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

4.1 Organization of monitoring activities

The Subsystem is intended for monitoring selected indicators of population health and air quality. Information on population health status is obtained from general practitioners and pediatricians in out-patient facilities.

Information on ambient air pollutant concentrations is obtained from the network of manual and automated units operated by the Public Health Centres of the cities monitored and from selected measuring facilities supervised by the Czech Hydrometeorological Institute, the location of which meet the requirements of the Monitoring System.

4.2 Incidence of treated acute respiratory diseases

Acute respiratory diseases (ARD) account for the highest percentage of morbidity in children (particularly in preschool children) and therefore the ARD incidence is used as an important indicator of population health.

The ARD monitoring database MONARO provides information on ARD morbidity and its development in both children and adult population. This database is a self-contained system based on continual collection, processing and evaluation of data on ARD morbidity obtained from general practitioners and pediatricians. The source of information are medical records on the first treatment given to patients presenting with acute respiratory disease. The basic outputs are absolute numbers of new cases of selected diagnoses in the population monitored and their incidence rates in different age groups, i.e. rates of new cases of a given disease per 1000 population or population group monitored.

In 2001, 75 pediatricians and 45 general practitioners providing care to a total of 182 292 patients in 25 cities took part in ARD data collection. The central database is being regularly validated to clear possible redundant or incorrect records.

The data of 2001 do not markedly differ from those of previous years. Fig. 4.1a and 4.1b show the highest, lowest and mean monthly ARD incidence rates of 2001 and the range of the mean monthly ARD incidence rates for 1995–2001. The mean monthly ARD incidence rates recorded in 2001 in children aged from 1 to 14 years were mostly close to the lower limit of the mean values range in previous years (with the exception of Plzeň, Liberec, Hodonín, Karviná and Havlíčkův Brod).

The monthly incidence rates of ARD (excluding influenza) per 1 000 children of the same age group varied widely in children up to 18 years from 2 (Benešov) to 500 (Plzeň). As in previous years, the highest morbidity was recorded in the age group 1 to 5 years. In most cities, the ARD morbidity shows seasonality with a typical downward tendency in summer.

As in the year 2000, lower respiratory tract morbidity including pneumonia, which is likely to be responsive to air pollution diseases, was monitored. The monthly incidence rates of this morbidity in children aged up to 18 years range from 0 in summer months (Ústí nad Labem, Havlíčkův Brod, Hradec Králové) to 125 (Plzeň in December) per 1000 population of the same age group. The highest morbidity of Plzeň is due to a higher incidence of pneumonia, particularly in children aged 1 to 5 years. In this age group, bronchitis and pneumonia account for the highest percentage of the general ARD morbidity, ranging from 24 % in Svitavy to 6 % in Liberec.

As in previous years, the most frequent ARD for all age categories and monitored cities is the diagnoses group diseases of the upper respiratory tract, accounting annually for 73 % of the ARD morbidity on average. Influenza was the second (15 %) and inflammation of the lower respiratory tract follows (9.3 %). The order of the remaining diagnoses monitored according to their frequency is as follows: otitis media – rhinosinusitis – mastoiditis (1.8 %), pneumonia (0.8 %), and asthma (0.3 %).

4.3 Prevalence of allergic diseases in children

In 2001, the prevalence rates of allergic diseases in the population of 5, 9, 13 and 17-year-olds were investigated in 18 cities. The 1996 questionnaire was used with additional questions related to the pre- and peri-natal periods. The data were obtained from medical records of 54 pediatricians and from parents during the obligatory preventive check-ups. The main objective was to obtain data on the prevalence of allergic diseases in children and to compare them with those of 1996. In the following year, the data will be analyzed from the point of view of risk factors possibly involved in development of allergic diseases. A total of 7850 children, 51 % males, was investigated. The questionnaire returnability was 93 %.

The results were described using frequency analysis and the hypothesis of congruence between the percentages of the categories in the contingency table was assessed by the test of independence c2. The exposure/effect linkage is described by the odds ratio (OR) between the population exposed to a factor and that non-exposed. The OR values are adjusted for gender, age, city and family history. The tests were performed at the 0.05 significance level. The P values are indicated as follows: * p < 0.05, ** p < 0.01, *** p < 0.001.

