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Biomedical subjects

G Hoek

Publications and source records attributed to G Hoek.

At least 55 records · Page 3Linked to original sources
PubMed1994

Respiratory effects of low-level photochemical air pollution in amateur cyclists.

A group of male amateur cyclists was studied in the summer of 1991 in the east of the Netherlands. Lung function was measured before and after training sessions or competitive races on a number of occasions. Continuous heart rate monitors were employed to document exercise levels. Heart rate averaged 161 beats/min during training, and 176 beats/min during races. Exercise duration averaged 75 min. Ozone concentrations during exercise were obtained from the nearest stations of the National Monitoring Network. The difference between pre- and postexercise lung function values was related to these ozone concentrations. Ozone concentrations were low on most occasions with an average of 87 micrograms/m3 and a maximum of 195 micrograms/m3. The difference between pre- and postexercise lung function was found to be negatively related to the ozone concentration during exercise. When all observations obtained at ozone concentrations higher than 120 micrograms/m3 were removed from the analysis, the relationship with ozone was still significant. The data also suggested that effects of ozone on lung function were stronger in midsummer than in the late summer. The difference between pre- and postexercise acute symptoms was positively related to ozone, for shortness of breath, chest tightness, and wheeze. Cough and eye irritation were not related to ozone. These results indicate that in healthy young men vigorously exercising outdoors, ozone is related to lung function changes and acute respiratory symptom changes at low levels of exposure.

Adolescent↗
PubMed1993

Acute effects of ambient ozone on pulmonary function of children in The Netherlands.

In the spring and summer of 1989 an epidemiologic study was conducted to evaluate the acute effects of photochemical air pollution episodes on pulmonary function of children living in three nonindustrial towns in the Netherlands. Spirometry was performed repeatedly in the schools of the children, mostly during the morning hours. Data from 533 children having more than four valid pulmonary function tests were included in the analyses. The association between previous-day ambient ozone concentration and pulmonary function was evaluated, using individual linear regression analysis and subsequent evaluation of the distribution of individual regression coefficients. One hour maximum ambient ozone concentrations frequently exceeded 160 micrograms/m3 but were all lower than the Dutch Air Quality Guideline of 240 micrograms/m3 for all three populations. Significant negative associations of previous-day ambient ozone with FVC, FEV1, peak expiratory flow (PEF), and maximal midexpiratory flow (MMEF) were observed. There were indications of systematic differences in responses among the children. Children with chronic respiratory symptoms did not have a stronger response than children without these symptoms.

Air Pollution↗
PubMed1993

Effect of ambient winter air pollution on respiratory health of children with chronic respiratory symptoms.

The acute respiratory effects of ambient air pollution were studied in a panel of 73 children with chronic respiratory symptoms in the winter of 1990 to 1991. The participating children were selected from all children aged 6 to 12 yr in Wageningen and Bennekom, two small, nonindustrial towns in the east of the Netherlands. Peak flow was measured twice daily with MiniWright meters. A diary was used to register the occurrence of acute respiratory symptoms and medication use by the children. Exposure to air pollution was characterized by the ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), black smoke (BS), and particulate matter less than 10 microns (PM10). Associations between air pollution concentrations and health outcomes were analyzed using time series analysis. During the study period an air pollution episode occurred, with moderately elevated concentrations of PM10 and SO2. There were 6 days with 24-h average PM10 concentrations in excess of the WHO suggested lowest observed effect level of 110 micrograms/m3. After adjustment for ambient temperature, there were small but statistically significant negative associations of PM10, BS, and SO2 with both morning and evening PEF. There was a consistent positive association between PM10, BS, and SO2 with the prevalence of wheeze and bronchodilator use. Overall, the observed associations suggest a mild to moderate response to these moderately elevated levels of air pollution in a group of potentially sensitive children.

Air Pollution↗
PubMed1993

The relationship between low-level air pollution exposure and short-term changes in lung function in Dutch children.

