Short term fluctuations in air pollution and hospital admissions of the elderly for respiratory disease.

BACKGROUND--Several recent studies have reported associations between short term changes in air pollution and respiratory hospital admissions. This relationship was examined in two cities with substantially different levels of sulphur dioxide (SO2) but similar levels of airborne particles in an attempt to separate the effects of the two pollutants. Significant differences in weather between the two cities allowed the evaluation of that potential confounder also. METHODS--Daily counts of admissions to all hospitals for respiratory disease (ICD 9 460-519) were constructed for persons aged 65 years and older in two cities - New Haven, Connecticut and Tacoma, Washington. Each city was analysed separately. Average daily concentrations of SO2, inhalable particles (PM10), and ozone were computed from all monitors in each city, and daily average temperature and humidity were obtained from the US weather service. Daily respiratory admission counts were regressed on temperature, humidity, day of the week indicators, and air pollution. A 19 day weighted moving regression filter was used to remove all seasonal and subseasonal patterns from the data. Possible U-shaped dependence of admissions on temperature was dealt with using indicator variables for eight categories each of temperature and humidity. Each pollutant was first examined individually and then multiple pollutant models were fitted. RESULTS--All three pollutants were associated with respiratory hospital admissions of the elderly. The PM10 associations were little changed by control for either ozone or SO2. The ozone association was likewise independent of the other pollutants. The SO2 association was substantially attenuated by control for ozone in both cities, and by control for PM10 in Tacoma. The magnitude of the effect was small (relative risk 1.06 in New Haven and 1.10 in Tacoma for a 50 micrograms/m3 increase in PM10, for example) but, given the ubiquitous exposure, this has some public health significance. CONCLUSIONS--Air pollution concentrations within current guidelines were associated with increased respiratory hospital admissions of the elderly. The strongest evidence for an independent association was for PM10, followed by ozone. These results are consistent with other studies and suggest that lowering air pollution concentrations would have some impact on public health.     

Temporal association between hospital admissions for asthma in Birmingham and ambient levels of sulphur dioxide and smoke.

BACKGROUND--A study was performed to determine whether daily and weekly variations in the levels of smoke and sulphur dioxide (SO2) in Birmingham are related to hospital admissions for asthma and acute respiratory diseases. METHODS--Daily numbers of hospital admissions for asthma (ICD code 493) and acute respiratory conditions (ICD 466, 480-486, 490-496) for residents of Birmingham between 1988 and 1990 were obtained from West Midlands RHA Körner inpatient data. Average daily levels of sulphur dioxide and smoke were obtained from Birmingham City Council for the same period, together with daily meteorological summaries from the Department of Geography, University of Birmingham. With the exception of one day, all air pollution measurements remained within current EC guide levels. Data were divided into seasons and the relation between hospital admissions and pollutant levels were explored by stepwise least squares regression models. Meteorological variables (temperature, pressure, humidity) were entered into the model if they showed significant association with hospital admissions during the season in question. Analysis was undertaken for daily (same day and lagged by two days) and weekly pollutant levels. Admissions were lagged behind pollution levels to allow for delayed effects of pollutants. RESULTS--The mean daily level of smoke was 12.7 micrograms/m3 and of SO2 was 39.1 micrograms/m3, with maxima of 188.3 micrograms/m3 and 126.3 micrograms/m3, respectively. Significant associations were found between hospital admissions for respiratory disease lagged by two days, and smoke and SO2 levels during winter. Associations between admissions for asthma and smoke and SO2 levels were significant at the 5% level. These were independent of temperature, pressure, and humidity. Stepwise regression including both pollutants showed that smoke, but not SO2, was a significant independent predictor of hospital admissions for both asthma and all respiratory conditions. During winter a rise of 100 micrograms/m3 smoke might result in five (95% CI 0.6 to 9) more asthma admissions and 21.5 (95% CI 10 to 33) more acute respiratory admissions each day in Birmingham. A 100 micrograms/m3 rise in SO2 might result in four (0 to 7) more asthma admissions and 15.5 (6 to 25) more respiratory admissions each day. Independent associations were also found between weekly mean smoke and SO2 levels and all respiratory admissions during autumn and winter. During summer, daily mean smoke and SO2 levels were significantly associated with non-lagged daily admissions for all respiratory diseases (p < 0.02). There was no association between air pollution and hospital admissions during spring. CONCLUSIONS--Daily variations in smoke and SO2 levels are significantly associated with hospital admissions for asthma and respiratory disease during winter in Birmingham at levels of air pollutants within the EC guide levels. This association was independent of potential confounding effects of weather (temperature, pressure, humidity) and suggests that current levels of air pollution can still produce significant health effects.     