4.3.1 Prevalence of allergic diseases in children in 2001

Allergic diseases diagnosed by pediatricians were recorded in 1935 out of 7850 children followed up, which means a prevalence rate of 24.7 %. A significantly higher prevalence of allergic diseases was found in boys (26.4 %***) compared to girls (22.8 %). Boys suffered more frequently from asthma (OR = 1.6***), relapsing obstructive bronchitis (OR = 1.4*) and pollinosis (OR = 1.4***). Girls were more frequently afflicted with atopic eczema (OR = 1.2*). Differences between boys and girls were not recorded for non-pollen rhinitis and the other allergies. Distribution of diagnoses in all subjects studied and allergic children is presented in Table 4.1 and Fig. 4.2a, respectively.

Table 4.1: Distribution of allergy diagnoses in children

Single allergy diagnoses

n

%

Allergic pollen rhinitis (pollinosis)

867

11.1

Atopic dermatitis

554

7.1

Asthma

399

5.1

Relapsing obstructive bronchitis

227

2.9

Other allergic rhinitis

97

1.2

Other allergies

327

4.2

Multiple allergy diagnoses

n

%

Pollinosis + atopic eczema

129

1.7

Asthma pollinare

116

1.5

Dermorespiratory syndrome

93

1.2

Dermorespiratory syndrome + pollinosis

30

0.4

As many as 40 % of the children followed up had allergy in family history, 61 % of the allergic children indicated allergy in parents or siblings. The risk of developing allergy was almost three times higher in children with allergy in family history (OR = 2.9***) compared to those without allergy in family history.

Four age groups of children (5-, 9-, 13- and 17-year-olds) were followed up to consider the dynamics and age distribution of each of diagnoses. The allergy prevalence in 5-year-olds was 21 %. It showed a statistically significant rise to 24 % between the fifth and ninth year of age (OR = 1.3***). Up to 17 years of age, it continued to show a further increase, but not statistically significant (27 % in 13-year olds and 28 % in 17-year-olds). The asthma prevalence increases most between the fifth and ninth year of age (OR = 1.5*) to remain unchanged later. The highest prevalence of atopic eczema was found in 9-year-olds while the 17-year-olds show statistically significant decrease in this morbidity (OR – 0.8*). Pollinosis shows the prevalence rates increasing statistically significantly with age (OR = 4.6*** in 17-year-olds compared to 5-year-olds). Relapsing obstructive bronchitis has also been listed among allergy diagnoses since preceding development of asthma. Such bronchitis was most frequent in nine-year-olds, its prevalence decreasing with age; the decrease was statistically significant in 17-year-olds (OR = 0.5**). This is explainable by the fact that this diagnosis is likely to change into asthma or other allergic disease with age.

Non-pollen allergic rhinitis and the other allergies did not show any age-associated variability. The age distribution of allergic diseases is shown in Fig. 4.2b.

4.3.2 Prevalence of allergic diseases in children of selected cities

Eighteen cities varying in size (from 15 000 to 385 000 population + Prague) and outdoor air quality were selected to obtain representative data on the prevalence of allergic diseases in children. The allergy prevalence rates in these cities ranged from 11 % to 42 %. The lowest allergy prevalence rates were found in Ústí nad Orlicí (11 %), Olomouc (13 %) and Kladno (14 %). The most afflicted cities in this regard were Jablonec nad Nisou (42 %), Žďár nad Sázavou (37 %) and Sokolov (35 %). Prague, Brno and Ostrava showed allergy prevalence rates of 31 %, 21 % and 20 %, respectively. Distribution of different diagnoses in each of the cities is represented in Figure 4.2c.

To assess possible effect of the outdoor air quality on the prevalence of allergic diseases, frequently described in the literature, a general indicator was used – the annual Air Quality Index (AQI). Based on this indicator, available for each of the cities for the period 1995–2000, the cities were divided into three groups. Group 1 included the cities with an annual AQI geometric mean ranging between 1.0 and 2.0 and a maximum lower than 3.0 (clean, acceptable atmosphere, resp.). Group 3 covered the cities with worst air quality, i.e. an annual AQI geometric mean ranging between 2.5 and 3.0 and at least triple maximum over 3.0 (polluted air, posing risk to sensitive population). The remaining cities were placed in group 2. Group 1 showed the lowest percentage of allergic children (22 %) while the highest percentage of allergic children was found in group 3 (27 %**), the difference being statistically significant.

