in Central Europe over a period of nearly a week. As can be seen from the model calculations of the distribution of SO2, the center of the episode was located in Eastern Germany (Figure 1). SO2 was formed to a large extend by the burning of brown coal with a high content of sulfur for heating and energy production. The emission density of SO2 in the former GDR in
Fig. 1.
the 1980s was the highest in the world, four times higher than in West Germany. The most important source was the highly industrialized triangle Leipzig, Halle, Bitterfeld. Compared to Eastern Germany, the concentration in the Rhine-Ruhr area was much lower, and it was claimed that up to 40 percent of SO2 came by far reaching transport due to Eastern winds. Part of the episode was seen in the Netherlands, where a large proportion of the pollution also came from the East, namely from the Ruhr area. Lower concentrations were seen in the south of Germany.
Rhine-Ruhr area (Western Germany) In the Rhine-Ruhr area the smog episode built up starting on January 15 and 16, 1985. The maximum occurred on January 17 to 20. The episode was caused by an inversion of vertical temperature gradient from January 16 to 20 with a wind velocity below 1.5 m/ sec. During this time pollutants accumulated. The inversion stopped on January 21 and fresh wind came up. During the first part of the smog period (January 17 ± 20) it was cold with temperatures between minus 4 and minus 128C (daily average). The temperature increased steeply on January 21. The smog episode was characterized by elevated levels of SO2 and TSP (total suspended particles). In the Rhine-Ruhr-area, for SO2 a daily average of 830 mg/m3 and a daily maximum (30 min value) of 2170 mg/m3 was reached. For TSP the corresponding
Smog episode in Central Europe on January 20, 1985. Simulation of ambient SO2-concentrations (RIVM 1985)
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Fig. 2. Areas, as defined for the investigation of health effects of the smog episode 1985. The polluted area corresponds to the Rhine-Ruhr-area (Wichmann et al. 1989).
Fig. 4. Time course of daily means of temperature, pollutants, hospital admissions (RC) and total mortality in the control area during the smog episode 1985. Hashed: time of smog alarm (Wichmann et al. 1989).
Fig. 3. Time course of daily means of temperature, pollutants, hospital admissions (RC) and total mortality in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. Hashed: time of smog alarm (Wichmann et al. 1989).
concentrations were 600 mg/m3 (daily average) and 850 mg/m3 (3 hours value). To investigate health effects, data from different sources were collected retrospectively shortly after the episode. The data then were analyzed for the six
complete weeks between January 2 and February 13. The week from January 17 to 23 was referred to as the smog period. This week included the period of smog alarm (January 17 to 21) and the two following days. The rationale for this definition was the experience from earlier smog episodes that health effects might follow with the delay of one to two days. The other five weeks were considered as control period. Mortality data were collected by the public health administrations of the communities and counties in North-Rhine Westphalia and coded by ICD. In addition, deaths by respiratory or cardiovascular diseases were coded separately. These diagnoses were either denoted on the death certificate as cause of death or as consecutive disease. In total, data from 24,000 deaths (94% of all) were available. Data on hospital admissions were requested by questionnaires, which had been sent to all hospitals for internal medicine and pediatrics in North Rhine Westphalia. One hundred and eighty-six hospitals (45% of all) participated in the study. Individual information about the clinical diagnoses and the severity of symptoms was collected for about 13,000 patients with respiratory or cardiovascular diseases (RC).
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Fig. 5. Increase of total mortality, ambulance transports (RC), outpatients (RC) and hospital admissions (RC) in the polluted area (RhineRuhr-area) and the control area during the smog episode 1985, in Northrhine Westfalia (Wichmann et al. 1989).
Data regarding patients delivered by ambulance transport to the hospitals were collected by extraction from the records of the ambulance control centers. The diagnoses of these patients then were completed from the hospital records. For seven big cities in the Rhine-Ruhr area individual data from 1500 patients with respiratory or cardiovascular diseases, delivered to 78 hospitals, were collected. One hundred and nine hospitals also filled in questionnaires about visits of outpatients in their emergency rooms. These ambulances are mainly consulted by the patients' own decision rather than by doctor's advice. In total, aggregated data of 5,400 outpatients with respiratory or cardiovascular diseases were collected. All data was analyzed for three areas (Figure 2): 1. The polluted area which was the Ruhr area and the cities of Düsseldorf and Köln (6 million inhabitants). 2. The control area defined by the eastern and southern parts of North Rhine Westphalia (6 million inhabitants). 3. The intermediate area between the polluted and the control area (4 million inhabitants).
In the polluted area, an increase of both the number of deaths and the number of patients with health problems was observed, which was parallel to the increase of the pollutants. The maximum of mortality and hospital admissions was reached 1 to 2 days after the onset of the smog episode (Figure 3). No comparable patterns were found in the control area, where the concentrations of the pollutants were lower (Figure 4). Regression analysis identified a considerable contribution of air pollution to the explanation of the medical observations. This contribution was highly significant for the maxima of ambient concentrations for the same day and for the daily averages with a delay of 2 days. If one compared the smog period to the average of the other weeks one found a significant increase for total mortality, hospital admissions, outpatients and ambulance transport of patients with respiratory or cardiovascular diseases (RC) in the polluted area. This can also be seen by the parallel increase in the smoothened time courses during the episode and the parallel decreases thereafter (Figure 5). For total mortality there was a significant increase by 8% in the polluted area but only by 2% in the control area (Figure 6). Looking at cause-specific
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Fig. 6. Increase of total mortality and hospital admissions of patients with respiratory/cardiovascular diseases (RC) in the polluted, intermediate and control area of Northrhine Westfalia during the smog episode 1985 (Wichmann et al. 1987).
Fig. 7. Increase of the hospital admissions of patients with respiratory/cardiovascular diseases (RC) for higher age groups in the polluted area (Rhine-Ruhr-area) during the smog episode 1985 (Wichmann et al. 1987).
mortality, the clearest increase was observed for deaths by cardiovascular diseases, while for respiratory diseases only a small effect was found. Looking at single diagnoses, deaths by heart insufficiency, myocardial infarction, cerebral circulation failure
increased in the polluted area (Table 1) but not in the control area. For hospital admissions a significant increase by 15% in the polluted area was found and by 3% in the control area in the smog period (Figure 6). The most
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Table 1. Increase of total and cause-specific mortality in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. The analysis is based on 24.000 death certificates (from Wichmann et al. 1989).