Urban air pollution and emergency admissions for asthma in four European cities: the APHEA Project

BACKGROUND: A study was undertaken to assess the combined association between urban air pollution and emergency admissions for asthma during the years 1986-92 in Barcelona, Helsinki, Paris and London. METHODS: Daily counts were made of asthma admissions and visits to the emergency room in adults (age range 15-64 years) and children (< 15 years). Covariates were short term fluctuations in temperature and humidity, viral epidemics, day of the week effects, and seasonal and secular trends. Estimates from all the cities were obtained for the entire period and separately by warm or cold seasons using Poisson time-series regression models. Combined associations were estimated using meta- analysis techniques. RESULTS: Daily admissions for asthma in adults increased significantly with increasing ambient levels of nitrogen dioxide (NO2) (relative risk (RR) per 50 micrograms/m3 increase 1.029, 95% CI 1.003 to 1.055) and non-significantly with particles measured as black smoke (RR 1.021, 95% CI 0.985 to 1.059). The association between asthma admissions and ozone (O3) was heterogeneous among cities. In children, daily admissions increased significantly with sulphur dioxide (SO2) (RR 1.075, 95% CI 1.026 to 1.126) and non-significantly with black smoke (RR 1.030, 95% CI 0.979 to 1.084) and NO2, though the latter only in cold seasons (RR 1.080, 95% CI 1.025 to 1.140). No association was observed for O3. The associations between asthma admissions and NO2 in adults and SO2 in children were independent of black smoke. CONCLUSIONS: The evidence of an association between air pollution at current urban levels and emergency room visits for asthma has been extended to Europe. In addition to particles, NO2 and SO2--by themselves or as a constituent of a pollution mixture--may be important in asthma exacerbations in European cities.


     

Association of air pollution with daily GP consultations for asthma and other lower respiratory conditions in London

BACKGROUND: Very few published studies have looked at the effects of air pollution on health in the primary care setting. As part of a large study to examine the association between air pollution and a number of health outcomes, the relationship between daily GP consultations for asthma and other lower respiratory diseases (LRD) and air pollution in London was investigated. METHODS: Time-series analysis of daily numbers of GP consultations controlling for time trends, seasonal factors, day of week cycles, influenza, weather, pollen levels, and serial correlation was performed. Consultation data were available from between 268 718 and 295 740 registered patients from 45-47 London practices contributing to the General Practice Research Database during 1992-4. RESULTS: Positive associations, weakly significant and consistent across lags, were observed between asthma consultations and nitrogen dioxide (NO2) and carbon monoxide (CO) in children and particulate matter of less than 10 microm in diameter (PM10) in adults, and between other LRD consultations and sulphur dioxide (SO2) in children. A consistently negative association with ozone in children was observed in both disease categories. The effect estimates of most pollutants were much larger when analysed separately by season, particularly in the children: percentage change in asthma consultations during the warm season (April-September) for a 10-90th percentile increase in 24 hour NO2 lagged by one day = 13.2% (95% CI 5.6 to 21.3), with CO = 11.4% (95% CI 3.3 to 20.0), and with SO2 = 9.0% (95% CI 2.2 to 16.2). In adults the only association consistent over different lag periods was with PM10 = 9.2% (3.7 to 15.1). The associations of pollution and consultations for LRD were increased mainly in the winter months: percentage change in consultations by children in winter with NO2 = 7.2% (95% CI 2.8 to 11.6), CO = 6.2% (95% CI 2.3 to 10.2), and SO2 = 5.8% (95% CI 1.6 to 10.2). CONCLUSIONS: There are associations between air pollution and daily consultations for asthma and other lower respiratory disease in London. The most significant associations were observed in children and the most important pollutants were NO2, CO, and SO2. In adults the only consistent association was with PM10.     