4.3.3 Comparison of the prevalence rates of allergies in children in 1996 and 2001

One of the study objectives was to compare the allergy prevalence found in 2001 with that of 1996. The same methods were used and the same physicians took part in the study in both years. The allergy prevalence rates were compared for 5-, 9- and 13-year-olds (the 17-year-olds were not included in the study of 1996). The total percentage of allergic children increased by about one half in 2001 compared to 1996 (23.4*** and 16.9 %, respectively), the differences being statistically significant for all three age groups (Fig. 4.2d). All diagnoses monitored became more frequent compared to 1996 (Figure 4.2e). The percentages of allergic children increased statistically significantly in six of 16 cities compared (Fig. 4.2f).

4.4 Air pollution in the cities

In 2001, air pollutant concentrations were measured in 75 stations (49 and 26 operated by the Ministry of Health and the Ministry of the Environment, respectively) of 27 cities included in the Monitoring System (Table 3.1 and Fig. 3.1). In 2001, sulphur dioxide (manual stations performed measurements during the heating season only), sum of nitrogen oxides, particulate matter (TSP and/or PM10 fraction), and mass concentrations of selected metals (arsenic, chromium, cadmium, manganese, nickel and lead) in particulate matter samples were monitored in all cities of the Monitoring System. Concentrations of PAHs, volatile organic substances, some other metals (beryllium, copper, mercury, vanadium and zinc) in particulate matter, carbon oxide, ozone, nitrogen monoxide and nitrogen dioxide continue to be monitored selectively.

The concentration limits effective in 2001 were used in valuation of the concentrations as actually measured and/or calculated for each substance monitored.

4.4.1 Pollutants monitored in all cities of the Monitoring System

In 2001, the long-term trend in development of some current monitored pollutants continued.

4.4.2 Selectively monitored pollutants

Polycyclic aromatic hydrocarbons

In 2001, the monitoring of polycyclic aromatic hydrocarbons (PAHs) continued in seven cities (Prague, Brno, Plzeň, Ústí nad Labem, Hradec Králové, Karviná and Žďár nad Sázavou). The following polycyclic aromatic hydrocarbons were monitored according to US EPA TO-13: phenanthrene (maximum admissible concentration MAC = 1000 ng/m3), anthracene, fluoranthene, pyrene, benzo[a]anthracene (MAC = 10 ng/m3), chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene (MAC = 1 ng/m3), dibenzo[a,h]anthracene, benzo[g,h,i]perylene and indeno[c,d]pyrene). The data obtained within the monitoring of the Ostrava – Karviná region on 8 selected PAHs only have also been included in the database. The ambient air sampling was performed every 6th day.

The PAHs include several compounds varying in their health significance. Polyaromates considered as probable carcinogens differ in their health effects as well. Based on comparison of carcinogenic effects of the concentrations measured for different PAHs with that of benzo[a]pyrene as one of the most toxic and best studied carcinogenic polycyclic aromatic compounds, the carcinogenic potential of PAHs in air can be expressed using the benzo[a]pyrene toxic equivalent (TEQ). The following toxic equivalent factors (TEF) given by the US EPA were used for calculation of TEQ:

PAH

TEF

PAH

TEF

PAH

TEF

Benzo[a]pyrene

1

Benzo[b]fluoranthene

0.1

Dibenzo[a,h]anthracene

1

Benzo[k]fluoranthene

0.01

Benzo[a]anthracene

0.1

Indeno[c,d]pyrene

0.1

The concentration of each PAH identified in the mixture is multiplied by the respective TEF and the sum of all products obtained is the TEQ of the PAH mixture studied. The TEQ values for the localities monitored are given in Fig. 4.6a. The highest carcinogenic risk from PAHs was recorded in Ostrava (annual mean of 10.1 ng/m3) and Karviná (annual mean of 8.7 ng/m3). Prague and Plzeň showed a three times lower carcinogenic risk from PAHs compared to Ostrava, Ústí nad Labem and Hradec Králové were at a five times lower carcinogenic risk from PAHs compared to Ostrava.