Table 3. Increase of ambulance transports of patients with respiratory/cardiovascular diseases (RC) in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. The analysis is based on 1.500 RC transports (from Wichmann et al. 1989).
Total mortality
8%**
Total RC
28%**
Heart insufficiency Myocardial infarction Cardiovascular diseases Cerebral circulation failure Respiratory diseases
19%* 9% 6% 5% 3%
Cardiovascular diseases Respiratory diseases
25%** 36%**
* p < 0.05; ** p < 0.01
Table 2. Increase of hospital admissions of patients with respiratory/cardiovascular diseases (RC) in the polluted area (Rhine-Ruhrarea) during the smog episode 1985. The analysis is based on 13.000 RC admissions (from Wichmann et al. 1989). Total RC
15%**
Cerebral circulation failure Chronic bronchitis Coronary insufficiency Cardiovascular diseases Heart insufficiency Myocardial infarction Respiratory diseases Bronchial asthma
57%** 39%* 30%* 19%** 14%* 10% 7% 14%
* p < 0.05; ** p < 0.01
pronounced effects were seen for cerebral circulation failure (significant), chronic bronchitis and coronary insufficiency. Interestingly, for asthma no increase but a (non-significant) decrease was observed (Table 2). The number of patients with respiratory or cardiovascular diseases which were transported by ambulances into hospitals showed the strongest increase of all health endpoints considered in the study, namely 28% in the polluted area. The effect was stronger for patients with respiratory diseases (36%) than for those with cardiovascular diseases (25%, Table 3). The number of recorded outpatients with respiratory and cardiovascular diseases was elevated by 12% in the polluted area and by 5% in the control area (Figure 6). There is a considerable internal consistency of the results: if one compares the control area, the intermediate area, and the polluted area, total mortality increased by 2, 5 and 8% and hospital admissions by 4, 7 and 15% in the respective areas (Figure 7). Furthermore, the effects of mortality were stronger for older ages (Figure 8). There was an indication of a harvesting effect: if one looks at the time course, it is obvious that after
* p < 0.05; ** p < 0.01
the increase there was a decrease in mortality rates about 14 days after the episode (Figure 5). This might indicate a reduced mortality due to premature deaths. A further result points into the same direction: about 10 days before the smog episode there was an extreme cold period on January 7 and 8. This resulted in increased mortality, comparable to that of the smog episode. Even more interesting, it could be shown that based on isotherms in those counties with temperatures below 13 8C the mortality increased by 46%, whereas in counties with temperatures of 9 8C or above the increase of mortality was only 14%. Inversely, in the areas where mortality increased only moderately in the cold period, there was a strong increase during the smog episode, whereas in the areas where during the cold days mortality had increased strongly, no increase was observed in connection with the smog episode (Figure 9). Two prospective investigations were ongoing during the smog episode 1985. Meister at al. (1987) performed a multi center cohort study in the Rhine-Ruhr area and other regions. In 181 patients with chronic bronchitis they found an increase of exacerbation in the polluted area during the smog episode in parallel to the increase of the pollution (Figure 10). In addition, Dassen et al. (1986) found in school children in the Netherlands a significant decrease of several lung function parameters in the smog episode in January 1985 compared to February 1985, after adjustment for the relevant covariates.
Erfurt (Eastern Germany) Although it was not possible to investigate the smog episode in East Germany at the time of occurrence, we had the chance to do this later after German reunification. This analysis was performed as part of a more extended study on air pollution and daily mortality in Erfurt from 1980 to 1989 (Spix et al. 1993). Erfurt was one of the cities in East Germany
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Fig. 8. Time course of moving 7 day average of total mortality hospital admissions (RC), ambulance transports (RC) and outpatients (RC) in the polluted area (Rhine-Ruhr-area) during the smog episode 1985, Hashed: time of smog alarm (Wichmann et al. 1989).
Fig. 9. Comparison of the effect of severe cold and the smog episode on total mortality in Northrhine Westfalia: In areas where many additional deaths occurred during the severe cold, only minor effects were seen during the smog episode and vice versa (Wichmann et al. 1987).
with very high ambient pollution. The city is surrounded by ridges approximately 100 m higher in all directions except north. There are frequent inversions and trapping of air pollutants in this bowl. In the study SO2 measurements (daily mean and daily maxima) were available for the whole
period (Figure 11), whereas measurements of TSP (daily mean) were only available for the years 1988 to 1989 (Figure 12). The analysis covered several smog episodes which regularly occurred during winter time in the 10 years period. This can be seen by the daily averages of SO2 reaching between 1000
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Fig. 10. 1987).
Exacerbations of chronic bronchitis in a prospective panel study during the smog episode 1985, Rhine-Ruhr-area (Meister et al.
Fig. 11.
Daily SO2-concentrations 1985 ± 1989 in Erfurt (Eastern Germany) (Spix et al. 1993).
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Fig. 12.
Daily TSP concentrations 1988 ± 1989 in Erfurt (Spix et al. 1993).
Fig. 13.
Logarithmic association between TSP and SO2 and total mortality in Erfurt (Spix et al. 1993).
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Fig. 14. Total mortality in Erfurt in association with SO2 and TSP 1980 ± 1989. Comparison of 95 percentile with 5 percentile of the distribution of the pollutants (Spix et al. 1993).
Fig. 15. Premature deaths due to high pollution with a lag of 15 days. Comparison of 95 percentile and 5 percentile of the distribution of the pollutants (Spix et al. 1993).
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Fig. 16.
Theoretical increase of total mortality during the smog episode 1985 in the Rhine-Ruhr-area and Erfurt (Spix et al. 1993).
Fig. 17. 1993).
Theoretical and observed increase in total mortality during the smog episode 1985 in the Rhine Ruhr area and Erfurt (Spix et al.
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Table 4. Smog episode 1985 in Augsburg (Southern Germany).
Winter 84/85 (without episode) Air pollution episode Winter 87/88
SO2 [mg/m3]
TSP [mg/m3]
48.1 (13 to 103) 200.3 (160 to 238) 23.6 (6 to 71)
47.4 (7 to 135) 97.7 (62 to 176) 48.3 (12 to 134)
Table 5. Increase in plasma viscosity and C reactive protein (CRP) in participants* of the MONICA Study Augsburg during the smog episode 1985 (from Peters et al. 1997, 1999). Odds Ratios:
Plasma viscosity > 90th percentile
95% CI
CRP > 90th percentile
95% CI
Episode SO2 (80 mg/m3) TSP (90 mg/m3)
1.99 1.39 1.65
1.10 to 3.60 0.92 to 2.09 0.81 to 3.40
3.57** 1.80 2.31
0.68 to 18.7 1.09 to 2.96 1.29 to 4.13
* 631 men aged 45 to 64; ** adjusted for TSP
Table 6. Increase of heart rate and blood pressure in participants of the MONICA Study Augsburg during the smog episode 1985 (from Peters et al. 1997, 1999).