Following air pollution episodes in the winters of 1985 and 1987, a series of studies was initiated to investigate short-term changes in health status in children in relationship to short-term changes in air pollution concentrations. Air pollution exposure was characterized by measurements of SO2, NO2, PM10, nitrate, sulfate, H+, and HONO. Panels of unselected children were studied in four winters (1987-1991). Lung function was measured repeatedly with spirometry in these children. In the winter of 1990/1991, a panel of children with chronic respiratory symptoms was studied as well, with repeated observations of Peak Expiratory Flow made at the home. The three winters of 87/88, 88/89 and 89/90 were very mild; no air pollution episodes with long range transport from the east occurred. In these three winters, lung function was measured on 86 different days. Altogether, over 800 children participated. H+ concentrations (expressed as H2SO4) were generally below 0.6 microgram/m3, with a maximum of only 3 micrograms/m3. Daily mean SO2 concentrations never exceded 100 micrograms/m3 in this period. Nevertheless, lung function in these unselected children was found to decrease with increasing levels of especially particulate matter air pollution. In the winter of 1990/1991, a minor air pollution episode occurred. Maximum SO2 and PM10 concentrations were 105 micrograms/m3 and 174 micrograms/m3 respectively. This episode was associated with decreased lung function in a group of about 112 unselected children. There was also a relationship with decreased daily PEF readings in a panel of 73 children with chronic respiratory symptoms.

Air Pollutants↗
PubMed1992

Pets, allergy and respiratory symptoms in children.

The relationship between pet ownership and respiratory allergy and symptoms was investigated in a population of 3344 Dutch children of 6-12 years old. Pet ownership was defined by the presence of cats, dogs, birds and/or rodents in the home. The reported prevalence of respiratory allergy and symptoms was lower among children of current pet owners than among children of parents who owned no pets. When past pet ownership was taken into account, however, a different picture emerged. The lowest prevalence of respiratory allergy and symptoms was found in children of current pet owners who had no pets in the past. The next lowest prevalence was found in children of current pet owners who had had pets in the past also. The next highest prevalence was found in children who never had pets in their life. The highest prevalence of reported pet allergy, chronic cough, wheeze, attacks of shortness of breath with wheezing, and doctor-diagnosed asthma was found in children who had pets in the past but not anymore. Past cat ownership especially was associated with a high prevalence of pet allergy and doctor-diagnosed asthma. Almost 2% of the population reported to never have owned pets for health reasons, and more than 12% reported removing pets from the home for health reasons in the past. These results show that selective avoidance and removal of pets leads to distortions of cross-sectional associations between pet ownership and respiratory allergy and disease among children.

Animals↗
PubMed1992

Reproducibility of childhood respiratory symptom questions.

The reproducibility of answers to childhood respiratory symptom questions was investigated by administering two childhood respiratory symptom questionnaires twice, with a one month interval, to the same population of Dutch school children. The questionnaires were completed by the parents of 410 children from 6-12 yrs old. One questionnaire was developed by the World Health Organization (WHO). The other questionnaire was developed for use by school health services and was based mainly on the American Thoracic Society (ATS) questionnaire for respiratory symptoms in childhood. It was called the Child Health Care (CHC) Questionnaire. Half of the parents received a questionnaire in which the WHO questions came first on both occasions, the other half a questionnaire in which the CHC questionnaire came first on both occasions. The reproducibility of the answers was assessed by calculating Cohen's Kappa, a chance-corrected measure of association. Questions about "wheeze", "asthma", "bronchitis", "cough and phlegm", and "pneumonia" were found to give good to excellent reproducibility, with Kappa values ranging from 0.60-0.96. Questions about "phlegm", "cough", "chest congestion" and "runny/congested nose" were less satisfactory in this respect, with Kappa values generally well below 0.60. The reproducibility of the answers did not depend on the order in which the questionnaires were administered, on the gender or age of the child, or on the smoking habits or educational level of the parents.

Child↗
PubMed1992

Time trends in repeated spirometry in children.

In a study on acute health effects of air pollution in the Netherlands, pulmonary function has been measured repeatedly in children aged 7-11 yrs. In study periods of approximately 3 months, 6-10 tests have been made in a group of 1,621 children. The spirometric data have been examined for the presence of trends of pulmonary function with day of study, independent of air pollution. Peak expiratory flow (PEF) increased more than expected from normal lung growth, whereas for maximal mid-expiratory flow (MMEF) a decrease with time was observed. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) a smaller than expected increase with time was observed. The observed deviation from the expected pattern was larger for the children with a one week interval between successive tests than for the children with a three week interval. For FVC and FEV1 a non-linear relationship with time was observed, for PEF and MMEF this relationship was approximately linear. The particular changes of spirometric variables with time need to be taken into account when repeated lung function tests are performed to investigate acute effects of air pollution exposure.

Air Pollution↗
PubMed1991

[The comparative characteristics of different forms of allergens from mites of the genus Dermatophagoides].

