Emergency room visits of asthmatic children, relation to air pollution, weather, and airborne allergens

The relationship of air pollution to ED visits for asthma differ between children and adults

The purpose of this study was to evaluate the relationship between air pollution and asthma exacerbation in children and adults. Pearson analysis was used to establish correlations between air pollutants-sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, and particles with an aerodynamic diameter of 10 microm or less (PM(10))--and ED visits for asthma in 2004. Among children, there were significant positive correlations between nitrogen dioxide (r = 0.72), carbon monoxide (r = 0.65), and PM(10) (r = 0.63) and ED visits for asthma. Among adults, only weakly positive, non significant correlations between all air pollution measures and ED visits for asthma were found. This study suggests that air pollution plays a role in acute exacerbation of asthma in children but not in adults.

Seasonality in pediatric asthma admissions: the role of climate and environmental factors

BACKGROUND

Population-based data from Taiwan are used to examine seasonality in pediatric asthma admissions (proxy for asthma exacerbations) and associations with air pollutants and climatic factors. Monthly admission rates per 100,000 population, classified into three age groups, 0 approximately 2, 2 approximately 5, and 6 approximately 14 years (calculated from a total of 27,275 hospitalizations during 1998-2001) were subjected to autoregressive integrated moving average (ARIMA) modeling to examine seasonality. Spearman rank correlations were used to examine associations with criterion air pollutants (PM(10), SO(2), CO, O(3), NO(2)) and meteorological factors (ambient temperature, relative humidity, atmospheric pressure, rainfall, and sunshine hours).

RESULTS

Both seasonality and associations with air pollutants and climate factors vary by age group. Among under-twos, the rates are lowest in January-February and highest in November, with a trough in June-July. Among preschoolers, the rates are lowest in June-July and highest in November, with two upsurges in August and March. Among school-goers, admission rates are lowest during June-August, with upsurges in March and September. The number of weather and pollutant predictors increases with age. Among under-twos, only two factors, PM(10) and rainfall, significantly predict admissions. For preschoolers, five factors (PM(10), CO, O(3), temperature, and pressure), and for school-goers, all air pollutants except NO(2,) and all climatic factors except rainfall are significant.

CONCLUSION

Seasonality in pediatric asthma admissions vary by age in a subtropical island setting.

Seasonality in adult asthma admissions, air pollutant levels, and climate: a population-based study

OBJECTIVE AND BACKGROUND

Most studies of asthma seasonal variations have not examined associations of environmental risk factors and climatic changes associated with seasonality in asthma hospitalizations. This study used population-based data to examine seasonality in asthma admissions and the associated seasonality in levels of air pollutants and climatic factors during a 4-year period in Taiwan.

METHODS

A total of 126,671 asthma hospitalizations in Taiwan during 1998-2001 operationalized as monthly admissions per 100,000 population and monthly mean levels of criterion air pollutants and meteorological factors were subjected to Auto-Regressive Integrated Moving Average to test for seasonality and association between asthma admission rates and the pollutant and climatic factor levels. Owing to significant differences in seasonality between pediatric and adult age groups, this study was limited to 99,591 adult asthma cases to examine the seasonality issue as related to the criterion air pollutants and climatic factors using Spearman rank correlations.

RESULTS

Seasonal trends showed a hospitalization peak in January through March and a sharp decline beginning in April to a trough in June for both sexes. Seasonal variations in adult asthma admissions were significantly positively correlated with levels of PM10, SO2, CO, NO2, and atmospheric pressure and negatively correlated with temperature and hours of sunshine.

CONCLUSIONS

Adult asthma hospitalization propensity is highest in spring and is significantly correlated with air pollution and climate. Air quality control programs and early public warning systems on pollution and atmospheric factors are needed to enable predisposed individuals and their physicians to preempt attacks through primary and secondary preventive measures.

Association of weather conditions with childhood admissions for wheezy bronchitis or asthma in Athens

BACKGROUND

The association between asthma morbidity and meteorological conditions is well documented, but it is not clear to what extent more specific meteorological variables are implicated.

OBJECTIVES

This study was aiming to investigate whether there is any association between specific meteorological conditions and the seasonal variation and the rate of asthma admissions among children in Athens.

METHODS

Data were obtained retrospectively from hospital registries of the three main Children's Hospitals in Athens during a 23-year period (1978-2000). The meteorological database consisted of mean monthly values of eight meteorological variables. The whole period studied was divided into three time periods: 1978-1987, 1988-1993 and 1994-2000.