Temporal relationship between air pollutants and hospital admissions for chronic obstructive pulmonary disease in Hong Kong

AIMS: To assess any relationship between the levels of ambient air pollutants and hospital admissions for chronic obstructive pulmonary disease (COPD) in Hong Kong. METHODS: A retrospective ecological study was undertaken. Data of daily emergency hospital admissions to 15 major hospitals in Hong Kong for COPD and indices of air pollutants (sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm (PM(10)) and 2.5 microm (PM(2.5))) and meteorological variables from January 2000 to December 2004 were obtained from several government departments. Analysis was performed using generalised additive models with Poisson distribution, adjusted for the effects of time trend, season, other cyclical factors, temperature and humidity. Autocorrelation and overdispersion were corrected. RESULTS: Significant associations were found between hospital admissions for COPD with all five air pollutants. Relative risks for admission for every 10 microg/m(3) increase in SO(2), NO(2), O(3), PM(10) and PM(2.5) were 1.007, 1.026, 1.034, 1.024 and 1.031, respectively, at a lag day ranging from lag 0 to cumulative lag 0-5. In a multipollutant model, O(3), SO(2) and PM(2.5) were significantly associated with increased admissions for COPD. SO(2), NO(2) and O(3) had a greater effect on COPD admissions in the cold season (December to March) than during the warm season. CONCLUSION: Ambient concentrations of air pollutants have an adverse effect on hospital admissions for COPD in Hong Kong, especially during the winter season. This might be due to indoor exposure to outdoor pollution through open windows as central heating is not required in the mild winter. Measures to improve air quality are urgently needed.     

Air pollution, pollens, and daily admissions for asthma in London 1987-92

BACKGROUND: A study was undertaken to investigate the relationship between daily hospital admissions for asthma and air pollution in London in 1987-92 and the possible confounding and modifying effects of airborne pollen. METHODS: For all ages together and the age groups 0-14, 15-64 and 65+ years, Poisson regression was used to estimate the relative risk of daily asthma admissions associated with changes in ozone, sulphur dioxide, nitrogen dioxide and particles (black smoke), controlling for time trends, seasonal factors, calendar effects, influenza epidemics, temperature, humidity, and autocorrelation. Independent effects of individual pollutants and interactions with aeroallergens were explored using two pollutant models and models including pollen counts (grass, oak and birch). RESULTS: In all-year analyses ozone was significantly associated with admissions in the 15-64 age group (10 ppb eight hour ozone, 3.93% increase), nitrogen dioxide in the 0-14 and 65+ age groups (10 ppb 24 hour nitrogen dioxide, 1.25% and 2.96%, respectively), sulphur dioxide in the 0-14 age group (10 micrograms/m3 24 hour sulphur dioxide, 1.64%), and black smoke in the 65% age group (10 micrograms/m3 black smoke, 5.60%). Significant seasonal differences were observed for ozone in the 0-14 and 15-64 age groups, and in the 0-14 age group there were negative associations with ozone in the cool season. In general, cumulative lags of up to three days tended to show stronger and more significant effects than single day lags. In two-pollutant models these associations were most robust for ozone and least for nitrogen dioxide. There was no evidence that the associations with air pollutants were due to confounding by any of the pollens, and little evidence of an interaction between pollens and pollution except for synergism of sulphur dioxide and grass pollen in children (p < 0.01). CONCLUSIONS: Ozone, sulphur dioxide, nitrogen dioxide, and particles were all found to have significant associations with daily hospital admissions for asthma, but there was a lack of consistency across the age groups in the specific pollutant. These associations were not explained by confounding by airborne pollens nor was there convincing evidence that the effects of air pollutants and airborne pollens interact in causing hospital admissions for asthma.     

Emergency hospital admissions for respiratory disorders attributable to summer time ozone episodes in Great Britain

BACKGROUND: There is accumulating evidence from various countries, including the UK, that ground level ozone concentrations are associated with increased daily hospital admissions for respiratory diseases. This paper estimates the impact of ozone episodes on daily hospital admissions for respiratory disease in Great Britain by combining locally based exposure-response relationships with mapped estimates of ozone exposure for the population in the summers of 1993 and 1995. METHODS: For the given years the available ozone measurements were used to construct maps of ozone concentrations for each day. The population exposed to a given concentration of ozone on a particular day was calculated from census data using a geographical information system. The additional hospital admissions for respiratory disease were then estimated using a regression coefficient for London. RESULTS: It is estimated that 0.10% (a total of 184) and 0.35% (a total of 643) of hospital admissions for respiratory disorders during the summers of 1993 and 1995, respectively, can be attributed to levels of ozone above 50 ppb (the recommended air quality standard for the UK). A sensitivity analysis for 1995 found that, if no threshold is assumed, the estimate is increased by about twenty fold (6% of admissions attributable). CONCLUSIONS: The additional hospital admissions for respiratory disease attributable to ozone are very small in both absolute and relative terms if a threshold of 50 ppb is assumed, but this estimate is very sensitive to threshold assumptions.