The PAHs in air have been systematically monitored since 1997 and thus, the results obtained within a five-year period could be statistically analyzed. Benešov, Hradec Králové, Ústí nad Labem and Ostrava were excluded from statistical analysis due to not meeting the requirements for statistical processing. The time series of data on benzo[a]anthracene, benzo[a]pyrene, PAH sum and TEQ values (1997 to 2001) analyzed for five localities (Prague 10, Karviná, Brno, Plzeň and Žďár nad Sázavou) showed complicated non-linear trends that cannot be described unambiguously as decreasing or increasing. This is evident from Fig. 4.6b representing annual TEQ values. In most cities, the curve goes down first to reach the minimum (as in Prague 10 and Plzeň in 1999 and in Žďár nad Sázavou and Brno in 2000) and then shows an upward tendency. The Karviná curve develops in just the opposite way, peaking in 1999. The difference in trends between Karviná and the other cities was confirmed by statistical analysis. This analysis also confirmed differences in the concentrations of PAHs (BaA, BaP, total PAHs and TEQ) between different years and heating and non-heating seasons. The TEQ values obtained in the cities with the lowest burdens (Brno and Žďár nad Sázavou) did not show significant differences while those obtained in the other cities did.

Seasonal changes in the PAH concentrations were analyzed in a more detailed manner. As is evident from Fig. 4.6c representing the TEQ development within 1997–2001, the PAH summer concentrations are by one order of magnitude lower compared to the winter ones. This is consistent with the published data assuming that the winter increase in PAH concentrations is associated with combustion of fossil fuels, poorer dispersion and photolytic degradation of PAHs in ambient air in winter. The curves representing the seasonality effect have comparable forms in all cities analyzed except for Karviná. They show a typical marked summer minimum (June to August) preceded by a progressive decrease in spring and followed by a sharp rise in autumn. Both the high PAH emissions found year-round and a shorter summer minimum in Karviná are likely to be associated with a different structure of industrial sources in that region.

Within statistical analysis, the relationship between the concentrations of benzo[a]anthracene and benzo[a]pyrene was tested. A close interdependence was found for all the cities analyzed, the correlation coefficient varied between 0.64 (Brno) and 0.99 (Karviná).

Volatile organic compounds

In 2001, year-round monitoring of volatile organic compounds (VOCs) was performed in five cities (Prague, Ústí nad Labem, Karviná, Hradec Králové and Sokolov). The ambient air sampling was carried out on the same days as that for PAHs, i.e. every twelfth day from April to September. Forty-two organic compounds were followed up (according to US EPA TO-14); nevertheless, 23 of them only were taken into account in the assessment since the remaining ones were present at concentrations falling below the respective detection limits. The measuring data of Ostrava, using another method to monitor 8 selected VOCs, were also included in the database. Among the most important VOCs, for which recommended maximum admissible concentrations had been set, are aromatic hydrocarbons (benzene, toluene, sum of xylenes, styrene, sum of trimethylbenzenes) and chlorinated aliphatic and aromatic hydrocarbons (trichloromethane, tetrachloromethane, trichloroethene, tetrachloroethene, chlorobenzene, sum of dichlorobenzenes). These recommended limit concentrations were exceeded only exceptionally in the localities monitored. Almost one tenth of the results on benzene recorded in Ostrava exceeded the recommended limit. It is apparent from Fig. 4.6e that the highest burden from total VOCs (sum of VOCs) was found in Ústí nad Labem (167 µg/m3), being five times higher than those in the other localities monitored. High Freon 12 concentrations found in Ústí nad Labem in spring and summer, attributable to possible leakage from e.g. an air-condition unit of the hospital near the sampling device, are to be blamed in this regard.

The monitoring of the substances, which, under opportune conditions, may be responsible for the formation of photochemical reaction products in the atmosphere, i.e. nitrogen monoxide, nitrogen dioxide, ozone and organic substances (Fig. 4.3i to 4.3l, 4.3o and 4.3p), continues to be of concern.