The comparative study of allergenic preparations of Dermatophagoides mites [correction of ticks] from different manufacturers and the international standard preparations of such allergens was made. D. pteronyssinus and D. farinae allergens from the USSR and the Netherlands were studied. The samples under study were evaluated in a complex of in vivo and in vitro experiments. The preparations produced in the USSR and in the Netherlands exhibited pronounced specificity, but the allergens of both species from the Netherlands were more active. Some differences in the immunochemical characteristics of the preparations were noted.

Adolescent↗
PubMed1990

[The effect of elevated ozone levels in the ambient air on lung function of children engaged in sports].

In the summer of 1989, ozone levels in the ambient air were regularly found to be increased in The Netherlands. The question was studied whether this affected pulmonary function of children aged 7 to 12 years practising sports in the open air. Before and after sessions of training in the open air, the peak expiratory flow rate was determined using peak flow meters (mini-Wright). This was done on 37 different days with varying ozone concentrations. Measurements were carried out on four or more days in a total of 65 children. No correlation between ozone concentration during training and differences between pre- and post-training peak flows was found. No correlation was found either between the maximal ozone concentration on a given day and the peak flow at the end of training on that day. However, a negative correlation was found between the maximal ozone concentration on the day preceding the pulmonary function tests and the peak flow after the training.

Air Pollutants↗
PubMed1990

Effects of air pollution episodes on pulmonary function and respiratory symptoms.

In January 1985, a decline of primary school children's pulmonary function was observed during an air pollution episode. Ambient 24 hour average levels of SO2, TSP and RSP were in the range of 200-250 micrograms/m3. The response persisted for at least two weeks. In January 1987, again a decline of school children's pulmonary function was observed associated with an air pollution episode. Levels of TSP were about as elevated as in the 1985 episode. Two weeks after the episode, lung function levels were even lower than during the episode. In June 1987 a long term study was started to investigate potential effects of winter and summer air pollution episodes on pulmonary function and occurrence of acute respiratory symptoms of primary school children. An important issue for this study is the characterization of short term variation of lung function in absence of air pollution. Exposure is characterized by ambient levels of several gases (SO2, NO2, O3, HNO3), PM10, TSP and components of particulate matter (SO4(2-), NO3-, H-, NH4+). Sampling is being conducted on a daily basis to obtain a continuous exposure estimate. In the winter of 1987/1988, no air pollution episodes were observed. The study will continue through the winters of 1988/1989, and 1989/1990.

Air Pollution↗
PubMed1989

Pulmonary function changes associated with an air pollution episode in January 1987.

In January 1987, an air pollution episode occurred in central and western Europe. Levels of SO2, NO2, black smoke, sulphates and other components were elevated, with 24 hour average concentrations of SO2 reaching a maximum of close to 300 micrograms/m3 in an area in the southeast of the Netherlands. Pulmonary function was measured in a group of children of 6-12 years old at the end of the episode, and also two and three and a half weeks after the episode. A baseline lung function value was obtained about three months before the episode. Pulmonary function growth between baseline and retest dates was estimated from a simple growth model which was validated using measured pulmonary function growth data from a longitudinal study. A decline of pulmonary function (FVC, FEV1 and PEF) from predicted baseline levels was observed, starting on the last day of the episode. Two weeks after the episode, FVC, FEV1, PEF and MMEF were all decreased, and three and a half weeks after the episode, there was still a deficit compared to predicted baseline levels for FVC and FEV1.

Air Pollution↗
PubMed1984

The relationship between indoor nitrogen dioxide concentration levels and personal exposure: a pilot study.

A small, personal monitoring study was performed in a subpopulation (14 families) of a case-control study on the relationship between indoor nitrogen-dioxide exposure and respiratory diseases of schoolchildren. Mothers, schoolchildren and pre-schoolchildren were asked to carry duplicate Palmes diffusion tubes during one week. Simultaneously nitrogen-dioxide concentrations were measured in the kitchen, living room, bedroom, outdoors and--for a few participants--at school and at work. Information on time activity patterns was gathered by means of a self administered diary. Several models for estimating exposure were constructed and tested against measured exposure. The personal exposure of the participants could well be explained by models containing indoor concentrations. Models with time-weighted average concentrations did not explain personal exposure better than models containing indoor concentrations. A calculated time-weighted average exposure was found to underestimate measured personal exposure by an average 20%, probably because the average concentration in a location does not necessarily reflect the actual exposure in that location. Personal exposure of mothers and children was very similar and highly correlated, indicating that the personal exposure of the mother might be a reasonable estimate for the exposure of the child.

Adult↗
PubMed1984

Indoor nitrogen dioxide pollution and respiratory symptoms of schoolchildren.