     

Proximity to coke works and hospital admissions for respiratory and cardiovascular disease in England and Wales

BACKGROUND: The incidence of hospital admissions for respiratory and cardiovascular diseases in areas close to operating coke works in England and Wales was investigated. METHODS: A small area study using distance from source as a proxy for exposure was undertaken in subjects aged 65 or over and children under 5 years within 7.5 km of four coke works (1991 estimated populations 87 760 and 43 932, respectively). The main outcome measures were emergency hospital admissions in 1992/3-1994/5 with a primary diagnosis of coronary heart disease (ICD 410-414), stroke (ICD 431-438), all respiratory diseases (ICD 460-519), chronic obstructive pulmonary disease (ICD 491-492), and asthma (ICD 493) in those aged 65 or over, and all respiratory and asthma admissions in children under 5 years of age. RESULTS: At age 65 or over the combined estimate of relative risk with proximity to coke works (per km) ranged from 0.99 (95% CI 0.90 to 1.09) for chronic obstructive pulmonary disease to 1.03 (95% CI 0.94 to 1.13) for asthma. For children under 5 years the combined estimate of risk was 1.08 (95% CI 0.98 to 1.20) for all respiratory disease and 1.07 (95% CI 0.98 to 1.18) for asthma. There was evidence of significant heterogeneity in risk estimates between coke work groups, especially in children under 5 years (p<0.001 and p=0.004 for respiratory disease and asthma, respectively). For the Teesside coke works in North East England the relative risk with proximity (per km) was 1.09 (95% CI 1.06 to 1.12) for respiratory disease and 1.09 (95% CI 1.04 to 1.15) for asthma. CONCLUSIONS: No evidence overall was found for an association between hospital admissions and living near operational coke works in England and Wales. Trends of a higher risk of hospital admission for respiratory disease and asthma among children with proximity to the Teesside plant require further investigation.     

Respiratory effects of air pollution in chronic obstructive pulmonary disease: a three month prospective study

BACKGROUND: A study was undertaken to investigate the relationship between air pollution levels and respiratory symptoms and peak expiratory flow rate (PEFR) in subjects with chronic obstructive pulmonary disease (COPD) living in Christchurch, New Zealand. METHODS: Forty subjects aged over 55 years with COPD completed twice daily diaries for three months during the winter of 1994. Subjects recorded respiratory symptoms, PEFR, outdoor activity, visits to doctor or hospital, and medication use. All were resident within a 5 km radius of the regional council's air pollution monitoring site. Daily and hourly mean pollutant levels (particulates (PM10, nitrogen dioxide (NO2), sulphur dioxide (SO2) and carbon monoxide (CO)) were measured at the monitoring site. RESULTS: Pollution levels were generally low relative to those recorded in previous years. The New Zealand Ministry for the Environment guidelines for PM10 were exceeded on five occasions, and for CO six times. No association was found between PEFR and any of the pollution variables. A rise in the PM10 concentration equivalent to the interquartile range was associated with an increase in night time chest symptoms (relative risk 1.38, 95% CI 1.07 to 1.78). A rise in NO2 concentrations equivalent to the interquartile range was associated with increased reliever inhaler use (relative risk 1.42, 95% CI 1.13 to 1.79) and for 24 hour lag analysis with increased nebuliser use (relative risk 2.81, 95% CI 1.81 to 4.39). There was no increase in the relative risk of other symptoms in relation to pollution levels. CONCLUSIONS: These effects, demonstrated in a small susceptible group of subjects with COPD, indicate that adverse outcomes can be measured in response to pollution levels that are within current guidelines.