4.4.3 Metals in particulate matter

The mass concentrations of selected metals were obtained by analyses of 14-day cumulative samples of particulate matter. Air pollution by the elements monitored between 1995 and 2001 either shows a slightly downward tendency (lead, arsenic) or is rather stable (cadmium, chromium) without any significant fluctuations (except for nickel).

Fig. 4.7a to 4.7c give information on this air pollutant in unities of lifetime carcinogenic risk (UCR) as indicated by the WHO for two different levels of theoretical estimation of probable increase in risk to population of developing cancer (1x10-6 and 1x10-5) if exposed long-life to the given concentrations of metals in air. Analysis of the metal concentrations measured must also to be based on consideration of probable frequency of such exposures (a conservative scenario, supposing that air shows the same concentrations of the metal studied both indoors and outdoors, is used for this purpose).

The annual mean concentrations of the metals monitored in particulate matter can be described as follows:

4.5 Assessment of exposure to major pollutants

4.5.1 Air Quality Index

The Air Quality Index (AQI) was based on the recorded annual arithmetic means of concentrations of SO2, NOx, TSP and PM10 (Fig. 4.4). Seventeen out of 35 localities and Prague districts monitored showed moderate air pollution (class 3), with Prague 5 (2.882) and Prague 8 (2.907) close to class 4 (polluted air), Prague 7 being monitored for TSP concentrations only. The air quality was satisfactory in other cities (class 2) being best in Kladno and Příbram (class 1 – unpolluted air). Twenty-two localities showed a slight increase in AQI compared to that of 2000.

4.5.2 Exposure to pollutants from ambient air

The degree of air pollution can also be expressed as the potential exposure of the population of a given locality to a certain pollutant concentration level. The mean long-term exposure to major pollutants, the annual limits (IHr) for which are set, is characterized in such a manner. The result reflects the proportion of the total population of a monitored city that is exposed to a certain concentration level of pollutants in ambient air (Fig. 4.5).

4.6 Mobile measuring system operated by the NIPH

In 2001, the data files obtained in the first phase of the mobile system operation (1994 to 1996) continued to be updated. Measurements were performed in twenty localities. Relationships between the first-phase data files and those updated in 2001 were tested by statistical analysis. The objectives were as follows:

The data tested showed significant differences between 1995 and 2001 in nitrogen oxide, ozone and sulphur dioxide levels that can be described as decreases. The data tested did not show any statistically significant shift in mean levels of carbon oxide, the sum of nitrogen oxides (NOx) and nitrogen monoxide (NO) to nitrogen dioxide (NO2) ratio between 1995 and 2001, the trend estimate being rather suggestive of decreases.

The data analysis was mostly complicated (except for SO2 and NO/NO2 ratio) by different variation in pollutant levels found for particular measuring points.

The mobile system of the National Institute of Public Health was audited by the Czech Institute for Accreditation in December 2001 according to ISO 45 000 for measurement of concentrations of sulphur dioxide, carbon monoxide, ozone, TSP and PM10, nitrogen monoxide, nitrogen dioxide and some meteorologic parameters of ambient air quality (pressure, temperature, relative humidity). The mobile system activities were also focused on good operation of the QA/QC system, namely on the transmission of the correct data to the measuring network operated by the Public Health Service in different regions. These activities are parallel to those of the calibration laboratory of the National Institute of Public Health.

4.7 Indoor air quality monitoring

Based on measuring and questionnaire data obtained between 1999 and 2001 for selected dwellings and nursery schools, the screening evaluation of pollution burden by selected airborne pollutants (formaldehyde, benzene, nitrogen dioxide) from indoor and outdoor air was carried out. The basis for the evaluation was indoor concentration levels of these contaminants and a daily timetable of the children set under follow up. It showed that a child spends daily, on average (including weekend days), 15.3 hours indoors at home (ranging from 14.3 hours in summer to 16.1 hours in winter), 3 hours indoors at nursery school (ranging between 2.6 hours in summer and 4 hours in winter) and 5.7 hours outdoors (ranging from 4 hours in winter to 7.2 hours in summer). This means that a child stays indoors at home 5.5 times longer than indoors at nursery school and 2.7 times longer indoors at home than outdoors.

