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The Pollution Effects on Asthmatic Children in Europe (PEACE) study is a multicentre study of the acute effects of particles with a 50% cut-off aerodynamic diameter of 10 μm (PM10), black smoke (BS), sulphur dioxide (SO2) and nitrogen dioxide (NO2) on the respiratory health of children with chronic respiratory symptoms. The study was conducted in the winter of 1993/1994 by 14 research centres in Europe. A total of 2,010 children, divided over 28 panels in urban and suburban locations, was followed for at least 2 months. Exposure to air pollution was monitored on a daily basis. Health status was monitored by daily peak expiratory flow (PEF) measurements and a symptom diary. The association between respiratory health and air pollution levels was calculated with time series analysis. Combined effect estimates of air pollution on PEF or the daily prevalence of respiratory symptoms and bronchodilator use were calculated from the panel-specific effect estimates. Fixed effect models were used and, in cases of heterogeneity, random effect models. No clear associations between PM10, BS, SO2 or NO2 and morning PEF, evening PEF, prevalence of respiratory symptoms or bronchodilator use could be detected. Only previous day PM10 was negatively associated with evening PEF, but only in locations where BS was high compared to PM10 concentrations. There were no consistent differences in effect estimates between subgroups based on urban versus suburban, geographical location or mean levels of PM10, BS, SO2 and NO2. The lack of association could not be attributed to a lack of statistical power, low levels of exposure or incorrect trend specifications. In conclusion, the PEACE project did not show effects of particles with a 50% cutoff aerodynamic diameter of 10 μm, black smoke, sulphur dioxide or nitrogen dioxide on morning or evening peak expiratory flow or the daily prevalence of respiratory symptoms and bronchodilator use.

A multicentre study (Pollution Effects on Asthmatic Children in Europe (PEACE)) project investigated the relationship between the air pollution and daily variation of respiratory health in children with chronic respiratory symptoms. Data were collected on 66 children in Prague and 68 children in Benesov, Czech Republic. The panels were followed from January 17 to April 12, 1994. Respiratory symptoms and peak expiratory flow were recorded on a daily basis in a diary. Ambient air pollutants as well as meteorological parameters were measured at local monitoring stations on a daily basis. Mean particles with a 50% cut-off aerodynamic diameter of 10 μm (PM10) (SO2) levels were 53 (114) μg.m-3 and 50 (31) μg.m-3 in Prague and Benesov, respectively. The association between air pollution and health outcomes was analysed using time series regression models. Between air pollution and symptom prevalence a small association was found, also between air pollution and prevalence of medication use. No association of air pollution and peak flow or between air pollution and respiratory symptom incidence indicating an adverse effect could be detected. In conclusion, a small effect of air pollution on the prevalence of respiratory symptoms and medication use was detected.

This report presents a halfway score of the research project "Winter smog and Traffic", one of the themes of the research programme "Air Pollution and Health". A state of the art is presented of the health effects associated with exposure to winter smog and of the toxicological effects caused by the inhalation of particles. A summary of the assessment of air quality and the results of epidemiological research is presented. Some policy questions are answered as far as possible at this stage of the project. Finally, an outline of a plan of activities is presented which is based on the policy needs and the most serious gaps in knowledge.

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.

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.

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.