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Biomedical subjects

J Hrsak

Publications and source records attributed to J Hrsak.

15 recordsLinked to original sources
PubMed2005

Measurements of ozone concentrations in Zagreb.

Ozone concentrations were measured in Zagreb at four sites from May 1999 to April 2001 in order to categorize the air quality with respect to ozone. In the summer of 2000, the ozone measurements were also extended to four sites in the suburbs of Zagreb. Methods of active and passive sampling with nitrite ion as a reagent were used. In the northern part of the town ozone was analyzed by an automatic device. Automatic device measurements in the years 1999 and 2000 showed that hourly averages of ozone concentrations did not exceed the Croatian recommended value of the 98th percentile (180 micro/g m(-3)). Over the two-year period, 24-h averages occasionally exceed 110 microg m(-3) in city center and in the northern part of the town. Regardless of these isolated examples, ozone was well within acceptable concentrations. Ozone concentrations measured in summer 2000 were higher in the suburbs of Zagreb than in the city. The 98th percentile values higher than 110 microg m(-3) were recorded at three sites.

Cities↗
PubMed2000

Levels of nitrogen dioxide in the Zagreb air.

Surveillance of NO2 in Zagreb started in 1994 at five measuring sites. This paper presents the levels and trends of NO2 annual mean values for the period between 1994 and 1998. The obtained data are compared with the recommended and limit values according to the Law on Air Quality Protection in Croatia and the Ordinance on Recommended and Limit Air Quality Values. For the past five years, ever since the measurement commenced, the concentration levels of NO2 in Zagreb have kept between the national recommended and limit values at all measuring sites, indicating that the air has been moderately polluted. This paper also shows the variations of monthly mean values through 1998 at all sites. The levels of NO2 in the northern part of Zagreb were measured at two distances from traffic. Daily variations in the levels were measured near the road and presented as hourly averages for workdays and weekends in winter and in summer reflecting the activity pattern of emission sources.

Air Pollutants↗
PubMed2000

Lead, manganese, and cadmium content in PM10 and PM2.5 particle fractions--a pilot study.

This paper describes a pilot study of lead, manganese, and cadmium content in thoracic particle fraction and high-risk respirable fraction of airborne particles. Samples were collected at one measuring site in Zagreb during autumn 1998 and spring 1999. The results show that the total heavy metal contents is found in the high-risk respirable particle fraction, and point to two main pollution sources, the first for lead and manganese and the other for cadmium.

Air Pollutants↗
PubMed1999

Short-term effects of ambient nitrogen oxides on the number of emergency asthma cases in Zagreb, Croatia.

The paper describes an investigation of short-term effects of NO2 concentrations in the air on the number of emergency room visits caused by respiratory impairments, particularly asthma in adults and children. The data were collected from clinical emergency room records from July 1, 1994 to December 31, 1995. Concurrently, readings of average weekly concentrations of NO2 (microgram/m3), average weekly temperature (degree C), air pressure (kPa), and relative humidity (%) were registered. Trend and seasonality effects were estimated by the locally weighted regression (LOESS). After standardising for trend, seasonality, and meteorological conditions, the number of cases was regressed on weekly NO2 concentration, including the current and the previous week concentrations and autocorrelated residual. The weekly average NO2 concentrations were significantly associated with the number of emergency asthma cases for children and adults and with the total number of emergency respiratory cases in children, but not in adults. The results suggest that health effects of NO2 on risk groups can be detected even in moderately polluted environments. The effect is more pronounced in children.

Adult↗
PubMed1999

Air pollution studies.

The aim of this paper is to give an overview of the research in the area of air pollution, carried out exclusively at the Institute for Medical Research and Occupational Health and performed by the scientists of the Institute. For the past fifty years, air quality has been studied at work, in the ambient air of urban and industrial areas, and in various indoor environments without occupational exposure. Methods for sampling and measuring air pollutants have been introduced or developed and verified. The behaviour and the fate of air pollutants in the environment have also been investigated. Since the primary goal of the studies was to assess the extent of human exposure to air pollutants, the data were used to calculate the risk for various population groups. A dynamic model of exposure for various population groups relied on calculations of collected data, taking into account time spent in various microenvironments. This text describes the cooperation of the Institute with other institutions and agencies on the national and international level and outlines the current and prospective activities.