The mean concentrations of formaldehyde in indoor air of all dwellings measured varied between 20 and 30 µg/m3 and 13 to 18 % of the values obtained exceeded 50 µg/m3. Formaldehyde concentrations are not routinely measured in outdoor air; based on the literature data and some targeted measurements, they are expected to reach units of micrograms. It is apparent that the main source of exposure to formaldehyde indoor air. Concentrations exceeding 100 µg/m3 causing significant rise in the incidence of irritating effects on the eye and respiratory tract were found in 4 % of the dwellings monitored.

The mean concentrations of benzene in indoor air ranged between 2 and 4 µg/m3 (median concentrations) and between 5 and 6 µg/m3 (arithmetic mean), 10 % of the values exceeded 10 µg/m3, reaching up to tens of µg/m3 in isolated cases. The mean concentrations in urban outdoor air range between 2 and 4 µg/m3 (arithmetic mean). Indoor exposure to benzene seems to be more significant than that from outdoor in terms of exposure duration as well as higher levels of pollution in some measure. The difference is not as marked as that for formaldehyde. The major indoor source of benzene is tobacco smoke but its effect could not be quantified since the study was focused on preschool children. According to the questionnaire data, smoking was reported in 23 % of the households monitored but remained unreflected in the results obtained.

The mean concentrations of nitrogen dioxide in indoor air of the dwellings monitored ranged between 24 and 25 µg/m3. The mean annual concentrations in outdoor air were lower in 14 localities and higher in 15 localities, ranging between 16 and 41 µg/m3. Therefore, the population is exposed from both indoor and outdoor air in proportions that may vary with localities.

As a concrete application of these findings, exposure to nitrogen dioxide from outdoor and indoor air was compared for the dwellings set measured. Data obtained with the mobile measuring system within two years1 were used to estimate the mean concentration of nitrogen dioxide in outdoor air of a locality covering both dwellings and nursery schools monitored. The results were statistically analysed and represented as areas characterized by concentration intervals in GIS layers (Fig. 4.8).

Data on concentrations of nitrogen dioxide in indoor air were obtained by three-hour interval measurements in both heating and non-heating seasons (1999 to 2001) in 33 dwellings and five nursery schools.

1 Methods and procedures used by the mobile measuring system in Brno are given in detail in the “Special Report of Subsystem I 1999”, 2000.

Based on projection of the addresses of the dwellings measured on an isoconcentration map, the following conclusions were drawn:

1. Mean concentrations of nitrogen dioxide in 13 dwellings (39.4 %) and 3 nursery schools were significantly higher than those resulting from an disperse model;
2. Mean concentrations of nitrogen dioxide in 13 dwellings (39.4 %) and 2 nursery schools were comparable with those resulting from an disperse model;
3. Mean concentrations of nitrogen dioxide in 7 dwellings (21.2 %) were lower than those resulting from an disperse model.

In 80 % of the dwellings and in all nursery schools of this part of Brno, children are exposed to higher concentrations of nitrogen dioxide from indoor air compared to outdoor air. The time spent outdoors and indoors is also to be taken into account in exposure assessment.

4.8 Partial conclusions

The incidence rate of treated acute respiratory diseases (ARD) is similar as in previous years. The monthly ARD incidence rate varied widely from units to hundreds of cases per 1000 population of the given age group. Upper respiratory tract infections were the most frequent (73 %) among the ARD monitored. Lower respiratory tract infections (bronchitis, pneumonia) account for different proportions of the total ARD morbidity rates in different cities. They are most frequent in the age group 1 to 5 years, varying from 6 % in Liberec to 24 % in Svitavy.

In 2001, the incidence of allergic diseases was investigated in 5-, 9-, 13- and 17-year-olds of 18 cities. Allergic diseases were found in medical records of 25 % of children, being more frequent in boys (26 %) than in girls (23 %). The most frequent diagnoses were as follows: pollinosis (11 % of children), atopic eczema (7 %) and asthma (5 %). The incidence rates of allergic diseases increased with age from 21 % in 5-year-olds to 28 % in 17-year-olds. The total number of allergic children was by 50 % higher in 2001 compared to 1996, the increase being statistically significant for all age groups, boys and girls. Six cities (one third of all cities monitored) showed significantly increased percentages of allergic children.