RESULTS

A clear seasonal trend with a permanent pattern was detected. There were more monthly asthma admissions in winter-spring and autumn for younger children, as well as a lower peak in winter and autumn and a major one in May for older children, without significant differences in between the three time periods. The results of a multiple regression analysis revealed that relative humidity and atmospheric pressure were predictors of up to 56.7% (1988-1993) and 59.2% (1994-2000) monthly asthma admissions among younger children. No relation of the time trend in asthma admissions during the periods studied for any age group with any of the meteorological variables was detected.

CONCLUSIONS

Our results indicate a constant seasonal variability in asthma admissions among children in Athens, whereas relative humidity and atmospheric pressure are the more implicated meteorological variables for younger asthmatic children.

Temporal associations between daily counts of fungal spores and asthma exacerbations

BACKGROUND

Outdoor aeroallergens are one of a number of environmental factors thought to precipitate asthma exacerbations.

AIMS

To investigate the short term associations between daily fungal spore concentrations and indicators of daily asthma exacerbations in a large urban population.

METHODS

Daily counts of visits for asthma to family physicians and hospital accident and emergency (A&E) departments and emergency hospital admissions in London 1992-93 were compiled. Daily concentrations of fungal spores (30 species), daily average temperature, humidity, and concentrations of pollen and outdoor air pollution were also compiled. The analysis was restricted to the period when fungal spores were most prevalent (June to mid October). Non-parametric regression time series methods were used to assess associations controlling for seasonality, day of week, and meteorological factors. The sensitivity of the findings to the inclusion of pollen and air pollution into the models was also assessed.

RESULTS

In children aged 0-14 years the relative risks for increases in the number of A&E visits and hospital admissions associated with changes in fungal spore concentrations from the lower to upper quartiles were 1.06 (95% CI 0.94 to 1.18) and 1.07 (0.97 to 1.19) respectively. The addition of pollen or air pollutants had little impact on the observed associations. A number of individual spore taxa, in particular Alternaria, Epicoccum, Agrocybe, Mildews, and both coloured and colourless Basidiospores and Ascospores, were associated with increases in the number of emergency visits and hospital admissions for asthma, although the precision of these estimates were low. No evidence was found for associations in adults.

CONCLUSIONS

Fungal spore concentrations may provoke or exacerbate asthma attacks in children resulting in visits to A&E departments and emergency hospital admissions. These findings were unlikely to be due to confounding by other environmental factors. The associations were comparable to those observed for ambient air pollution from similarly designed studies.

Effects of nitrogen dioxide on allergic airway responses in subjects with asthma

OBJECTIVE

We sought to determine whether nitrogen dioxide (NO2) can enhance airway inflammation after allergen challenge in asthmatic subjects.

METHODS

Fifteen house-dust-mite (HDM)-sensitive asthmatic subjects were exposed for 3 hours to filtered air or 0.4 ppm NO2, followed by inhalational challenge with HDM allergen. Markers of inflammation were measured in sputum at 6 hours and 26 hours after allergen challenge.

RESULTS

After exposure to NO2, eosinophil concentration decreased significantly in the 6-hour postallergen sputum. No significant NO2-related difference was observed for other variables.

CONCLUSIONS

Our results suggest that, in most asthmatic individuals, multi-hour exposure to a high ambient concentration of NO2 does not enhance the inflammatory response to subsequent inhaled allergen as assessed by cell distribution in induced sputum. Because the decrease in airway eosinophils has been reported in previous animal studies, future research should be directed toward the mechanism of this effect.

The September epidemic of asthma hospitalization: school children as disease vectors

BACKGROUND

Viral infections are associated with the majority of asthma exacerbations in children and adults. Increased asthma hospitalization rates of children and adults, particularly in the early fall, have been observed to follow school vacations.

OBJECTIVE

We sought to determine the sequence of timing of September asthma hospitalization epidemics in children and adults and to determine whether school-age children are the primary source of transmission of agents that cause them.

METHODS

By using Canadian asthma hospital admission data from 1990 to 2002, we examined geographic variation in the timing of fall asthma epidemics and applied mathematical modeling to estimate their exact timing and magnitude in school-age children, preschool children, and adults, and relation to school return.

RESULTS

The September asthma hospitalization epidemic peak occurred in school-age children each year on average 17.7 (95% CI, 16.8-18.5) days after Labor Day. Similar epidemics of lesser magnitude were observed in preschool children peaking 1.7 (95% CI, 0.9-2.5; P<.001) days later, and in adults 6.3 (95% CI, 4.7-7.9; P<.001) days later than in school-age children. The epidemics peaked 4.2 (95% CI, 1.2-7.1; P<.001) days earlier in school-age children in northernmost compared with southernmost latitudes.

