4. RESULTS OF SUBSYSTEM 1: HEALTH CONSEQUENCES AND RISKS RELATED TO AIR POLLUTION

4.1 Organization of monitoring activities

Subsystem 1 is focused on selected indicators of population health and air quality monitoring. Information on population health status is obtained from general practitioners and pediatricians in out-patient as well as in-patient healthcare facilities (acute respiratory diseases) and from the parents of selected groups of children (allergy and quality of indoor air), namely in part from routine records and in part through questionnaire investigation.

Information on air pollutant concentrations in the ambient air is obtained from the network of manual and automated observation units run by Public Health Centers of the cities monitored and from selected measuring points supervised by the Czech Hydrometeorological Institute (ČHMÚ) which meet the requirements of the Monitoring System.

During 1999, some modifications were materialized to the central database of the subsystem and in the information processing procedures:

4.2 Incidence of acute respiratory diseases

The incidence of acute respiratory diseases (ARO) is an important indicator of population health and occurs most frequently in children. 25 cities were monitored in this regard as in previous years. In 1999, 75 pediatricians and 45 general practitioners providing care to a total of 184 525 patients (97 548 and 88 077, respectively) took part in data collection. When the data collection of 1999 was finished, a five-year temporal series was available, allowing not only the basic data description for the period 1995 - 1999 but also evaluation of the temporal trend and the basic statistical processing.

The mean monthly ARO incidence rates in 1999 in age groups 1 - 5, 6 - 14 and adults (Fig. 4.1a - 4.1c) in most cities monitored are lower than half of the value interval 1994 - 1999. ARO distribution according to age shows the maximum incidence rate in age group 1 - 5 (Fig. 4.1a). Basic data evaluation for the period 1995 - 1999 showed neither positive nor negative correlation in most cities. A negative correlation, i.e. a decrease in the incidence rate in time at least in two age groups simultaneously in a city monitored, was found in Brno, Jablonec n/N and Ústí n/O.

Further statistical data processing was focused on evaluation of the ARO incidence rate in more detail, i.e. on its variation in time and the relationship between morbidity and nitrogen oxides concentration (selected pollutant monitored in all cities where ARO is also monitored), and covered for:

Seven cities with unified statistically significant patterns in time (for both age groups and both groups of diagnoses) were identified. The ARO incidence rate has decreased in time in Mělník, Ústí n/L, Havlíčkův Brod, Brno, Jihlava and Ostrava, and on the contrary has increased in Plzeň. Only two cities, Hradec Králové and Karviná, have showed non-significant changes in time for both age groups and both groups of diagnoses. The remaining cities did not display any unified trend in time either for the age groups or diagnoses monitored. Any statistically significant correlation between ARO morbidity and concentrations of nitrogen oxides was not found in any of the cities monitored, the values showed random distribution.

The ARO incidence rates for 1999 are similar to those of the previous years, ranging from several tens to several hundreds of cases per 1 000 persons of individual age groups according to year season and actual epidemiological situation. Also the distribution of individual groups of diagnoses from the whole spectrum of ARO monitored was similar in 1999 as in the previous years. The most frequent group of ARO in all age categories are inflammations of the upper respiratory airways, accounting for 63 - 76 % of the ARO cases on average. Influenza is the second, 9 - 24 % and bronchitis follows, 5 - 12 %. The order of the remaining diagnoses monitored according to their frequency is as follows: complications of inflammations of the upper respiratory airways (1.8 - 2.2 %), inflammations of the lower respiratory airways (0.5 - 1 %), and asthma (0.2 - 0.6 %).

4.3 Risk factors of serious combined allergic diseases

In 1999, a case control study was conducted, extending the allergy prevalence studies of 1996 and 1997. Its objective was to obtain information on the eventual risk factors possibly involved in the development of serious allergic diseases.

A group of 152 children with combined serious allergic affections (asthma pollinare, dermorespiratory syndrome) were classed in the case group out of 9 947 children from the allergy prevalence studies (Summary report 1997 and 1998). A control group was created from 456 children (3:1) without any symptom of allergy. Three periods were monitored in the child’s life: prenatal period (mother’s pregnancy), neonatal period (up to the 28th day of life) and postnatal period up to 5 years of age (previous investigations showed that more than 53 % of all allergic affections began at this age). The factor with statistically significant differences between the cases and controls, at least at the five percent significance level (logistic regression), are considered to be risk factors (Fig. 4.2). The results are complemented by odds ratio (OR) values, i.e. case to control groups odds ratio (see chapter 11):

It can be summarized that apart from the already known and confirmed factors such as a positive family history and high respiratory morbidity in early childhood (particularly that due to bronchitis), the series of factors influencing the mother during pregnancy and childbirth and thus also her child from the prenatal period was identified. Many factors, which the child encounters during the first years of life, are also significant.