Episode SO2 (80 mg/m3) TSP (90 mg/m3)
Change in Heart Rate [bpm]
95% CI
Change in Systolic Blood Pressure [mmHg]
1.79 1.04 1.56
0.72 to 2.87 0.60 to 1.49 0.68 to 2.43
0.19 0.70 1.78
and 3600 mg/m3. The daily maxima for TSP were 650 in 1988 and 618 mg/m3 in 1989. There was a logarithmic rather than a linear exposure response relationship for SO2 and TSP (Figure 13), and the association of mortality with TSP was stronger than with SO2 (Figure 14). Furthermore, there was a clear indication of premature mortality. High mortality two weeks before led to a smaller effect of air pollution than low mortality two weeks before. This ªharvesting effectº was much stronger for TSP than for SO2 (Figure 15). Two pollutant models including SO2 and TSP could only be applied since 1988. The calculations showed that the parameter for SO2 was reduced to close to zero while the parameter for TSP only decreased slightly (Spix et al. 1993). We also tried to understand why there was a strong effect on daily mortality in the Ruhr area with SO2 concentrations below 1000 mg/m3, whereas there was nearly no effect in Erfurt with SO2 concentrations of more than 3000 mg/m3. This surprising result could be explained by the logarithmic form of the exposure response relationship. Since in the Rhine-Ruhr area both the concentration of SO2 and
95% CI
1.27 to 1.66 0.09 to 1.30 0.67 to 2.88
mortality were low before the episode, an increase of mortality by 8% easily can be understood (Figures 16, 17). However, in Erfurt both the SO2 concentration and mortality were already very high before the episode, and the episode itself could only add a small effect. The model calculation (Figure 16) resulted in a theoretical increase in mortality by about 2% which could not be identified empirically for statistical reasons.
Augsburg (Southern Germany) By chance during the 1985 smog period a health survey was performed in Augsburg, Southern Germany within the MONICA (monitoring of determinants of cardiovascular diseases) project of WHO. Although air pollution was moderate (highest daily mean of TSP was 100 mg/m3, and of SO2 it was 200 mg/m3, Table 4), this was a unique opportunity to analyze smog effects on sensitive cardiovascular parameters, which were prospectively collected.
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Table 7. Comparison of pollution and daily mortality during four episodes 1962-1985 in the Rhine-Ruhr-area (from Wichmann et al. 1989). Episode (duration)
Dec. 1962 (5 days)
SO2 [mg/m3] 30-min value 3-hr value 24-hr value
5.0
TSP [mg/m ] 3-hr value 24-hr value
2.4
Jan. 1979 (1 day)
Jan. 1982 (6 days)
Jan. 1985 (5 days)
1.4 1.1 0.6
1.1 0.9 0.6
2.2 1.6 0.8
0.5
0.6 0.5
0.8 0.6
none
none
8%
3
Increase of total mortality
Fig. 18.
19%
Increase in total mortality during the smog episode of 1962 (Steiger and Brockhaus et al. 1971).
During the episode, the distribution of plasma viscosity and C-reactive protein (CRP) measured in the study participants in Augsburg were shifted to the right. For plasma viscosity above the 90th percentile, the OR increased significantly to 1.99 and for CRP to 3.57 (Table 5). The heart rate increased significantly by 1.8 beats per minute and the blood pressure also increased slightly (Table 6). The voltage at the ST segment pointed towards a systemic reaction which might precipitate ischemic events. When SO2 and TSP were compared, TSP showed stronger associations for all health endpoints (Peters et al. 1997, 1999a and b).
Earlier smog episodes (1962, 1979, 1982) The episode with the highest ambient concentrations in Central Europe occurred in December 1962. It lasted for five days. In the Rhine-Ruhr-area the pollutants reached daily means of 5000 mg/m3 SO2 and 2400 mg/m3 TSP (Table 7). During this episode the number of deaths increased significantly in the week from the beginning of the smog compared to the control period (Steiger and Brockhaus 1971, Figure 18). While the daily mortality at the Ruhr
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Fig. 19.
Increase of total mortality by area during the smog episode of 1962 in Northrhine Westfalia (Steiger and Brockhaus 1971).
Fig. 20.
Increase of total mortality by area during the smog episode 1985 in Northrhine Westfalia (Wichmann et al. 1989).
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increased by 19%, there was an increase by 25% in the city of Köln and nearly no change in the rural parts of Northrhine Westfalia (Figure 19). This pattern was very similar to that of the 1985 episode (Figure 20). It should be noted, that during the same episode in December 1962 in London air pollution also was high, followed by an increase of mortality by 20%, corresponding to 340 additional deaths (Scott 1963). In 1979 during a one day smog episode concentrations of 600 mg/m3 SO2 and 500 mg/m3 TSP (3 hours average) were reached, but no increase of mortality could be found (Steiger 1980, Table 7). In 1982, a local smog episode of 6 days was reported in the center of the Ruhr area where 600 mg/ m3 SO2 and 500 mg/m3 TSP (24 hours averages) and also high concentrations of NO2 and CO were reached (Külske 1982). The analyses of the mortality data of this small area did not show an observable effect (Wichmann et. al.1989, Table 7). During this episode, also a mortality analysis was performed in West-Berlin (Borgers und Heberling 1982). The authors also did not find an effect on mortality. In Berlin the maximum SO2 concentration was 864 mg/ m3 and the maximum TSP concentration 395 mg/m3 (24 hour averages). The episode lasted from January 11 to 22, 1982.