CONCLUSION

September epidemics of asthma hospitalizations in Canada have a precise relationship to school return after the summer vacation. It may be speculated that school-age children transmit the agents responsible for the epidemic to adults. Measures to improve asthma control and reduce transmission of infections should be directed at children with asthma before school return.

Environmental risk factors and allergic bronchial asthma

The prevalence of allergic respiratory diseases such as bronchial asthma has increased in recent years, especially in industrialized countries. A change in the genetic predisposition is an unlikely cause of the increase in allergic diseases because genetic changes in a population require several generations. Consequently, this increase may be explained by changes in environmental factors, including indoor and outdoor air pollution. Over the past two decades, there has been increasing interest in studies of air pollution and its effects on human health. Although the role played by outdoor pollutants in allergic sensitization of the airways has yet to be clarified, a body of evidence suggests that urbanization, with its high levels of vehicle emissions, and a westernized lifestyle are linked to the rising frequency of respiratory allergic diseases observed in most industrialized countries, and there is considerable evidence that asthmatic persons are at increased risk of developing asthma exacerbations with exposure to ozone, nitrogen dioxide, sulphur dioxide and inhalable particulate matter. However, it is not easy to evaluate the impact of air pollution on the timing of asthma exacerbations and on the prevalence of asthma in general. As concentrations of airborne allergens and air pollutants are frequently increased contemporaneously, an enhanced IgE-mediated response to aeroallergens and enhanced airway inflammation could account for the increasing frequency of allergic respiratory allergy and bronchial asthma. Pollinosis is frequently used to study the interrelationship between air pollution and respiratory allergy. Climatic factors (temperature, wind speed, humidity, thunderstorms, etc) can affect both components (biological and chemical) of this interaction. By attaching to the surface of pollen grains and of plant-derived particles of paucimicronic size, pollutants could modify not only the morphology of these antigen-carrying agents but also their allergenic potential. In addition, by inducing airway inflammation, which increases airway permeability, pollutants overcome the mucosal barrier and could be able to "prime" allergen-induced responses. There are also observations that a thunderstorm occurring during pollen season can induce severe asthma attacks in pollinosis patients. After rupture by thunderstorm, pollen grains may release part of their cytoplasmic content, including inhalable, allergen-carrying paucimicronic particles.

Sensitivity of exercise testing for asthma in adolescents is halved in the summer

STUDY OBJECTIVES

The exercise test is one of the most widely used challenge tests for asthma. It is not clear if the sensitivity of this test is lower when patients with asthma are not symptomatic. Since asthma activity is season dependent, with lower activity in the summer, we sought to determine if the percentage of positive exercise test results for asthma is lower in the summer as well.

DESIGN

In this retrospective study, the proportion of positive exercise test results for asthma during each of the four seasons of the year, over a 5-year period, was compared.

SETTING

The study was conducted at the pediatric respiratory clinic and pulmonary function laboratory of Shaare Zedek Medical Center.

PARTICIPANTS

The study group consisted of 532 consecutive patients, all 17 years of age, who were referred for exercise testing for evaluation of suspected asthma. All had normal baseline FEV1 levels, and none received maintenance asthma treatment.

MEASUREMENTS AND RESULTS

Spirometry was performed before and after a standard exercise regimen. A decrease of > or = 10% in FEV1 after exercise was considered positive; 141 patients (26%) had a positive test result. The percentage of positive results in the summer (July to September quartile) was 12.9%, less than half the percentage of positive results during any of the other three quartiles (January to March, 28.9%, p < 0.05; April to June, 30.6%, p < 0.05; October to December, 29.1%, p < 0.05).

CONCLUSIONS

This study shows that the percentage of positive exercise challenge test results in the summer is half that of any other season. It is likely that the lower percentage of positive results for asthma in the summer reflects the lower sensitivity of the test during this season due to decreased asthma activity. We suggest performing exercise challenge testing only when patients are symptomatic. Physicians caring for patients with symptoms suggestive of exercise-induced asthma whose exercise test results are negative while asymptomatic should consider repeat exercise testing when their patients are symptomatic.