     

Personal exposure to nitrogen dioxide and risk of airflow obstruction in asthmatic children with upper respiratory infection

BACKGROUND: Several studies have linked air pollution by nitrogen dioxide (NO(2)) with increased hospital admissions for asthma in children. Exacerbations of asthma in children are often precipitated by upper respiratory infections. It is therefore possible that NO(2) increases the risk of airways obstruction when asthmatic children develop upper respiratory infections. METHODS: To test this hypothesis a sample of 114 asthmatic children aged 7-12 years were followed for a total of up to 13 months. Probable upper respiratory infections were identified by consensus review of daily symptom diaries, and episodes of airways obstruction from serial records of peak expiratory flow (PEF). Personal exposures to NO(2) were measured with Palmes tubes that were changed weekly. Generalised estimating equations were used to assess the relative risk (RR) of an asthmatic exacerbation starting within seven days of an upper respiratory infection according to estimated NO(2) exposure during the one week period from two days before to four days after the onset of the infection. RESULTS: The children were followed for an average of 34 weeks during which 318 upper respiratory infections and 224 episodes of reduced PEF were diagnosed. PEF episodes were much more likely to occur in the seven days following the onset of an upper respiratory infection than at other times. Estimated exposures to NO(2) at the time of infections were generally low (geometric mean 10.6 microg/m(3)). Compared with exposures of < or = 8 microg/m(3), exposures of >28 microg/m(3) were associated with a RR of 1.9 (95% confidence interval 1.1 to 3.4) for the development of an asthmatic episode within seven days of an infection. CONCLUSIONS: The findings give some support to the hypothesis that NO(2) increases the risk of asthmatic exacerbations following respiratory infections, even at relatively low levels of exposure. Further studies in populations with higher exposures would be useful.     

Effects of air pollution on symptoms and peak expiratory flow measurements in subjects with obstructive airways disease.

BACKGROUND--Evidence from laboratory studies suggests that air pollution can produce bronchoconstriction and respiratory symptoms in selected subjects, but the relevance of these findings to exposure to natural pollution is unclear. This study was performed to determine whether air pollution at typical levels found in the UK has demonstrable effects on respiratory function and symptoms in subjects with airways disease. METHODS--Seventy five adult patients with diagnoses of asthma or chronic obstructive pulmonary disease (COPD) were studied for a period of four weeks during which they kept records of their peak expiratory flow (PEF) rates, symptoms (wheeze, dyspnoea, cough, throat and eye irritation), and bronchodilator use. Thirty six patients in whom the provocative dose of methacholine causing a 20% fall in FEV1 was below 12.25 mumol were classified as reactors. Ambient air pollution was measured with absorption spectroscopy. RESULTS--There were modest but significant increases in PEF variability, bronchodilator use, and wheeze with increasing sulphur dioxide levels; bronchodilator use, dyspnoea, eye irritation, and minimum PEF readings were related to ozone levels. In the subgroup of reactors falls in mean and minimum peak flow and increases in wheeze, dyspnoea, and bronchodilator use were associated with increases in levels of both sulphur dioxide and ozone. Some associations were seen with pollution levels on the same day, but for others the pollution effects appeared to be delayed by 24 or 48 hours. Pollution levels did not breach the WHO guide levels during the course of the study. CONCLUSIONS--Increases in environmental levels of ozone and sulphur dioxide are associated with adverse changes in peak flow measurements and both ocular and respiratory symptoms in subjects with obstructive airways disease. Although the peak flow and symptom changes were modest, they occurred at pollution levels below current WHO guide levels.     

A year's trauma admissions and the effect of the weather

PURPOSE OF THE STUDY: To study the admissions to a busy trauma unit on a day-by-day basis over a 1 year period, and to look for any correlation with local weather variation or temporal factors (day of the week, weekends/school holidays, etc.). METHOD: Admissions data for the Trauma Unit at the Leicester Royal Infirmary was collected from an administrative database and ward records for the calendar year of 1998. Admissions were split into four groups: all admissions, adult admissions, admissions for proximal femoral fractures (neck of femur (NOF)) and paediatric admissions. Weather information for the local area was obtained from the Meteorological Office. Details of school holidays were obtained from the local Education Department. The above variables were examined using Poisson regression analysis for their potential importance in explaining day-to-day variation in admission rates for the four groups. RESULTS: For adult and NOF admissions, none of the weather factors appeared to explain variation in incidence, only day of the week appears to be important, with the earlier part of the week yielding a highly statistically significant increase in the relative incidence of trauma admissions. For both paediatric and total admissions, a number of factors appear important, including maximum and minimum temperatures, hours of sunshine, day of the week and month of the year. Daily rainfall, significant weather and whether the day was a school day or school holiday did not appear to be important on univariate analysis. CONCLUSION: Trauma admissions are related to both weather and temporal factors. This may have implications both in terms of prevention and in planning of care provision in trauma units.     