Discussion Compared to the smog episodes in London, smaller (but nevertheless important) episodes occurred in Central Europe. In December 1952, no elevated air pollution had been reported for Germany, probably due to the fact that the industry was destroyed after the war and no source of air pollution comparable to London was available. Furthermore, no ambient measurements were performed. This was different at the beginning of the 1960s when the German industry had been reestablished. Therefore, the episode of 1962 occurred both in London and at the Ruhr with comparable effects. Several smaller episodes were observed in the 1970s and 1980s, until 1985 the last big episode occurred in Central Europe. Interestingly, the effects observed in the region with the highest pollution, namely Eastern Germany, were only minor. Only mortality data were available there, and these data did not show any effect of the episode. Our interpretation is that the concentration of air pollutants was already very high before the episode so that the additional increase did not lead to further deaths. This might be explained by premature deaths, i.e. frail people
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dying a few days earlier. This phenomenon has been described during the 1980s in Eastern and Western Germany. However, in later years with much lower ambient concentrations it was not observed anymore. Interestingly, as a rule stronger effects were seen for cardiac endpoints compared to respiratory endpoints. In general, patients with existing diseases or reduced health status were at higher risk. Patients with allergy-related diseases like asthma or croup syndrome seemed not to be affected. It is a curiosity, that in an area with relatively low concentrations during the smog episode, namely Augsburg, the most interesting effects were found. This is due to the fact that a large survey was performed at the time when the smog episode occurred. Therefore it was possible to analyze sensitive parameters which were not available at the places of the higher concentrations. In Augsburg, significant effects on plasma viscosity, C-reactive protein and heart rate were observed. Although in the discussed episodes SO2 seemed to be an important pollutant, meanwhile it is clear that SO2 probably was an indicator rather than a causal agent. This is supported by the fact that in two pollutant models already at that time TSP had a stronger influence than SO2. Furthermore, SO2 decreased over the years enormously by a factor of 100 or even more. Nevertheless, even today associations of health endpoints with SO2 are observable (Wichmann et al. 2000). There is no indication that these low concentrations of SO2 can be relevant, based on animal experiments and controlled human exposure. Therefore, SO2 even today seems to be an indicator of a different causal agent, which most probably is related to particles. One also has to keep in mind that TSP from our today knowledge probably is not the most relevant particle metrics. Smaller particles, as measured by PM10 or PM2.5 or the number count of ultrafine particles, which are subgroups of TSP, seem to be more relevant, but these were not measured in earlier years. In total, from these earlier episodes lessons can be learned which are still relevant for today's research: 1) There were more immediate effects on respiratory endpoints (as seen for ambulance transports) and more (by few days) delayed effects on cardiovascular endpoints (as seen for hospital admissions and mortality). 2) Cardiovascular effects were stronger than respiratory effects. 3) In places with high traffic pollution (Köln, Düsseldorf, Augsburg) the effects were stronger
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than in areas with `classical' pollution from industry (Ruhr area) or domestic heating (Erfurt). 4) Particles showed stronger effects than SO2. Today particulate matter is considered to be the most relevant ambient pollutant with respect to health effects - but we think of PM10, PM2.5 and particle number rather than of TSP. Furthermore, interest in epidemiological and toxicological research on particles has been shifted from the lung to the heart and the circulation, and we discuss influences on the autonomous nervous system, inflammatory parameters and translocation of ultrafine particles into the blood stream (Wichmann et al. 2002, WHO 2003). Thus, retrospectively seen, these modern developments are based on the smog history of earlier decades.
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3rd colloquium on particulate air pollution and human health, June 6 ± 8 1999. Durham NC 1999a. Peters, A., Perz, S., Döring, A., Stieber, J., Koenig, W., Wichmann, H.-E.: Increases in heart rate during an air pollution episode. Am J Epidemiol 150, 1094 ± 1098 (1999b). RIVM (1985) in: de Leew F. A. A. M., van Rheineck Leyssius H. J.: Long range transport modeling of air pollution episodes. Environ Health Perspect 79, 553 ± 59 (1989). Schmitt, O. A.: Smogepisoden im Ruhrgebiet seit 1980 (Smog episodes in the Ruhr district since 1980). In: Smog Episodes (G. von Nieding, K. Jander, eds.) pp. 119 ± 128. Fischer Verlag, Stuttgart 1986. Scott: The London fog of December 1962. Med. Officer 109, 250 ± 252 (1963). Spix, C., Heinrich, J., Dockery, D., Schwartz, J., Völksch, G., Schwinkowski, K., Göllen, C., Wichmann, H.-E.: Air pollution and daily mortality in Erfurt, East Germany, from 1980 ± 1989. Environ Health Perspect 101, 518 ± 526 (1993). Steiger, H., Brockhaus, A.: Untersuchungen zur Mortalität in NRW während der Inversionswetterlage Dezember 1962 (Investigations on mortality in North-Rhine Westfalia during the inversion-weather situation in December 1962). Staub-Reinhaltung der Luft 31, 190 ± 192 (1971). Steiger, H.: Mortalitätsuntersuchung während der Smogwetterlage im westlichen Ruhrgebiet am 17. Januar 1979 (Investigation on mortality during the smog period in the Western Ruhr District on January 17, 1979). Zbl Bact Hyg B 171, 445 ± 744 (1980). WHO Health aspects of air pollution with particulate matter, ozone and nitrogen dioxide. Report from WHO working group meeting Bonn, 13.±15. January 2003. WHO Regional Office for Europe, Copenhagen (2003). Wichmann, H.-E., Heinrich, J., Peters, A.: Gesundheitliche Auswirkungen von Feinstaub (Health effects of fine particulate matter) ecomed Verlag, Landsberg 2002. Wichmann, H.-E., Mueller, W., Allhoff, P., Beckmann, M., Bocter, N., Csicsaky, M. J., Jung, M., Molik, B., Schoeneberg, G.: Health effects during a smog episode in West Germany in 1985. Environ Health Perspect 79, 89 ± 99 (1989). Wichmann, H.-E., Spix, C., Mücke, G.: Kleinräumige Analyse der Smogepisode des Januar 1985 unter Berücksichtigung meteorologischer Einflüsse (Small area analysis of the smog episode of January 1985 considering meteorological influences). Ministry of Labor, Health and Social Affairs Germany, Düsseldorf 1987. Wichmann, H.-E., Spix, C., Tuch, T., Wölke, G., Peters, A., Heinrich, J., Kreyling, G., Heyder, J.: Daily Mortality and Fine and Ultrafine Particles in Erfurt, Germany. Part I: Role of Particle Number and Particle Mass. Health Effects Institute. Research Report No. 98, Boston 2000.