A miniaturized active sampler for the assessment of personal exposure to nitrogen dioxide

A personalized, miniaturized air sampling system was evaluated to estimate the daily exposure of pediatric asthmatics to nitrogen dioxide (NO2). The lightweight device (170 g) uses a sampling pump connected to a solid sorbent tube containing triethanolamine (TEA)-impregnated molecular sieve. The pump is powered by a 9 V battery and samples air over a 24 h period at a collection rate of 0.100 L/min. After exposure, the solid sorbent is removed from the tubes for spectrophotometric analysis (Griess Assay). The lower detection limit of the overall method for NO2 is 11 microg/m3. The linearity, precision and accuracy of the sampler was evaluated. Different NO2 concentrations generated in the laboratory (range: 50 to 340 microg/m3) were simultaneously measured by the TEA tube samplers and colocated continuous chemiluminescent NO(x) analyzers (reference method). The coefficient of determination for the laboratory test derived from ordinary linear regression (OLR) was r2 = 0.99 (y(OLR) = 0.94 x -4.58) and the precision 3.6%. Further, ambient NO2 concentrations in the field (range: 10-120 microg/m3) were verified with continuous chemiluminescent monitors next to the active samplers. Re-weighted least squares analysis (RLS) based on the least median squares procedure (LMS) resulted in a correlation of r2 = 0.68 for a field comparison in Riverside, CA (y(RLS) = 1.01 x -0.94) and r2 = 0.92 in Los Angeles, CA (y(RLS) = 1.31 x -7.12). The precision of the TEA tube devices was 7.4% (at 20-60 microg/m3 NO2) under outdoor conditions. Data show that the performance of this small active sampling system was satisfactory for measuring environmental concentrations of NO2 under laboratory and field conditions. It is useful for personal monitoring of NO2 in environmental epidemiology studies where daily measurements are desired.

Childhood asthma hospitalizations and ambient air sulfur dioxide concentrations in Bronx County, New York

The association between asthma hospitalizations and ambient sulfur dioxide (SO2) concentrations was examined in a case-control study in Bronx County, New York. Cases comprised 2629 children aged 0-14 yr who were admitted to hospitals for asthma. There were 2236 controls who were admitted for reasons other than asthma. Daily ambient SO2 concentrations were categorized into quartiles of both average and maximum levels and various exposure windows (i.e., day of admission and 1-, 2-, and 3-d lags). Cases were exposed to higher daily average concentrations of SO2 than controls. The authors compared the highest exposure quartile with the lowest, and the odds ratios were 1.66, 1.90, 2.05, and 2.21 (all p < 0.01 for same-day, 1-, 2-, and 3-d lags, respectively), with a similar finding for daily SO2 maximum exposure. The results suggest a consistent positive association between SO2 exposure and hospitalizations for childhood asthma.

Recent trends in adolescent asthma

Asthma is a disability that can affect the quality of life of the adolescent going through a period with difficulty and often rebellion, but gentle care from the primary physician will guide the adolescent through this period. A worldwide increase in childhood asthma has been observed and recent data from the National Health Interview Survey-2003 in the United States showed an overall 12.5% of children under age 18 years, who ever had asthma diagnosed. This short communication reviews the recent U.S. findings with research on adolescent asthma in Israel, where a study from year 2000 found a higher percentage of ever had diagnosed asthma (13.7%).

Airborne particulates and asthma: a Maine case study

Maine currently has the second fastest growing asthma rate in the nation 9.4% of the adult population has asthma and one out of eight children is affected. The factors behind this increase are poorly understood, but previous reports suggest that biologically soluble metal ions from particulate matter (PM10) may play a role in asthma episodes. In an effort to study this issue, we first identified geographic and temporal trends in Maine asthma hospitalizations. Clinical data show a strong fall peak in asthma admissions with weaker peaks in January and May, and a summer low in asthma admissions. Asthma admissions are also higher in the cities than in the rural areas in Maine. We then analysed PM10 collected by the Maine Department of Environmental Protection in three different Maine locations in the years 2000 and 2001, at times when clinical asthma data showed peaks and during the summer low period. We also collected soil samples in the same locations. The PM10 and soils were analysed for 10 metals by acid extraction to determine total metal content and then with cell culture medium, DMEM/F12+CCS growth medium, to determine metal biosolubility. Our results showed that Mn, Cu, Pb, As, V, Ni and Al were present in the Maine PM samples. V, Ni and Pb showed seasonal variation, while the others were relatively constant throughout the year. Pb and Al did not appear to be soluble in the biological medium. There was also variation from location to location with the urban area showing the highest concentrations for most metals. Aluminium was present in the highest concentration in soil samples, followed by Mn and V. Only Cu was biologically available in soils. We determined from M/Al ratios that most of the PM10 did not originate from local crustal material.