4.4 Hospital admission for acute respiratory diseases

In 1999, statistical analysis of the data from the years 1997 and 1998 was carried out. Descriptive data processing consisted in the distribution of the absolute daily incidence rates into individual groups of diagnoses and in the preparation of daily data on concentrations of major pollutants in ambient air and mean outdoor temperature, weekly information on epidemiological situation in acute respiratory diseases and basic demographic characteristics.

Given the low frequencies of the phenomena studied, Poisson regression for analysis was used, since allowing the modeling of the frequency of morbidity according to its long-term trend (order of the day in the period follow-up), order of day in the week and pollutant concentration. Analyses were carried out for the following items:

The test criterion was whether an increase in air pollutant concentrations is associated with an increased rate of children hospitalized or seeking on-duty medical first aid for acute respiratory diseases follow-up. Nitrogen dioxide (NO2) proved to have a significant effect with a four-day delay with reference to the hospitalized morbidity rate (p < 0.0001) and with a five-day delay with reference to the rate of presentations for first aid service (p = 0.0015). Particulate matter, fraction PM10, concentration was not significantly associated either with the hospitalization rate or with the on-duty medical first aid presentation rate. The delays found seem to be attributable to the incubation period preceding clinical manifestation of the patient’s symptoms, patient’s delay before arriving for ordinary or emergency treatment and administrative delay related to admission to the hospital and its recording.

4.5 Ambient air pollution

In 1999, air pollutant concentrations in ambient air were measured in 27 cities (Tab. 3.1 and Fig. 4.3a - 4.3i). The following modifications were made to the monitoring activities:

In 1999, sulphur dioxide, particulate matter (fraction TSP and/or PM10 fractions), sum of nitrogen oxides and mass concentrations of selected metals (arsenic, chromium, cadmium, lead and nickel) in particulate matter samples were monitored in all cities under follow-up. In some of them, immission concentrations of other metals in particulate matter (beryllium, manganese, copper, mercury and vanadium), carbon oxide, ozone, nitrogen oxide and nitrogen dioxide continue to be monitored selectively.

4.5.1 Pollutants monitored in all cities under the Monitoring System

In 1999, the long-term observed trend in development of some commonly monitored pollutants continued (Fig. 4.4a - 4.4h):

4.5.2 Selectively monitored pollutants

In 1998 the monitoring of polyaromatic hydrocarbons (PAH) in seven cities continued (Prague, Brno, Plzeň, Ústí n/L, Benešov, Karviná and Žďár n/S). For technical reasons the measuring unit in Ústí n/L carried out measuring in the winter season only. Twelve hydrocarbons were followed up (phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene and indeno(c,d)pyrene). These are among the most important from the public health point of view.

From the results (Fig. 4.3i) it is apparent that in Karviná the levels of polyaromatic hydrocarbons reach values four times higher than in other cities under monitoring. This rate is similar with the year 1998. In 1999, the recommended admissible concentration of phenanthrene was not exceeded in any of the cities under follow-up. The maximum recommended admissible value of benzo(a)pyrene was exceeded in all the localities under monitoring. The worst situation is in Karviná where 80 % of the results were higher than 0.001 µg/m3 and the mean annual concentration of this substance is 0.008 µg/m3. In localities least burdened with these contaminants, in Žďár n/S and Brno, decrease in levels of benzo(a)pyrene occurred. The annual mean is 0.0005 µg/m3, i.e. 16 times less than the level in Karviná. In Prague and Plzeň one half of the results exceed the recommended value of the maximum admissible concentration and the annual mean is around 0.0015 µg/m3. The recommended value of the maximum admissible concentration for benzo(a)anthracene was exceeded in Karviná only, where over one third of the samples analyzed exceeded 0.010 µg/m3 (the recommended value of the maximum admissible concentration). In all of the other cities the concentrations of this pollutant has decreased.