Effect of nitrogen dioxide and ozone on the risk of dying in patients with severe asthma

BACKGROUND: A study was performed to assess the acute association between air pollution, pollen and spores, and mortality in a population based cohort of subjects with asthma recruited from emergency room admissions for an asthma exacerbation using a case crossover design. METHODS: Patients in Barcelona aged over 14 years who died during the period 1985-95 who had visited the emergency department of one of the four largest hospitals in the city for asthma during 1985-9 were included in the study (a total of 467 men and 611 women). Deaths were identified by record linkage of the cohort individuals with the Catalonia mortality registry. Causes of death were based on the underlying cause on the death certificate. Air pollution, pollen and spore levels were measured at the city monitoring stations which provide an average for the entire city. RESULTS: Nitrogen dioxide was associated with mortality for all causes of death (adjusted odds ratio (OR) for an increase of the interquartile range = 1.50, 95% confidence interval (CI) 1.09 to 2.64) in asthmatic patients with more than one emergency room admission for asthma. The association was particularly strong for respiratory causes (OR 1.63, 95% CI 0.93 to 2.86). Ozone also increased the risk of death in asthmatic patients (OR 1.90, 95% CI 1.09 to 3.30) during spring and summer. The association with particles, pollen, and spores was not significant, and no interactions between air pollutants and pollen and spores were found. CONCLUSION: Nitrogen dioxide and ozone may exacerbate severe asthma and even cause death among asthmatic subjects.     

Short-term association between air pollution and emergency room visits for asthma in Barcelona.

BACKGROUND--Several studies have assessed the association between urban air pollutants and hospital admissions or emergency room visits for asthma with inconsistent results. The objective of this study was to assess the relation between levels of black smoke, sulphur dioxide, nitrogen dioxide, and ozone and adult emergency room visits for asthma in Barcelona, Spain during the five year period 1985-9. METHODS--The daily number of emergency room visits for asthma was obtained from a register of respiratory emergencies designed to study the asthma outbreaks occurring in Barcelona. The association between asthma visits and levels of pollutants was assessed separately for summers and winters with Poisson regression models controlling for meteorological and time related variables. RESULTS--Black smoke was associated with asthma visits in summer but not in winter. The relative risk (RR) of asthma visits for a 25 micrograms/m3 increase of current day concentrations of black smoke was 1.082 (95% CI 1.011 to 1.157). The mean current and previous three day levels of black smoke led to a stronger association (RR = 1.114 (95% CI 1.010 to 1.160). In addition, nitrogen dioxide was associated with asthma visits in both summer (RR = 1.045, 95% CI 1.009 to 1.081) and winter (RR = 1.056, 95% CI 1.011 to 1.104). These associations were slightly higher for the previous day's level of nitrogen dioxide. No associations were found for sulphur dioxide or for ozone. CONCLUSIONS--This study provides further evidence of the effect of particulate pollution on asthma, and it suggests that nitrogen dioxide may have a role in the exacerbation of bronchial asthma in adults.     

Association between air pollution and general practitioner visits for respiratory diseases in Hong Kong

BACKGROUND: Few studies have explored the relation between air pollution and general practitioner (GP) consultations in Asia. Clinic attendance data from a network of GPs were studied, and the relationship between daily GP consultations for upper respiratory tract infections (URTI) and non-URTI respiratory diseases and daily air pollutant concentrations measured in their respective districts was examined. METHODS: A time series study was performed in 2000-2002 using data on daily patient consultations in 13 GP clinics distributed over eight districts. A Poisson regression model was constructed using the generalised additive model approach for each GP clinic, and associations with daily numbers of first visits for URTI were sought for daily concentrations of the following air pollutants: SO(2), NO(2), O(3), PM(10,) and PM(2.5). A summary relative risk of first visits to the GP for URTI per unit increase in concentration for each air pollutant was derived using a random effect model. First visits for non-URTI respiratory diseases were analysed in three GP clinics. RESULTS: Significant associations were observed between first visits for URTI and an increase in the concentrations of NO(2), O(3), PM(10), and PM(2.5). The excess risk was highest for NO(2) (3.0%), followed by O(3) (2.5%), PM(2.5) (2.1%), and PM(10) (2.0%). Similar associations with these air pollutants were found for non-URTI respiratory diseases. CONCLUSIONS: These results provide further evidence that air pollution contributes to GP visits for URTI and non-URTI respiratory diseases in the community.     