Indoor exposures to air pollutants and allergens in the homes of asthmatic children in inner-city Baltimore

This paper presents indoor air pollutant concentrations and allergen levels collected from the homes of 100 Baltimore city asthmatic children participating in an asthma intervention trial. Particulate matter (PM), NO2, and O3 samples were collected over 72 h in the child's sleeping room. Time-resolved PM was also assessed using a portable direct-reading nephelometer. Dust allergen samples were collected from the child's bedroom, the family room, and the kitchen. The mean PM10 concentration, 56.5+/-40.7 microg/m3, is 25% higher than the PM2.5 concentration (N=90), 45.1+/-37.5 microg/m3. PM concentrations measured using a nephelometer are consistent and highly correlated with gravimetric estimates. Smoking households' average PM2.5 and PM10 concentrations are 33-54 microg/m3 greater than those of nonsmoking houses, with each cigarette smoked adding 1.0 microm/m3 to indoor PM2.5 and PM10 concentrations. Large percentages of NO2 and O3 samples, 25% and 75%, respectively, were below the limit of detection. The mean NO2 indoor concentration is 31.6+/-40.2 ppb, while the mean indoor O3 concentration in the ozone season was 3.3+/-7.7 ppb. The levels of allergens are similar to those found in other inner cities. Results presented in this paper indicate that asthmatic children in Baltimore are exposed to elevated allergens and indoor air pollutants. Understanding this combined insult may help to explain the differential asthma burden between inner-city and non-inner-city children.

The September epidemic of asthma exacerbations in children: a search for etiology

Background

Predictable peaks of asthma exacerbation requiring hospital treatment, of greatest magnitude in children and of uncertain etiology, occur globally after school returns.

Objective

We wished to determine whether asthmatic children requiring emergency department treatment for exacerbations after school return in September were more likely to have respiratory viruses present and less likely to have prescriptions for control medications than children with equally severe asthma not requiring emergent treatment.

Methods

Rates of viral detection and characteristics of asthma management in 57 (of 60) children age 5 to 15 years presenting to emergency departments with asthma in 2 communities in Canada between September 10 and 30, 2001, (cases) were compared with those in 157 age-matched volunteer children with asthma of comparable severity studied simultaneously (controls).

Results

Human picornaviruses were detected in 52% of cases and 29% of controls (P = .002) and viruses of any type in 62% of cases and 41% of controls (P = .011). Cases were less likely to have been prescribed controller medication (inhaled corticosteroid, 49% vs 85%; P < .0001; leukotriene receptor antagonist, 9% vs 21%; P = .04).

Conclusion

Respiratory viruses were detected in the majority of children presenting to emergency departments with asthma during the September epidemic of the disease and in a significant minority of children with asthma in the community. The latter were more likely to have anti-inflammatory medication prescriptions than children requiring emergent treatment. Such medication may reduce the risk of emergency department treatment for asthma during the September epidemic.

Clustering of allergic outcomes within families and households in areas endemic for helminth infections

BACKGROUND

Allergy and helminth infections share key immunological features in terms of Th2 responses. Although in industrialized countries clustering of allergic disorders within families has been frequently reported, such information is lacking from areas where helminth infections are endemic.

METHODS

A total of 466 subjects from 29 families and 112 households participated in this study. Filarial infection, skin test reactivity and IgE to mite as well as total IgE were measured in all samples. Clustering of the allergy-related outcomes due to genetic and household factors was tested.

RESULTS

Genetic factors contributed significantly to the clustering of total IgE and allergen-specific IgE, whereas only household factors contributed to the clustering of SPT positivity.

CONCLUSION

Similar to several studies conducted in western populations, total IgE and allergen-specific IgE are influenced by genetic factors in a population resident in a helminth endemic area. However, clustering of SPT positivity due to genetic factors was not significant in the current study raising the question of whether the presence of helminth infections may override genes that are associated with the expression of tissue reactivity to allergens in the west.

Air pollution, health, and socio-economic status: the effect of outdoor air quality on childhood asthma

This paper estimates the effect of air pollution on child hospitalizations for asthma using naturally occurring seasonal variations in pollution within zip codes. Of the pollutants considered, carbon monoxide (CO) has a significant effect on asthma for children ages 1-18: if 1998 pollution levels were at their 1992 levels, there would be a 5-14% increase in asthma admissions. Also, households respond to information about pollution with avoidance behavior, suggesting it is important to account for these endogenous responses when measuring the effect of pollution on health. Finally, the effect of pollution is greater for children of lower socio-economic status (SES), indicating that pollution is one potential mechanism by which SES affects health.