The mean annual concentrations of sulphur dioxide did not exceed 20 µg/m3 in any of the cities monitored. Nitrogen oxide pollution is stable in nature, its concentrations slightly increased compared to those of 2000. In some localities, the concentrations are close to the concentration limit effective in 2001, which was exceeded in Děčín, Prague 5 and Prague 8. Higher concentrations of carbon monoxide in ambient air persist in the Prague conurbation with heavy traffic, 31 % of them exceeding the daily concentration limit. Pollution with particulate matter, i.e. fractions TSP and PM10, is stable, the annual concentration limit for the TSP fraction was exceeded in Prague 8 (78.2 µg/m3), the WHO recommended admissible concentration of PM10 was exceeded in 11 cities (Ostrava, Karviná, Ústí nad Labem, Olomouc, Děčín and six Prague districts). Nowhere did the annual arithmetical mean exceed the limits either set or recommended for the metals monitored, the only exception being nickel, for which the suggested annual concentration limit was exceeded in 10 cities. Pollution with the elements monitored between 1995 and 2001 shows either a slightly decreasing trend (lead, arsenic) or remains rather stable (cadmium, chromium) without any important oscillation, the only exception being the concentrations of nickel showing high variability (one order of magnitude) even for the same locality.

Benzo[a]pyrene remains of the highest concern among the polycyclic aromatic hydrocarbons, its maximum admissible concentration recommended was exceeded in all localities monitored (most frequently in Ostrava, for more than 80 % of the results). In Karviná, Prague and Plzeň, over half of the concentrations established exceeded the maximum admissible limit for benzo[a]pyrene. The recommended limit for benzo[a]anthracene was exceeded in all cities except for Brno, most frequently in Ostrava and Karviná (about one quarter of the concentrations established). The carcinogenic potential of the sum of the polycyclic aromatic hydrocarbons monitored (TEQ) is highest in Ostrava (10.1 ng/m3) and Karviná (8.7 ng/m3) and is three times higher in these two cities than that in Prague and Plzeň and five times higher than that in Ústí nad Labem and Hradec Králové. Analysis of long-term time series of the measuring results obtained in five cities (Prague 10, Karviná, Brno, Plzeň and Žďár nad Sázavou) for benzo[a]anthracene, benzo[a]pyrene, sum of PAHs and TEQ showed in all cities complicated non-linear trends difficult to be described unambiguously as either upward or downward ones and a marked seasonality with a summer minimum (decrease by one order of magnitude). Close correlations were also found between the levels of benzo[a]anthracene and those of benzo[a]pyrene.

The recommended maximum admissible concentrations of VOCs, i.e. benzene, toluene, sum of xylenes, styrene and trimethylbenzene, have been exceeded only exceptionally.

The annual index of air quality remains relatively stable, showing an insignificant increase in 22 cities compared to that of 2000. Potential exposure to concentrations exceeding the exposure limits was found in 1.7 % of the population monitored, namely for the sum of nitrogen oxides, the concentrations of which, after a marked deterioration between 1994 and 1995, have been stable. The population is exposed (indiscriminately) to the highest mean concentrations of particulate matter. As much as 87 % of the population monitored are exposed to mean annual PM10 concentrations over 20 µg/m3.

Based on the indoor air monitoring data obtained in 1999–2001, significance of exposure to selected airborne pollutants (formaldehyde, benzene, nitrogen dioxide) from outdoor was compared with that from indoor. The relevance of indoor air exposure depends on time spent indoors: e.g. a preschool child spends 5.5 times more time at home than at nursery school and 2.7 times more time indoors than outdoors, and on pollutant concentrations in indoor and outdoor air. The significance of indoor air as a prevailing source of exposure decreases for the pollutants studied in the following order: formaldehyde, benzene, nitrogen dioxide, exposure to the two latter also varying with localities. For instance, in Brno, exposure to nitrogen dioxide from indoor air is comparable to or higher than that from outdoor air in 80 % of the dwellings and all nursery schools monitored.