The carcinogenic potential of PHAs was expressed by the toxic equivalent (calculated as benzo(a)pyrene). From the results (Fig. 4.3i) it is apparent that in Karviná the carcinogenic potential of polyaromatic hydrocarbons is six times higher that in Prague, Plzeň and Hradec Králové and that the burden in Brno and Žďár n/S is one half of that in Prague.

Regular monitoring of volatile organic compounds (VOC) has been performed since June 1999 in three cities (Prague, Ústí n/L, and Karviná), two other cities joined in October (Hradec Králové and Sokolov). 42 organic compounds were followed up (according to US EPA TO - 14). Among the most important, for which recommended values of maximum admissible concentrations had been set, are aromatic hydrocarbons (benzene, toluene, xylenes, styrene, trimethylbenzenes) and chlorinated aliphatic and aromatic hydrocarbons (trichloromethane, tetrachloromethane, trichloroethene, tetrachloroethene, chlorobenzene, dichlorobenzenes). These recommended values of the compounds followed up were exceeded only exceptionally in the localities under monitoring.

The significance of the substances under follow-up, which may under feasible conditions cause the formation of photochemical reaction products in the atmosphere, i.e. nitrogen monoxide, nitrogen dioxide, ozone and organic substances (Fig. 4.4e - 4.3i and Fig. 4.4e - 4.4h), continues. Analysis of temporal trends confirms a relatively stable level in the majority of residential areas.

4.5.3 Metals in particulate matter

The mass concentration of the metals under long-time monitoring was obtained by analysis of 14-day cumulative samples of particulate matter. Analysis of temporal trends in most cities shows a negative correlation, i.e. decreasing concentrations in time, a positive correlation has not been found in any of the metals under follow-up. The results for individual metals (Fig. 4.5a - 4.5f) can be summarized as follows:

4.6 Exposure assessment of major pollutants

According to values of the annual index of air quality, IKOr (Fig. 4.6), 15 out of 36 evaluated sites and Prague districts belong to the third category (moderately polluted atmosphere) and only one locality, Prague 5, to the fourth category (polluted atmosphere). The other sites under follow-up fall into the second category (acceptable atmosphere). Analysis of the temporal trends confirmed a stable state in the majority of sites under follow-up, a significant decrease in pollution was recorded in Ústí n/O, Most, Havlíčkův Brod, Hradec Králové, Prague 6, Klatovy, and Příbram. On the contrary, a significant increase in pollution was not recorded.

The degree of pollution can also be expressed as the potential exposure of the population of a given locality to a certain concentration level. The mean long-term exposure to major pollutants which have set annual limits is demonstrated in such a manner, and the result reflects the proportion of the total population in cities under monitoring, that is exposed to a certain level of pollutants in the ambient air (Fig. 4.7). The greatest population exposure occurs in the case of particulate matter, fraction TSP or PM10. In the case of nitrogen oxides the situation is stabilized, and regarding sulphur dioxide, its previously discussed decrease is apparent.

4.7 Mobile measuring systems

In the case of the Prague mobile system operated by the NIPH, in 1999 the processing of results obtained in the first phase of measuring continued and the relationship between localities being measured and the existing units of the national immission network was assessed. The second phase of measuring began in the second half of the year. The objective of the measuring was:

In collaboration with the Faculty of Transportation at the Czech Technical University (ČVUT) in Prague, a procedure for the evaluation of immission characteristics of selected compounds, obtained through the NIPH mobile system, in relation to the traffic load has been suggested. With the aid of the “Ordinary kriging” method and linear interpolation, a model for calculating the immission situation in the Prague agglomeration was construed, which upon updating and validization of the monitoring data on concentration levels enable a detailed estimation of the areal immission burden on the basis of measuring by the AIM system in Prague.

Specialists from the Regional Public Health Center in Brno with a mobile system operating there continued in the second phase of measuring within the study and simultaneously participated on other monitoring activities. In extension, the NIPH Prague in collaboration with the Faculty of Natural Sciences, Charles University, prepared a summary information (in the GIS format) on the areal exposure to major pollutants in the Brno locality. The processing procedure is now compatible with that one in the Prague locality. In Fig. 4.8a and 4.8b the results of the graphic treatment of mean values of the major pollutant, NOx, and the ratio NO/NO2 are presented. The ratio NO/NO2 when greater than 1 indicates a greater burden from traffic in the locations measured. Information obtained serves the Public Health Service and organs of the administration and represent the optimum procedure for characterizing the areal immission burden of the Brno inhabitants.