Trends in adolescent asthma in Israel

There has been observed a worldwide increase in childhood asthma and this short communication reviews current research on adolescent asthma in Israel. Several studies have found an overall asthma prevalence of 7.8% for Jewish children, 4.9% for Arab children and 3.7% for the total population, while 7.8% was found in Bedouin children in the south of Israel. For the 1980-1997 period for the 5-34 year age group the AMR (asthma mortality rate) per 100,000 was found to be 0.226 with no significant difference between Jews and Arabs. This is a decrease as a result of increase in the use of inhaled corticosteroids (ICS) and a better anti-inflammatory treatment.

Road-traffic pollution and asthma - using modelled exposure assessment for routine public health surveillance

Asthma is a common disease and appears to be increasing in prevalence. There is evidence linking air pollution, including that from road-traffic, with asthma. Road traffic is also on the increase. Routine surveillance of the impact of road-traffic pollution on asthma, and other diseases, would be useful in informing local and national government policy in terms of managing the environmental health risk.

Several methods for exposure assessment have been used in studies examining the association between asthma and road traffic pollution. These include comparing asthma prevalence in areas designated as high and low pollution areas, using distance from main roads as a proxy for exposure to road traffic pollution, using traffic counts to estimate exposure, using vehicular miles travelled and using modelling techniques. Although there are limitations to all these methods, the modelling approach has the advantage of incorporating several variables and may be used for prospective health impact assessment.

The modelling approach is already in routine use in the United Kingdom in support of the government's strategy for air quality management. Combining information from such models with routinely collected health data would form the basis of a routine public health surveillance system. Such a system would facilitate prospective health impact assessment, enabling policy decisions concerned with road-traffic to be made with knowledge of the potential implications. It would also allow systematic monitoring of the health impacts when the policy decisions and plans have been implemented.

Exposure levels of asthmatic children to allergens, endotoxins, and serine proteases in a tropical environment

A cross-sectional study was conducted in Bayamón, Puerto Rico, to identify and quantify indoor allergens, serine proteases, and bacterial endotoxin present in homes of asthmatic children. A total of 126 dust samples from houses were obtained from the entire mattress and bedside floor. Most of the patients had detectable levels of mite, cockroach, cat, and dog allergens. Mold allergens were found only in bedside floor dust samples. Mouse allergens were not detected. Forty-two percent, 36.5%, and 1.8% of the patients demonstrated exposures to sensitizing levels of mite, Bla g 1 and cat allergens, respectively. The percentage of patients exposed to high levels of allergens capable of triggering asthma symptoms was 33.3% and 26.4% for mite and Bla g 1 allergens. Only dog allergen, bacterial endotoxin, elastase, and trypsin were associated with asthma symptoms. Eighty-nine percent of the asthmatic children were exposed to endotoxin concentrations greater than 100 EU/mg dust, and more than half of the patients were exposed to high levels of serine proteases. Our study indicates that indoor concentrations of allergens traditionally associated with asthma symptoms and severity may not be applicable in tropical environments and highly ventilated households. In fact, in the study population, endotoxins, dog allergen, and serine proteases may play a dominant role in the induction of asthma symptoms.

Non-linear short-term effects of airborne pollen levels with allergenic capacity on asthma emergency room admissions in Madrid, Spain

BACKGROUND

Several time-series studies have shown positive associations between pollen levels and asthma morbidity. However, few studies have included air pollution as a potential confounder when examining this relationship, and they have only done so on a linear basis.

OBJECTIVE

To investigate the potential non-linear short-term effects of the types of pollen with allergenic capacity across the whole range of exposure on the daily number of asthma-related hospital emergencies in Madrid for the period 1995-1998.

METHODS

Data were collected on the daily number of asthma emergency room admissions and daily average levels of major types of pollen with allergenic capacity: Olea, Plantago, Poaceae and Urticaceae. We used Poisson regression with generalized additive models, controlling for trend and seasonality, meteorological variables, acute respiratory infections and air pollutants. To study the non-linear effect of pollen levels on asthma emergency room admissions, pollens were categorized into five groups defined on the basis of their respective distributions.