International Journal of Hygiene and Environmental Health
What can we learn today from the Central European smog episode of 1985 (and earlier episodes)?* H.-Erich Wichmann GSF-Institute of Epidemiology, Neuherberg, LMU Chair of Epidemiology, Munich, Germany Received February 24, 2003 ´ Revision received March 24, 2004 ´ Accepted March 28, 2004
Abstract In January 1985 an extended smog episode occurred in Central Europe. The Rhine-Ruhr area (Western Germany) was affected for 5 days with maximum concentrations of 0.8 mg/m3 SO2 and 0.6 mg/m3 TSP (24h averages). Health effects were investigated during the smog period and a control period before and after the smog. Daily mortality increased by 8%, hospital admissions (for respiratory and cardiovascular causes, RC) by 15%, outpatients (RC) by 12% and ambulance transports (RC) by 28%. Patients with chronic bronchitis from the Ruhr area cities showed more exacerbations during the episode, and in school children from the Netherlands lung function was reduced. In Augsburg (Southern Germany) the smog episode was less severe (maximum concentrations 0.2 mg/m3 SO2 and 0.1 mg/m3 TSP, 24 h averages). Here - by chance - the prospective MONICA study was ongoing. During the episode a significant increase of plasma viscosity, C-reactive protein and heart rate was observed in the participants. The highest ambient concentrations (maximum 24h average of 3.6 mg/m3 SO2) were measured in Erfurt (Eastern Germany). Surprisingly, no measurable increase of mortality occurred. This was explained by premature deaths during the period before the smog, were the concentrations had already been clearly above 1 mg/m3 SO2. An earlier episode took place in December 1962 in the Rhine-Ruhr area for 5 days with maximum concentrations of 5.0 mg/m3 SO2 and 2.4 mg/m3 TSP (24 h average). Daily mortality on average increased by 19%. In 1962 and 1985 the effects were stronger in cities with pollution mainly from traffic than in areas with pollution from industrial sources. In total, between 1962 and 1987 two major and several smaller smog episodes occurred in Central Europe. Patients with cardiovascular diseases were more severely affected than patients with respiratory diseases. Health effects were more strongly correlated with TSP than with SO2. Key words: Smog ± air pollution ± mortality ± respiratory disease ± cardiovascular disease
* This paper was presented at the Conference: ªThe Big Smokeº, December 9./10. 2002, London (LSHTP 2002). Corresponding author: Prof. Dr. Dr. H.-Erich Wichmann, GSF ± Institute of Epidemiology, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany. Phone: 49-89-3187-4066, Fax: 49-89-3187 ± 4499, E-mail: [email protected] 1438-4639/04/206/06-505 $ 30.00/0
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Introduction After the Second World War, smog became an important problem in Europe. The most severe episode took place in 1952 in London with concentrations of 4.5 mg/m3 for smoke and 3.8 mg/m3 for SO2 mainly due to domestic heating. According to the officially cited analysis, the episode was responsible for additional 4,000 deaths (Mayor of London, 2002). In Central Europe, the first smog episode after the war occurred in December 1962, and the observed mortality effects resulted in first activities of air pollution control in several countries. Western Germany experienced further episodes for more than 20 years, the last one in January 1985. The health effects observed in these episodes shall be revisited on the occasion of the 50th anniversary of the Big Smoke in London in December 1952 (LSHTM 2002).
The smog episode of January 1985 In January 1985a smog episode took place in Central Europe over a period of nearly a week. As can be seen from the model calculations of the distribution of SO2, the center of the episode was located in Eastern Germany (Figure 1). SO2 was formed to a large extend by the burning of brown coal with a high content of sulfur for heating and energy production. The emission density of SO2 in the former GDR in
Fig. 1.
the 1980s was the highest in the world, four times higher than in West Germany. The most important source was the highly industrialized triangle Leipzig, Halle, Bitterfeld. Compared to Eastern Germany, the concentration in the Rhine-Ruhr area was much lower, and it was claimed that up to 40 percent of SO2 came by far reaching transport due to Eastern winds. Part of the episode was seen in the Netherlands, where a large proportion of the pollution also came from the East, namely from the Ruhr area. Lower concentrations were seen in the south of Germany.
Rhine-Ruhr area (Western Germany) In the Rhine-Ruhr area the smog episode built up starting on January 15 and 16, 1985. The maximum occurred on January 17 to 20. The episode was caused by an inversion of vertical temperature gradient from January 16 to 20 with a wind velocity below 1.5 m/ sec. During this time pollutants accumulated. The inversion stopped on January 21 and fresh wind came up. During the first part of the smog period (January 17 ± 20) it was cold with temperatures between minus 4 and minus 128C (daily average). The temperature increased steeply on January 21. The smog episode was characterized by elevated levels of SO2 and TSP (total suspended particles). In the Rhine-Ruhr-area, for SO2 a daily average of 830 mg/m3 and a daily maximum (30 min value) of 2170 mg/m3 was reached. For TSP the corresponding
Smog episode in Central Europe on January 20, 1985. Simulation of ambient SO2-concentrations (RIVM 1985)
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Fig. 2. Areas, as defined for the investigation of health effects of the smog episode 1985. The polluted area corresponds to the Rhine-Ruhr-area (Wichmann et al. 1989).
Fig. 4. Time course of daily means of temperature, pollutants, hospital admissions (RC) and total mortality in the control area during the smog episode 1985. Hashed: time of smog alarm (Wichmann et al. 1989).
Fig. 3. Time course of daily means of temperature, pollutants, hospital admissions (RC) and total mortality in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. Hashed: time of smog alarm (Wichmann et al. 1989).
concentrations were 600 mg/m3 (daily average) and 850 mg/m3 (3 hours value). To investigate health effects, data from different sources were collected retrospectively shortly after the episode. The data then were analyzed for the six
complete weeks between January 2 and February 13. The week from January 17 to 23 was referred to as the smog period. This week included the period of smog alarm (January 17 to 21) and the two following days. The rationale for this definition was the experience from earlier smog episodes that health effects might follow with the delay of one to two days. The other five weeks were considered as control period. Mortality data were collected by the public health administrations of the communities and counties in North-Rhine Westphalia and coded by ICD. In addition, deaths by respiratory or cardiovascular diseases were coded separately. These diagnoses were either denoted on the death certificate as cause of death or as consecutive disease. In total, data from 24,000 deaths (94% of all) were available. Data on hospital admissions were requested by questionnaires, which had been sent to all hospitals for internal medicine and pediatrics in North Rhine Westphalia. One hundred and eighty-six hospitals (45% of all) participated in the study. Individual information about the clinical diagnoses and the severity of symptoms was collected for about 13,000 patients with respiratory or cardiovascular diseases (RC).