4.8 Quality of the indoor environment

In 1999, following the preparatory stage of 1998 and in extension of the pilot study of 1994 - 1997, a new project “Monitoring of the Indoor Environment” was begun. The time schedule comprises two years and it is being implemented in Brno, Hradec Králové, Ostrava and Ústí n/L. In the first year of the project proper there was conducted a questionnaire survey as a follow-up of acute respiratory morbidity in children attending nursery schools, the measuring of the indoor air in nursery schools and measuring of the quality of indoor air in flats, that will be carried on in the year 2000.

The objective of the questionnaire survey was to describe certain factors of the children’s lifestyle, their health status or health problems that may be related to indoor air quality, i.e. to the home or nursery environment and to the characteristics of the residential site. The response rate was 71.3% and a total of 1 300 respondents from 19 kindergartens participated. The results are described with the aid of frequency analysis for determining the influence of individual factors of the lifestyle and living conditions on health. Logistic regression was used for comparing each factor with that in other cities. An estimate of the child’s time schedule in the course of the day is depicted in Fig. 4.9a and 4.9b for the summer and winter seasons separately.

Of the statistically significant relations found, fore mostly important is the correlation of the occurrence of moulds in flats with the frequency of acute respiratory diseases. The relative risk of the appearance of this affection in homes with moulds is 1.7 times (so-called odds ratio) greater than in homes without moulds. In homes with new furniture made of splinterboard there was found a 1.4 times greater occurrence of complaints in connection with irritation of the nasal mucous membranes than in homes outfitted otherwise. On the other hand there was not confirmed any influence of the outfitting of homes with gas appliances (namely not even in the most unfavorable variant of the simultaneous use of a gas range, gas heating, and gas boiler) on the occurrence of health complaints.

In a single follow-up of symptoms of acute respiratory disease (ARO) or morbidity in children due to ARO (in each city just in one selected nursery in November) there was evaluated the monthly incidence rate of ARO (82.4 cases per 100 children) as well as the number of days of illness in the month under follow-up (on an average 8 days/child).

In each of the cities under monitoring measuring of concentrations of selected pollutants in 15 homes (children’s room and kitchen) was carried out. The homes were randomly selected from among the set of questionnaire respondents who gave consent to the measuring. The measuring is conducted twice in the year, in the heating (November - February) and in the non-heating (May - August) seasons. The following parameters in the homes and kindergartens were followed up:

An analysis of the pollutant level values in the indoor air shall be carried out upon termination of the whole two-year project. From the results of the first year of measuring the set of results from nursery schools can be described as follows:

4.9 Partial conclusions

The 1999 results on the incidence of acute respiratory diseases do not differ significantly from values found in preceding years. Evaluation of the retrospective data from the years 1995 - 1999 in the form of correlation analysis, in the majority of sites, did not reveal any positive or negative dependence of this indicator on time. Evaluation of the set of 20 cities as a whole did not demonstrate any statistically significant relationship between treated morbidity and levels of nitrogen oxides.

In the prevalence of allergic affections in children it can be stated that, except for known and previously confirmed factors such as a positive family history and high respiratory tract morbidity in early childhood (namely bronchitis), there has been demonstrated the significance of several factors that are in play beginning from prenatal life and that influence the mother during pregnancy and childbirth. Significant were several factors the child encounters in the first years of life.

Concerning hospital admission for respiratory affections there has been modeled the intensity of incidence of morbidity from the points of view of the long-term temporal trend (day in the period of follow-up), weekly periodicity (day in the week) and each contaminant (the possible delay of effect of contaminant was also taken into consideration). Significant proved to be the influence of nitrogen dioxide with a 4-day delay in hospitalized morbidity and a 5-day delay in seeking on-duty medical first aid. The influence of PM10 did not prove to be significant.

The mean annual concentrations of sulphur dioxide did not exceeded the value of 20 µg/m3, i.e. 1/3 of the immission limit at any site. Pollution with nitrogen oxides vacillates around the limit value, which it exceeds in two locations under follow-up. An analysis of trends reveals a stable state in the majority of sites. There persists a higher burden of carbon monoxide in the ambient air of the Prague agglomeration. Significant are also pollution levels of particulate matter, fractions TSP and PM10. No value of the annual arithmetical mean of the metals under follow-up exceeded the set or recommended values of immission limits in the cities under monitoring.