RESULTS

The strongest associations were registered in respect of a lag of 1 day for Urticaceae, a lag of 2 days for Plantago, and a day lag of 3 days for Poaceae. Adjustment for the different types of pollen failed to result in major changes. Non-linearities were evident for pollen levels. The greatest increase in risk vs. the reference category (minimum value - 50th percentile) was observed for the categories between the 95th and 99th percentiles, with increases of 32.0% for Plantago, 32.2% for Poaceae and 24.6% for Urticaceae, and between the 99th percentile and the maximum value, with increases of 31.3%, 78.7% and 49.8%, respectively. Olea was not related with asthma emergency room admissions.

CONCLUSIONS

Pollens with allergenic capacity in Madrid are positively associated with asthma-related hospital emergencies. These associations remain stable when simultaneous adjustment is made for the four types of pollen and for air pollutants and meteorological variables. In terms of non-linear effects, Poaceae register the strongest association with asthma emergency room admissions.

Dampness in buildings as a risk factor for health effects, EUROEXPO: a multidisciplinary review of the literature (1998-2000) on dampness and mite exposure in buildings and health effects

The scientific literature on health effects from dampness in buildings, including mite exposure over the period 1998-2000 has been reviewed by an European group (EUROEXPO) of eight scientists in experience from medicine, epidemiology, toxicology and engineering. Forty studies deemed relevant have been the foundation for the conclusions. Dampness in buildings is a risk factor for health effects among atopics and non-atopics both in domestic and in public environments. However, the literature is not conclusive in respect of causative agents, e.g. mites, microbiological agents and organic chemicals from degraded building materials. There is a strong need for more multidisciplinary studies including expertise from all relevant areas. A general conclusion from the work was that there is a strong need for multidisciplinary reviews in scientific journals of articles dealing with associations between indoor environmental factors and health effects.

PRACTICAL IMPLICATIONS

There is good evidence for a true association between dampness in buildings and health. As the causative factors behind this association are not known, the main focus in practical investigations should be on finding out and remediate the reasons for the humidity problem.

Outdoor air pollution and asthma

PURPOSE OF REVIEW

The relation between outdoor air pollution and asthma has always been a major focus of research. The evidence that current levels of air pollution in many countries result in increased morbidity and mortality is fairly consistent. With rapid urbanization in many communities, traffic exhausts have become the major source of pollution, and many recent research studies have attempted to investigate the detrimental effects of this type of pollution. This paper reviews the recent evidence of the possible detrimental effects of ambient air pollution on the inception and morbidity of asthma.

RECENT FINDINGS

Traffic related pollution has been confirmed in both cross-sectional and longitudinal studies to be associated with increased asthma morbidity and cardiopulmonary mortality. There is also evidence that pollutants such as ozone and traffic exhausts may be responsible for new incident cases of asthma. Among the particulate pollution, research investigating the ultrafine particles and the bacterial components suggested that these particles may have important role in asthma morbidity.

SUMMARY

More research studies are needed to reveal how various air pollutants may interact with the host systems, such as the immune system, leading to increased morbidity in susceptible individuals. Reduction of the current levels of ambient air pollution should be an integral part of the overall effort in minimizing asthma morbidity or mortality in the community.

Influence of climate factors on emergency visits for childhood asthma attack

BACKGROUND

Asthma attack shows strong seasonality. The purpose of the present study was to quantify the contribution of climate variables and other seasonal factors on the incidence of emergency visits for childhood asthma in Tokyo, Japan.

METHODS

The number of children who visited emergency rooms at Jikei university hospitals in Tokyo during 1998-2002 (5559 visits) was retrieved retrospectively from files from the Department of Pediatrics, and compared with 45 climate parameters from the Meteorological Agency using multiple regression models with a stepwise backward elimination approach.

RESULTS

The number of visits (3.7 +/- 3.1) per night increased significantly when climate conditions showed a rapid decrease from higher barometric pressure, from higher air temperature and from higher humidity, as well as lower wind speed. The best-fit model demonstrated that a 22% variation in the number of visits was explained by a linear relationship with 12 climate variables, which increased to 36% after adjusting for calendar month and day of the week. Moreover, when the number of asthma visits was cut off at nine per night, the area under the receiver operator characteristics curve was 0.91 (95% CI: 0.89-0.94) in the multiple logistic regression model using the same variables.

CONCLUSIONS

These results suggest that these models might quantify contributions of specific climate conditions and other seasonal factors on the number of emergency visits per night for childhood asthma attack in Tokyo, Japan.