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Fig. 5. Increase of total mortality, ambulance transports (RC), outpatients (RC) and hospital admissions (RC) in the polluted area (RhineRuhr-area) and the control area during the smog episode 1985, in Northrhine Westfalia (Wichmann et al. 1989).
Data regarding patients delivered by ambulance transport to the hospitals were collected by extraction from the records of the ambulance control centers. The diagnoses of these patients then were completed from the hospital records. For seven big cities in the Rhine-Ruhr area individual data from 1500 patients with respiratory or cardiovascular diseases, delivered to 78 hospitals, were collected. One hundred and nine hospitals also filled in questionnaires about visits of outpatients in their emergency rooms. These ambulances are mainly consulted by the patients' own decision rather than by doctor's advice. In total, aggregated data of 5,400 outpatients with respiratory or cardiovascular diseases were collected. All data was analyzed for three areas (Figure 2): 1. The polluted area which was the Ruhr area and the cities of Düsseldorf and Köln (6 million inhabitants). 2. The control area defined by the eastern and southern parts of North Rhine Westphalia (6 million inhabitants). 3. The intermediate area between the polluted and the control area (4 million inhabitants).
In the polluted area, an increase of both the number of deaths and the number of patients with health problems was observed, which was parallel to the increase of the pollutants. The maximum of mortality and hospital admissions was reached 1 to 2 days after the onset of the smog episode (Figure 3). No comparable patterns were found in the control area, where the concentrations of the pollutants were lower (Figure 4). Regression analysis identified a considerable contribution of air pollution to the explanation of the medical observations. This contribution was highly significant for the maxima of ambient concentrations for the same day and for the daily averages with a delay of 2 days. If one compared the smog period to the average of the other weeks one found a significant increase for total mortality, hospital admissions, outpatients and ambulance transport of patients with respiratory or cardiovascular diseases (RC) in the polluted area. This can also be seen by the parallel increase in the smoothened time courses during the episode and the parallel decreases thereafter (Figure 5). For total mortality there was a significant increase by 8% in the polluted area but only by 2% in the control area (Figure 6). Looking at cause-specific
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Fig. 6. Increase of total mortality and hospital admissions of patients with respiratory/cardiovascular diseases (RC) in the polluted, intermediate and control area of Northrhine Westfalia during the smog episode 1985 (Wichmann et al. 1987).
Fig. 7. Increase of the hospital admissions of patients with respiratory/cardiovascular diseases (RC) for higher age groups in the polluted area (Rhine-Ruhr-area) during the smog episode 1985 (Wichmann et al. 1987).
mortality, the clearest increase was observed for deaths by cardiovascular diseases, while for respiratory diseases only a small effect was found. Looking at single diagnoses, deaths by heart insufficiency, myocardial infarction, cerebral circulation failure
increased in the polluted area (Table 1) but not in the control area. For hospital admissions a significant increase by 15% in the polluted area was found and by 3% in the control area in the smog period (Figure 6). The most
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Table 1. Increase of total and cause-specific mortality in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. The analysis is based on 24.000 death certificates (from Wichmann et al. 1989).
Table 3. Increase of ambulance transports of patients with respiratory/cardiovascular diseases (RC) in the polluted area (Rhine-Ruhr-area) during the smog episode 1985. The analysis is based on 1.500 RC transports (from Wichmann et al. 1989).
Total mortality
8%**
Total RC
28%**
Heart insufficiency Myocardial infarction Cardiovascular diseases Cerebral circulation failure Respiratory diseases
19%* 9% 6% 5% 3%
Cardiovascular diseases Respiratory diseases
25%** 36%**
* p < 0.05; ** p < 0.01
Table 2. Increase of hospital admissions of patients with respiratory/cardiovascular diseases (RC) in the polluted area (Rhine-Ruhrarea) during the smog episode 1985. The analysis is based on 13.000 RC admissions (from Wichmann et al. 1989). Total RC
15%**
Cerebral circulation failure Chronic bronchitis Coronary insufficiency Cardiovascular diseases Heart insufficiency Myocardial infarction Respiratory diseases Bronchial asthma
57%** 39%* 30%* 19%** 14%* 10% 7% 14%
* p < 0.05; ** p < 0.01
pronounced effects were seen for cerebral circulation failure (significant), chronic bronchitis and coronary insufficiency. Interestingly, for asthma no increase but a (non-significant) decrease was observed (Table 2). The number of patients with respiratory or cardiovascular diseases which were transported by ambulances into hospitals showed the strongest increase of all health endpoints considered in the study, namely 28% in the polluted area. The effect was stronger for patients with respiratory diseases (36%) than for those with cardiovascular diseases (25%, Table 3). The number of recorded outpatients with respiratory and cardiovascular diseases was elevated by 12% in the polluted area and by 5% in the control area (Figure 6). There is a considerable internal consistency of the results: if one compares the control area, the intermediate area, and the polluted area, total mortality increased by 2, 5 and 8% and hospital admissions by 4, 7 and 15% in the respective areas (Figure 7). Furthermore, the effects of mortality were stronger for older ages (Figure 8). There was an indication of a harvesting effect: if one looks at the time course, it is obvious that after
* p < 0.05; ** p < 0.01
the increase there was a decrease in mortality rates about 14 days after the episode (Figure 5). This might indicate a reduced mortality due to premature deaths. A further result points into the same direction: about 10 days before the smog episode there was an extreme cold period on January 7 and 8. This resulted in increased mortality, comparable to that of the smog episode. Even more interesting, it could be shown that based on isotherms in those counties with temperatures below 13 8C the mortality increased by 46%, whereas in counties with temperatures of 9 8C or above the increase of mortality was only 14%. Inversely, in the areas where mortality increased only moderately in the cold period, there was a strong increase during the smog episode, whereas in the areas where during the cold days mortality had increased strongly, no increase was observed in connection with the smog episode (Figure 9). Two prospective investigations were ongoing during the smog episode 1985. Meister at al. (1987) performed a multi center cohort study in the Rhine-Ruhr area and other regions. In 181 patients with chronic bronchitis they found an increase of exacerbation in the polluted area during the smog episode in parallel to the increase of the pollution (Figure 10). In addition, Dassen et al. (1986) found in school children in the Netherlands a significant decrease of several lung function parameters in the smog episode in January 1985 compared to February 1985, after adjustment for the relevant covariates.