Indoor air pollution in developing countries and acute lower respiratory infections in children

BACKGROUND: A critical review was conducted of the quantitative literature linking indoor air pollution from household use of biomass fuels with acute respiratory infections in young children, which is focused on, but not confined to, acute lower respiratory infection and pneumonia in children under two years in less developed countries. Biomass in the form of wood, crop residues, and animal dung is used in more than two fifths of the world's households as the principal fuel. METHODS: Medline and other electronic databases were used, but it was also necessary to secure literature from colleagues in less developed countries where not all publications are yet internationally indexed. RESULTS: The studies of indoor air pollution from household biomass fuels are reasonably consistent and, as a group, show a strong significant increase in risk for exposed young children compared with those living in households using cleaner fuels or being otherwise less exposed. Not all studies were able to adjust for confounders, but most of those that did so found that strong and significant risks remained. CONCLUSIONS: It seems that the relative risks are likely to be significant for the exposures considered here. Since acute lower respiratory infection is the chief cause of death in children in less developed countries, and exacts a larger burden of disease than any other disease category for the world population, even small additional risks due to such a ubiquitous exposure as air pollution have important public health implications. In the case of indoor air pollution in households using biomass fuels, the risks also seem to be fairly strong, presumably because of the high daily concentrations of pollutants found in such settings and the large amount of time young children spend with their mothers doing household cooking. Given the large vulnerable populations at risk, there is an urgent need to conduct randomised trials to increase confidence in the cause-effect relationship, to quantify the risk more precisely, to determine the degree of reduction in exposure required to significantly improve health, and to establish the effectiveness of interventions.     

A paediatric canopy system for aerosol administration and minimized environmental pollution

Background: A canopy system for ribavirin aerosol administration to infants has been developed in order to improve the control of aerosol treatment, facilitate access to the infant and minimize environmental pollution. The system comprises a transparent canopy, fitted with four sealable apertures. An evacuation flow that is 3 1/min higher than the gas supply was anticipated to prevent aerosol leakage from the canopy.
Method: In a clinical evaluation , 10 infants with body weights of 1.8-7.1 kg were placed inside the canopy during 1 hour of simulated treatment. The temperature, relative humidity and carbon dioxide concentration within the canopy were measured repeatedly to study the stability of these variables and their dependence on body weight. Infant body temperature, skin temperature and the respiratory frequency were measured. In a laboratory evaluation , aerosol leakage was studied using an ambient air admixture procedure and smoke tests. The sound level inside the canopy was measured.
Results: All physical variables inside the canopy remained stable. The sound level was 52 dBA. The carbon dioxide concentration (1000–3900 PPM) correlated with infant body weight ( P <0.001), as did canopy temperature (25.1–29.6°C, P <0.05). The relative humidity was 52–88%. Infant body temperatures were not influenced. The respiratory frequency decreased by 13% ( P <0.01). No aerosol leakage was observed. Conclusion: The canopy system facilitates a controlled aerosol therapy with good infant surveillance and accessibility, a minimum of environmental pollution and a comfortable physical environment without apparent risks of carbon dioxide rebreathing or cooling stress at body weights of 1.8-7.1 kg.     

Analgesic and respiratory effect of nalbuphine and pethidine for adenotonsillectomy in children with obstructive sleep disorder

Opioids may depress respiration and contribute to airway obstruction after adenotonsillectomy for obstructive sleep disorder. We compared the respiratory and analgesic effects of nalbuphine, which has a ceiling effect for respiratory depression, and pethidine in 90 children (aged 2–12 years) with a history of obstructive sleep disorder undergoing adenotonsillectomy. Children were scored for their obstructive sleep disorder history and were randomly allocated to receive intravenously at induction of anaesthesia either nalbuphine 0.1 mg.kg⁻¹ (group N) or pethidine 1 mg.kg⁻¹ (group P). End-tidal carbon dioxide was measured in the recovery period using a nasopharyngeal catheter and oxygen saturation whilst breathing air; pain and sedation scores were recorded for 6 h postoperatively. Both groups were similar with respect to the demographic data and respiratory measurements: mean (SD) oxygen saturation on air in the recovery area (96.2% (1.2) vs. 96.5% (1.1) in group N and P, respectively) and mean (SD) end-tidal carbon dioxide (46.4 (5.5) mmHg vs. 47.7 (4) mmHg in group N and P, respectively). High obstructive sleep disorder score, history of apnoea, hyperactivity and loud snoring were found to be the best predictors of early postoperative oxygen desaturation in both groups.     