The influence of indoor nitrogen-dioxide exposure on respiratory symptoms of schoolchildren was investigated in a case-control study. The election method used was useful in obtaining symptomatic children, but insufficient in defining cases and controls without additional information. No relationship between indoor NO2 and respiratory symptoms was found. Bias may have been present, especially because of the high mobility of the study population. Attempts to estimate historical exposure were inaccurate. Therefore the results do not exclude that an association between indoor NO2 and respiratory symptoms exists.

Air Pollutants↗
PubMedDate not supplied

Estimation of long-term average exposure to outdoor air pollution for a cohort study on mortality.

Recent prospective cohort studies have suggested that long-term exposure to low levels of particulate matter (PM) air pollution is associated with increased mortality due to, especially, cardio-pulmonary disease. Exposure to ambient air pollution was estimated mostly as city average concentrations, assuming homogenous exposure within the city. We used an ongoing cohort study - The Netherlands Cohort Study (NLCS) on diet and cancer - to investigate the relationship between traffic-related air pollution and mortality. The baseline data collection took place in 1986. A study was conducted to develop methods for exposure assessment and evaluate the contrast in exposure to air pollution within the cohort. Assessment of long-term exposure to two traffic-related air pollutants, Black Smoke (BS) and Nitrogen Dioxide (NO(2)), consisted of separate estimation of regional background, urban background, and local traffic contributions at the home address. Interpolation of concentration data from a routine monitoring network was used to estimate the regional background concentration. A regression model relating degree of urbanization to air pollution was used to allow for differences between different towns/neighborhoods of cities. Distance to major roads was calculated to characterize local traffic contributions, using a Geographic Information System (GIS). Interpolation resulted in reasonably precise regional background estimation when distant sites were not used and distance squared was used as the weight. Cross-validation showed that prediction errors were about 15% of the range in regional background concentration. Urban and local scales contributed significantly to the contrast within the cohort. Prediction errors for estimating the urban background were about 25% of the range in background concentrations. When the developed model was applied to the study cohort, there was substantial contrast in estimated exposure to BS and NO(2). About 90% of the study population lived 10 years or more at its 1986 home address - supporting the use of the estimated concentration at the 1986 address as a relevant exposure variable.

Aged↗
PubMedDate not supplied

Acute effects of a winter air pollution episode on pulmonary function and respiratory symptoms of children.

The acute respiratory effects of a wintertime air pollution episode were studied in a general population sample of 112 children who were 7-12 y of age and who lived in a nonurban community. Spirometry was performed on 6 d, with a fixed interval of 3 wk between successive tests. During an air pollution episode, an additional pulmonary function test was made. Acute respiratory symptoms of the children were noted in a diary. Ambient concentrations of sulfur dioxide, black smoke, particulate matter with an aerodynamic diameter less than 10 microns, and nitrogen dioxide were considered as exposure variables. The association of air pollution with pulmonary function and prevalence of acute respiratory symptoms was assessed by individual linear regression analysis and time series analysis, respectively. In February 1991, an air pollution episode occurred during which daily average sulfur dioxide concentrations were slightly above 100 micrograms/m3, and particulate matter (with an aerodynamic diameter of less than 10 microns) concentrations reached 174 micrograms/m3. During the episode, forced vital capacity, forced expiratory volume in 1 s, and maximal mid-expiratory flow were lower than on baseline tests. Significant negative associations were found between the concentration of sulfur dioxide, black smoke, and particulate matter with an aerodynamic diameter of less than 10 microns. No association between prevalence of acute respiratory symptoms and the concentration of these compounds was found.

Acute Disease↗
PubMedDate not supplied

Effect of ambient ozone on peak expiratory flow of exercising children in The Netherlands.

The potential effects of elevated ozone concentrations in The Netherlands were evaluated by the measurement of peak expiratory flow (PEF) of exercising children. Peak expiratory flow was measured with mini-Wright peak flow meters, both before and after out-door sports training. The relationship between PEF and ozone was investigated with individual regression analysis. The difference of PEF after and before training (delta PEF) and the PEF after training were used as dependent variables. The ozone concentration during the training and the 1-h maximum ozone concentration of the same and the previous day were used as independent variables. The highest observed 1-h maximum ozone concentration was 236 micrograms/m3. delta PEF was unrelated to the ambient ozone concentration during training. Peak flow measured after the training was positively correlated with ambient temperature. The high correlation between ozone and temperature prevented the evaluation of effects of the maximum ozone concentration of the same day on PEF after training. A small negative association of borderline statistical significance between PEF after training and previous-day maximum ozone was observed.

Air Pollutants↗