Erfurt (Eastern Germany) Although it was not possible to investigate the smog episode in East Germany at the time of occurrence, we had the chance to do this later after German reunification. This analysis was performed as part of a more extended study on air pollution and daily mortality in Erfurt from 1980 to 1989 (Spix et al. 1993). Erfurt was one of the cities in East Germany
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Fig. 8. Time course of moving 7 day average of total mortality hospital admissions (RC), ambulance transports (RC) and outpatients (RC) in the polluted area (Rhine-Ruhr-area) during the smog episode 1985, Hashed: time of smog alarm (Wichmann et al. 1989).
Fig. 9. Comparison of the effect of severe cold and the smog episode on total mortality in Northrhine Westfalia: In areas where many additional deaths occurred during the severe cold, only minor effects were seen during the smog episode and vice versa (Wichmann et al. 1987).
with very high ambient pollution. The city is surrounded by ridges approximately 100 m higher in all directions except north. There are frequent inversions and trapping of air pollutants in this bowl. In the study SO2 measurements (daily mean and daily maxima) were available for the whole
period (Figure 11), whereas measurements of TSP (daily mean) were only available for the years 1988 to 1989 (Figure 12). The analysis covered several smog episodes which regularly occurred during winter time in the 10 years period. This can be seen by the daily averages of SO2 reaching between 1000
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Fig. 10. 1987).
Exacerbations of chronic bronchitis in a prospective panel study during the smog episode 1985, Rhine-Ruhr-area (Meister et al.
Fig. 11.
Daily SO2-concentrations 1985 ± 1989 in Erfurt (Eastern Germany) (Spix et al. 1993).
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Fig. 12.
Daily TSP concentrations 1988 ± 1989 in Erfurt (Spix et al. 1993).
Fig. 13.
Logarithmic association between TSP and SO2 and total mortality in Erfurt (Spix et al. 1993).
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Fig. 14. Total mortality in Erfurt in association with SO2 and TSP 1980 ± 1989. Comparison of 95 percentile with 5 percentile of the distribution of the pollutants (Spix et al. 1993).
Fig. 15. Premature deaths due to high pollution with a lag of 15 days. Comparison of 95 percentile and 5 percentile of the distribution of the pollutants (Spix et al. 1993).
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Fig. 16.
Theoretical increase of total mortality during the smog episode 1985 in the Rhine-Ruhr-area and Erfurt (Spix et al. 1993).
Fig. 17. 1993).
Theoretical and observed increase in total mortality during the smog episode 1985 in the Rhine Ruhr area and Erfurt (Spix et al.
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Table 4. Smog episode 1985 in Augsburg (Southern Germany).
Winter 84/85 (without episode) Air pollution episode Winter 87/88
SO2 [mg/m3]
TSP [mg/m3]
48.1 (13 to 103) 200.3 (160 to 238) 23.6 (6 to 71)
47.4 (7 to 135) 97.7 (62 to 176) 48.3 (12 to 134)
Table 5. Increase in plasma viscosity and C reactive protein (CRP) in participants* of the MONICA Study Augsburg during the smog episode 1985 (from Peters et al. 1997, 1999). Odds Ratios:
Plasma viscosity > 90th percentile
95% CI
CRP > 90th percentile
95% CI
Episode SO2 (80 mg/m3) TSP (90 mg/m3)
1.99 1.39 1.65
1.10 to 3.60 0.92 to 2.09 0.81 to 3.40
3.57** 1.80 2.31
0.68 to 18.7 1.09 to 2.96 1.29 to 4.13
* 631 men aged 45 to 64; ** adjusted for TSP
Table 6. Increase of heart rate and blood pressure in participants of the MONICA Study Augsburg during the smog episode 1985 (from Peters et al. 1997, 1999).
Episode SO2 (80 mg/m3) TSP (90 mg/m3)
Change in Heart Rate [bpm]
95% CI
Change in Systolic Blood Pressure [mmHg]
1.79 1.04 1.56
0.72 to 2.87 0.60 to 1.49 0.68 to 2.43
0.19 0.70 1.78
and 3600 mg/m3. The daily maxima for TSP were 650 in 1988 and 618 mg/m3 in 1989. There was a logarithmic rather than a linear exposure response relationship for SO2 and TSP (Figure 13), and the association of mortality with TSP was stronger than with SO2 (Figure 14). Furthermore, there was a clear indication of premature mortality. High mortality two weeks before led to a smaller effect of air pollution than low mortality two weeks before. This ªharvesting effectº was much stronger for TSP than for SO2 (Figure 15). Two pollutant models including SO2 and TSP could only be applied since 1988. The calculations showed that the parameter for SO2 was reduced to close to zero while the parameter for TSP only decreased slightly (Spix et al. 1993). We also tried to understand why there was a strong effect on daily mortality in the Ruhr area with SO2 concentrations below 1000 mg/m3, whereas there was nearly no effect in Erfurt with SO2 concentrations of more than 3000 mg/m3. This surprising result could be explained by the logarithmic form of the exposure response relationship. Since in the Rhine-Ruhr area both the concentration of SO2 and
95% CI
1.27 to 1.66 0.09 to 1.30 0.67 to 2.88
mortality were low before the episode, an increase of mortality by 8% easily can be understood (Figures 16, 17). However, in Erfurt both the SO2 concentration and mortality were already very high before the episode, and the episode itself could only add a small effect. The model calculation (Figure 16) resulted in a theoretical increase in mortality by about 2% which could not be identified empirically for statistical reasons.
Augsburg (Southern Germany) By chance during the 1985 smog period a health survey was performed in Augsburg, Southern Germany within the MONICA (monitoring of determinants of cardiovascular diseases) project of WHO. Although air pollution was moderate (highest daily mean of TSP was 100 mg/m3, and of SO2 it was 200 mg/m3, Table 4), this was a unique opportunity to analyze smog effects on sensitive cardiovascular parameters, which were prospectively collected.
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Table 7. Comparison of pollution and daily mortality during four episodes 1962-1985 in the Rhine-Ruhr-area (from Wichmann et al. 1989). Episode (duration)
Dec. 1962 (5 days)
SO2 [mg/m3] 30-min value 3-hr value 24-hr value
5.0
TSP [mg/m ] 3-hr value 24-hr value
2.4
Jan. 1979 (1 day)
Jan. 1982 (6 days)
Jan. 1985 (5 days)
1.4 1.1 0.6
1.1 0.9 0.6
2.2 1.6 0.8
0.5
0.6 0.5
0.8 0.6
none
none
8%
3
Increase of total mortality
Fig. 18.