Case-control study of hospital admission with asthma in children aged 5-14 years: relation with road traffic in north west London

BACKGROUND: Evidence for an association between road traffic pollution and asthma is inconclusive. We report a case-control study of hospital admissions for asthma and respiratory illness among children aged 5-14 in relation to proxy markers of traffic related pollution. METHODS: The study was based on routine hospital admissions data in 1992/3 and 1993/4 for North Thames (West) health region within the M25 motorway. Cases were defined as emergency admissions for asthma (n = 1380) or all respiratory illness including asthma (n = 2131), and controls (n = 5703) were other emergency admissions excluding accidents. Cases and controls were compared with respect to distance of residence from nearest main road or roads with peak hour traffic >1000 vehicles and traffic volume within 150 m of residence, obtained by Geographical Information System techniques. Statistical analysis included adjustment for age, sex, admitting hospital, and a deprivation score for the census enumeration district of residence. RESULTS: Adjusted odds ratios of hospital admission for asthma and respiratory illness for children living within 150 m of a main road compared with those living further away were, respectively, 0.93 (95% CI 0.82 to 1.06) and 1.02 (95% CI 0.92 to 1.14). CONCLUSIONS: This study showed no association between risk of hospital admission for asthma or respiratory illness among children aged 5-14 and proxy markers of road traffic pollution.     

Hospital admission rates for asthma and respiratory disease in the West Midlands: their relationship to air pollution levels.

BACKGROUND--A study was undertaken to determine the relationship between hospital admissions for asthma and all respiratory conditions in electoral wards in the West Midlands and ambient levels of smoke, sulphur dioxide, and nitrogen dioxide, and to establish whether the relationship is independent of social deprivation and ethnicity, and is different for young children and older individuals. METHODS--Data on hospital admissions for acute respiratory conditions were obtained by electoral ward from the West Midlands Regional Health Authority Information Department Körner inpatient data including asthma (ICD 493) and all acute respiratory disease (466, 480-486, 490-496) for the period April 1988 to March 1990. The population for each electoral ward, percentage of ward population that was from non-white ethnic groups, and Townsend deprivation score were all calculated from 1991 census information. Data on smoke and sulphur dioxide (SO2) levels were obtained for 24 wards in Birmingham, Coventry, Wolverhampton, Dudley, Stafford, and Burton-on-Trent, and on nitrogen dioxide (NO2) levels from 39 wards in the same local authority areas. All were background urban sites and most participated in the Warren Spring national quality control programme for SO2 and smoke monitoring. Indirect age-sex standardised hospitalisation rates (SHR) for all respiratory conditions and asthma were calculated using the 1991 rates for the West Midlands RHA as the standard. Multivariate regression models were used to assess the relationship between individual pollutants and the SHR. The Townsend score and percentage of the population from non-white ethnic groups were included in all models to adjust for ethnicity and socioeconomic deprivation. RESULTS--The SHR for asthma varied almost fourfold across the region, and all respiratory SHR showed more than three fold variation. Bivariate regression revealed both Townsend score and percentage of non-white individuals to be associated with SHR for asthma and all respiratory conditions at all ages, but not for children under 5 years. NO2 was associated with hospital admission rates for all ages including children under 5. SO2 and smoke were not associated with hospital admissions. Multivariate analysis including Townsend score and percentage of non-white subjects in the model revealed that NO2 was associated with hospital admission rates for all respiratory conditions only for children under 5. The Townsend score was associated with SHR for all respiratory conditions, and both the Townsend score and percentage of non-white subjects were associated with SHR for asthma in children under 5 in two of three models. The association between SHR for asthma and percentage of non-white subjects was negative. CONCLUSIONS--Socioeconomic deprivation, as measured by the Townsend score, is a significant predictor of hospital admission rates for respiratory disease in older individuals, and both the percentage of non-white subjects and the Townsend score are significant predictors of hospital admission rates for asthma in children. After correction for socioeconomic deprivation and ethnicity, background urban NO2 levels in the ward of residence are significantly associated with standardised hospital admission rates for all respiratory disease in children under 5. This may represent a causal effect of NO2 on the respiratory health of children, or the effect of confounding factors not corrected by use of the Townsend score.