Air Pollution↗
PubMed1997

Emergency cases of chronic obstructive pulmonary disease (COPD) in adults and air pollution in Zagreb.

The aim of this study was to assess a possible relationship between the concentration of total suspended particles (TSP) and aggravation of symptoms in patients with chronic obstructive pulmonary disease (COPD) with regard to the trend, seasonality and weather conditions. Data on the number of COPD patients reporting aggravated symptoms, mean TSP concentrations, temperature, air pressure, and relative humidity were collected daily for years 1994 and 1995 in Zagreb, Croatia. The authors found a statistically significant correlation between the number of aggravated COPD cases and the TSP concentrations on the previous day. There was a significant autocorrelation in residuals with a lag of 8 days. The estimated value of the regression coefficient for the concentration of TSP on the previous day was 0.001692 (s.e. = 0.000797, p = 0.0345). The estimated relative risk, corresponding to a change of 10 micrograms/m3 in the mean daily concentration of suspended particles, was 1.184 (95% confidence interval: 1.013-1.385).

Adult↗
PubMed1995

Total suspended particulate matter concentrations in Zagreb during the 1975-1993 period.

Daily average mass concentrations of total suspended particulate matter were measured at three sampling sites in Zagreb, and evaluated for the period April 1975-March 1993. Each sampling site represented a different town area (residential, business and administrative, industrial) with different traffic density and type of energent used for space heating. The time trends of concentration levels could, to a certain extent, be attributed to traffic flow modification in the vicinity of the sampling sites, introduction of natural gas in dwellings and degree of energy consumption influenced by the standard of living. Periodograms show a well pronounced seasonal dependence of total suspended particulate matter concentrations, with high concentrations during winters. Analysis of the results in respect to the European Community air quality limits (1) and the levels of other pollutants (SO2 and smoke) leads to the conclusion that particulates being a persistent permanent problem have become a major issue concerning ambient air pollution in Zagreb.

Air Pollutants↗
PubMed1991

Assessment of exposure to lead and cadmium through air and food in inhabitants of Zagreb.

Exposure to lead and cadmium was monitored in a group of 17 non-smoking women in Zagreb. The monitoring included measurement of the intake of the two metals via air and the diet during a period of seven days. Duplicate daily diets and air filter samples were collected for analysis of lead and cadmium. To check the intake of lead and cadmium with the daily diet, faeces were collected and analysed. The mean gastrointestinal absorption was estimated to be 4.9 micrograms/day for lead and 0.75 micrograms/day for cadmium. These values were derived from faecal data which were assumed to be more reliable. The daily absorption through inhalation estimated on the basis of air analysis was 2.7 micrograms for lead and 0.03 micrograms for cadmium.

Adult↗
PubMedDate not supplied

A follow-up study in a lead smelter community following the introduction of an effective pollution control system.

A follow-up study using biological and environmental monitoring was performed in a lead smelter community to assess the health risk of inhabitants and to establish how long it takes after the introduction of an effective emission control system to declare a lead-contaminated area safe for normal living. In specific population groups (mothers and children) biological indicators of lead exposure and lead effect on hemoglobin synthesis were determined 2 years before and 11 consecutive years after the installation of bag filters. At the same time lead was monitored in the airborne and deposited particulates, in household dust and in soil. The results clearly show that the process of normalization is rather slow. The difference in blood lead and erythrocyte delta-aminolevulinic acid dehydratase between the exposed and control groups, even 12 years after bag filters installation, was still remarkable. It appears that soil, contaminated with lead from past exposure, is a major source of increased lead absorption in a population for many years.

Adult↗