19%
Increase in total mortality during the smog episode of 1962 (Steiger and Brockhaus et al. 1971).
During the episode, the distribution of plasma viscosity and C-reactive protein (CRP) measured in the study participants in Augsburg were shifted to the right. For plasma viscosity above the 90th percentile, the OR increased significantly to 1.99 and for CRP to 3.57 (Table 5). The heart rate increased significantly by 1.8 beats per minute and the blood pressure also increased slightly (Table 6). The voltage at the ST segment pointed towards a systemic reaction which might precipitate ischemic events. When SO2 and TSP were compared, TSP showed stronger associations for all health endpoints (Peters et al. 1997, 1999a and b).
Earlier smog episodes (1962, 1979, 1982) The episode with the highest ambient concentrations in Central Europe occurred in December 1962. It lasted for five days. In the Rhine-Ruhr-area the pollutants reached daily means of 5000 mg/m3 SO2 and 2400 mg/m3 TSP (Table 7). During this episode the number of deaths increased significantly in the week from the beginning of the smog compared to the control period (Steiger and Brockhaus 1971, Figure 18). While the daily mortality at the Ruhr
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Fig. 19.
Increase of total mortality by area during the smog episode of 1962 in Northrhine Westfalia (Steiger and Brockhaus 1971).
Fig. 20.
Increase of total mortality by area during the smog episode 1985 in Northrhine Westfalia (Wichmann et al. 1989).
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increased by 19%, there was an increase by 25% in the city of Köln and nearly no change in the rural parts of Northrhine Westfalia (Figure 19). This pattern was very similar to that of the 1985 episode (Figure 20). It should be noted, that during the same episode in December 1962 in London air pollution also was high, followed by an increase of mortality by 20%, corresponding to 340 additional deaths (Scott 1963). In 1979 during a one day smog episode concentrations of 600 mg/m3 SO2 and 500 mg/m3 TSP (3 hours average) were reached, but no increase of mortality could be found (Steiger 1980, Table 7). In 1982, a local smog episode of 6 days was reported in the center of the Ruhr area where 600 mg/ m3 SO2 and 500 mg/m3 TSP (24 hours averages) and also high concentrations of NO2 and CO were reached (Külske 1982). The analyses of the mortality data of this small area did not show an observable effect (Wichmann et. al.1989, Table 7). During this episode, also a mortality analysis was performed in West-Berlin (Borgers und Heberling 1982). The authors also did not find an effect on mortality. In Berlin the maximum SO2 concentration was 864 mg/ m3 and the maximum TSP concentration 395 mg/m3 (24 hour averages). The episode lasted from January 11 to 22, 1982.
Discussion Compared to the smog episodes in London, smaller (but nevertheless important) episodes occurred in Central Europe. In December 1952, no elevated air pollution had been reported for Germany, probably due to the fact that the industry was destroyed after the war and no source of air pollution comparable to London was available. Furthermore, no ambient measurements were performed. This was different at the beginning of the 1960s when the German industry had been reestablished. Therefore, the episode of 1962 occurred both in London and at the Ruhr with comparable effects. Several smaller episodes were observed in the 1970s and 1980s, until 1985 the last big episode occurred in Central Europe. Interestingly, the effects observed in the region with the highest pollution, namely Eastern Germany, were only minor. Only mortality data were available there, and these data did not show any effect of the episode. Our interpretation is that the concentration of air pollutants was already very high before the episode so that the additional increase did not lead to further deaths. This might be explained by premature deaths, i.e. frail people
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dying a few days earlier. This phenomenon has been described during the 1980s in Eastern and Western Germany. However, in later years with much lower ambient concentrations it was not observed anymore. Interestingly, as a rule stronger effects were seen for cardiac endpoints compared to respiratory endpoints. In general, patients with existing diseases or reduced health status were at higher risk. Patients with allergy-related diseases like asthma or croup syndrome seemed not to be affected. It is a curiosity, that in an area with relatively low concentrations during the smog episode, namely Augsburg, the most interesting effects were found. This is due to the fact that a large survey was performed at the time when the smog episode occurred. Therefore it was possible to analyze sensitive parameters which were not available at the places of the higher concentrations. In Augsburg, significant effects on plasma viscosity, C-reactive protein and heart rate were observed. Although in the discussed episodes SO2 seemed to be an important pollutant, meanwhile it is clear that SO2 probably was an indicator rather than a causal agent. This is supported by the fact that in two pollutant models already at that time TSP had a stronger influence than SO2. Furthermore, SO2 decreased over the years enormously by a factor of 100 or even more. Nevertheless, even today associations of health endpoints with SO2 are observable (Wichmann et al. 2000). There is no indication that these low concentrations of SO2 can be relevant, based on animal experiments and controlled human exposure. Therefore, SO2 even today seems to be an indicator of a different causal agent, which most probably is related to particles. One also has to keep in mind that TSP from our today knowledge probably is not the most relevant particle metrics. Smaller particles, as measured by PM10 or PM2.5 or the number count of ultrafine particles, which are subgroups of TSP, seem to be more relevant, but these were not measured in earlier years. In total, from these earlier episodes lessons can be learned which are still relevant for today's research: 1) There were more immediate effects on respiratory endpoints (as seen for ambulance transports) and more (by few days) delayed effects on cardiovascular endpoints (as seen for hospital admissions and mortality). 2) Cardiovascular effects were stronger than respiratory effects. 3) In places with high traffic pollution (Köln, Düsseldorf, Augsburg) the effects were stronger
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than in areas with `classical' pollution from industry (Ruhr area) or domestic heating (Erfurt). 4) Particles showed stronger effects than SO2. Today particulate matter is considered to be the most relevant ambient pollutant with respect to health effects - but we think of PM10, PM2.5 and particle number rather than of TSP. Furthermore, interest in epidemiological and toxicological research on particles has been shifted from the lung to the heart and the circulation, and we discuss influences on the autonomous nervous system, inflammatory parameters and translocation of ultrafine particles into the blood stream (Wichmann et al. 2002, WHO 2003). Thus, retrospectively seen, these modern developments are based on the smog history of earlier decades.
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