Fig. 4.1a Treated acute respiratory diseases excluding influenza, children 1–5 years, 1995–2001
Fig. 4.1b Treated acute respiratory diseases excluding influenza, children 6-14 years, 1995-2001
Fig. 4.2a Structure of allergic diseases in children, 2001
Fig. 4.2b Prevalence of allergic diseases in the selected age groups, 2001
Fig. 4.2c Proportion of diagnoses on the total allergic diseases in the cities, 2001
Fig. 4.2d Frequency of allergic children in different age groups in 1996 and 2001
Fig. 4.2e Frequency of allergy diagnoses in children in 1996 and 2001
Fig. 4.2f Frequency of allergic children in the cities in 1996 and 2001
Fig. 4.3a Sulphur dioxide pollution - annual arithmetic mean, 2001
Fig. 4.3b Concentration range of sulphur dioxide - annual arithmetic mean, 1991–2001
Fig. 4.3c Particulate matter pollution, TSP - annual arithmetic mean, 2001
Fig. 4.3d Concentration range of particulate matter, TSP - annual arithmetic mean, 1991–2001
Fig. 4.3e Particulate matter pollution, fraction PM10 - annual arithmetic mean, 2001
Fig. 4.3f Concentration range of particulate matter, fraction PM10 - annual arithmetic mean, 1991–2001
Fig. 4.3g Sum of nitrogen oxides pollution - annual arithmetic mean, 2001
Fig. 4.3h Concentration range of nitrogen oxides - annual arithmetic mean, 1991–2001
Fig. 4.3i Nitrogen monoxide pollution - annual arithmetic mean, 2001
Fig. 4.3j Concentration range of nitrogen monoxide - annual arithmetic mean, 1995–2001
Fig. 4.3k Nitrogen dioxide pollution - annual arithmetic mean, 2001
Fig. 4.3l Concentration range of nitrogen dioxide - annual arithmetic mean, 1995–2001
Fig. 4.3m Carbon monoxide pollution - annual arithmetic mean, 2001
Fig. 4.3n Concentration range of carbon monoxide - annual arithmetic mean, 1995–2001
Fig. 4.3o Ozone pollution - annual arithmetic mean and 95th percentile of daily concentration, 2001
Fig. 4.3p Concentration range of ozone - annual arithmetic mean, 1995–2001
Fig. 4.4 Air Quality Index (AQI), 1995–2001
Fig. 4.5 Distribution of the population according to the potential exposure to selected pollutants (in intervals of the annual limit rate IHr), 1995–2001
Fig. 4.6a Polycyclic aromatic hydrocarbon pollution, (PAHs) - annual arithmetic mean of PAHs and toxic equivalent TEQ (BaP), 2001
Fig. 4.6b Benzo[a]pyrene toxic equivalent, TEQ (BaP) - annual arithmetic mean, 1997–2001
Fig. 4.6c Mean monthly values of TEQ (BaP), 1997–2001
Fig. 4.6d Benzo[a]anthracene and benzo[a]pyrene pollution - annual arithmetic mean, 2001
Fig. 4.6e Volatile organic compound pollution, (VOCs) - annual arithmetic mean, 2001
Fig. 4.7a Arsenic air pollution - annual arithmetic mean, 2001
Fig. 4.7b Cadmium air pollution - annual arithmetic mean, 2001
Fig. 4.7c Nickel air pollution - annual arithmetic mean, 2001
Fig. 4.7d Arsenic in particulate matter - annual arithmetic mean, 1991–2001
Fig. 4.7e Cadmium in particulate matter - annual arithmetic mean, 1991–2001
Fig. 4.7f Chromium in particulate matter - annual arithmetic mean, 1991–2001
Fig. 4.7g Nickel in particulate matter - annual arithmetic mean, 1991–2001
Fig. 4.7h Lead in particulate matter - annual arithmetic mean, 1991–2000
Fig. 4.7i Manganese in particulate matter - annual arithmetic mean, 2001
Fig. 4.8 GIS layers of nitrogen dioxide concentrations in Brno with monitored dwellings location

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