Among polyaromatic hydrocarbons, benzo(a)pyrene has been revealed to be an important pollutant (the greatest pollution in Prague, Plzeň and Karviná). The carcinogenic potential of polyaromatic hydrocarbons (toxic equivalent of benzo(a)pyrene) in Karviná is six times greater than in Prague, Plzeň and Hradec Králové. On the other hand, the carcinogenic PAH burden in Brno and Žďár n/S is one half of that in Prague.

The annual index of air quality, IKOr, remains relatively stable in the sphere of the cities under monitoring (a significant fall in values in 7 out of 36 evaluated sites and Prague districts). Potential exposure to concentrations exceeding values of applied exposure limits was found in 1.7 % of the population under follow-up in the case of the sum of nitrogen oxides, where in after a marked deterioration between 1994 and 1995, exposure levels are stable in the years that followed. The population is exposed to the highest mean concentration levels (indiscriminately) in the case of particulate matter, as regards fraction TSP, 63.7 % of the population are exposed to concentrations in the range of 2/3 IHr to 1 IHr.

The first year of the new project “Quality of the Indoor Environment” has been concluded. Information was obtained on the lifestyle of children attending kindergartens, as well as preliminary results of measuring of concentration levels of selected pollutants in nurseries and in the respondents’ homes. Summary results shall be presented only on finalization of the whole two-year project.

Fig. 4.1a Acute respiratory diseases without influenza, children 1 - 5 years, 1995 - 1999
Fig. 4.1b Acute respiratory diseases without influenza, children 6 - 14 years, 1995 - 1999
Fig. 4.1c Acute respiratory diseases without influenza, adults, 1995 - 1999
Fig. 4.2 Risk factors of combined serious alergic diseases, 1999
Fig. 4.3a Sulphur dioxide immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3b Particulate matter immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3c Particulate matter immission, PM10 fraction, 1999 - annual arithmetic mean, daily immission
Fig. 4.3d Nitrogen oxides immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3e Nitrogen monoxide immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3f Nitrogen dioxide immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3g Carbon monoxide immission, 1999 - annual arithmetic mean, daily immission
Fig. 4.3h Ozone immission, 1999 - annual arithmetic mean, 95% quantile of daily concentration
Fig. 4.3i Polyaromatic hydrocarbons immission (PAH), 1999 - annual arithmetic mean (UL measurements in winter only)
Fig. 4.4a Evaluation of sulphur dioxide immission - annual arithmetic mean, 1991 - 1999
Fig. 4.4b Evaluation of particulate matter immission - annual arithmetic mean, 1991 - 1999
Fig. 4.4c Evaluation of particulate matter immission, fraction PM10 - annual arithmetic mean, 1995 - 1999
Fig. 4.4d Evaluation of nitrogen oxides immission - annual arithmetic mean, 1991 - 1999
Fig. 4.4e Evaluation of nitrogen monoxide immission - annual arithmetic mean, 1994 - 1999
Fig. 4.4f Evaluation of nitrogen dioxide immission - annual arithmetic mean, 1994 - 1999
Fig. 4.4g Evaluation of carbon monoxide immission - annual arithmetic mean, 1994 - 1999
Fig. 4.4h Evaluation of ozone immission - annual arithmetic mean, 1994 - 1999
Fig. 4.5a Arsenic in particulate matter - annual arithmetic mean, 1991 - 1999
Fig. 4.5b Cadmium in particulate matter - annual arithmetic mean, 1991 - 1999
Fig. 4.5c Chromium in particulate matter - annual arithmetic mean, 1991 - 1999
Fig. 4.5d Nickel in particulate matter - annual arithmetic mean, 1991 - 1999
Fig. 4.5e Lead in particulate matter - annual arithmetic mean, 1991 - 1999
Fig. 4.6 Annual index of air quality (IKOr), 1995 - 1999
Fig. 4.7 Exposure to major pollutants from ambient air, 1994 - 1999
Fig. 4.8a Average values of nitrogen oxides immission in Brno evaluation from July 1994 to February 1996
Fig. 4.8b Quotient of average values of NO/NO2 concentrations in Brno evaluation from July 1994 to February 1996
Fig. 4.9a Time frame of day in summer for child resorting kindergarten
Fig. 4.9b Time frame of day in winter for child resorting kindergarten

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