Interfacial phospholipids inhibit ozone-reactive absorption-mediated cytotoxicity in vitro

The intrapulmonary distribution of inhaled ozone (O(3)) and induction of site-specific cell injury are related to complex interactions among airflow patterns, local gas-phase concentrations, and the rates of O(3) flux into, and reaction and diffusion within, the epithelial lining fluid (ELF). Recent studies demonstrated that interfacial phospholipid films appreciably inhibited NO(2) absorption. Because surface-active phospholipids are present on alveolar and airway interfaces, we investigated the effects of interfacial films on O(3)-reactive absorption and acute cell injury. Compressed films of dipalmitoyl-glycero-3-phosphocholine (DPPC) and rat lung lavage lipids significantly reduced O(3)-reactive absorption by ascorbic acid, reduced glutathione, and uric acid. Conversely, unsaturated phosphatidylcholine films did not inhibit O(3) absorption. We evaluated O(3)-mediated cell injury using a human lung fibroblast cell culture system, an intermittent tilting exposure regimen to produce a thin covering layer, and nuclear fluorochrome permeability. Exposure produced negligible injury in cells covered with MEM. However, addition of AH(2) produced appreciable (<50%) cell injury. Film spreading of DPPC monolayers necessitated the use of untilted regimens. Induction of acute cell injury in untilted cultures required both AH(2) plus very high O(3) concentrations. Addition of DPPC films significantly reduced cell injury. We conclude that acute cell injury likely results from O(3) reaction with ELF substrates. Furthermore, interfacial films of surface-active, saturated phospholipids reduce the local dose of O(3)-derived reaction products. Finally, because O(3) local dose and tissue damage likely correlate, we propose that interfacial phospholipids may modulate intrapulmonary distribution of inhaled O(3) and the extent of site-specific cell injury.

Factors associated with emergency department use in asthma: acute care interventions improving chronic disease outcomes

OBJECTIVE

To provide a literature review of the factors associated with childhood asthma-related emergency department (ED) visits and to identify elements of effective ED interventions that reduce the frequency of childhood ED visits while increasing primary health care utilization.

DATA SOURCE

English Medline articles from 1990 that cross-referenced with the terms asthma, emergency, intervention, pediatric, and/or acute care. Experts in the field of allergy and asthma were also consulted.

STUDY SELECTION

Childhood asthma interventions in the ED.

RESULTS

Factors associated with childhood asthma-related ED visits include being impoverished, being exposed to allergens, receiving Medicaid or lacking insurance, being noncompliant with self-management skills, and having an African-American heritage. Other minorities may also be at risk, but further investigation is required to determine the extent. Attempts to link the patient to primary health care by the ED staff resulted in increased adherence to followup care.

CONCLUSIONS

The ED provides an opportunity to help patients and families deal with asthma to improve their quality of life. Further, current studies demonstrate that the ED is an appropriate setting for an intervention that links the patient back to the primary health care provider. More research is needed on the appropriate educational messages to be delivered in ED. Also, barriers to followup care and regular use of a primary health care provider need to be identified so that future intervention designs can address these issues.

Relationship of outdoor air quality to pediatric asthma exacerbations

BACKGROUND

Although exposure to outdoor air pollutants has been shown to be associated with exacerbations of asthma, there are relatively few admissions for asthma to Cincinnati Children's Hospital, Cincinnati, OH during the summer months when air quality tends to be worst.

OBJECTIVE

The objective of this study was to determine the relationship of outdoor air quality parameters to asthma exacerbations in children.

METHODS

The number of emergency room visits and hospitalizations for asthma were determined by review of emergency department logs and the hospital computer database. Outdoor air concentrations of ozone, particulates of < 10 microm diameter (PM-10), pollens, and fungal spores were obtained from the Hamilton County Department of Environmental Services. Multiple regression analysis was performed, looking for relationships between the daily number of asthma visits and the air quality data for the same day and for 1 through 5 days before the visits.

RESULTS

A significant association was found between the number of asthma visits and the daily pollen count (P = 0.014, SE = 0.001). The effect was stronger for visits 1, 2, and 3 days after the pollen count (P < 0.001 for pollen count lagged 3 days). High PM-10 counts were synergistic with the pollen count as a predictor of asthma visits. There was no association between asthma visits and the ozone concentration or fungal spore count.

CONCLUSIONS

Exacerbations of asthma severe enough to require visits to the hospital were associated with elevated concentrations of airborne pollens and particulates, with a significant delayed effect. Ozone, in the concentrations measured here, was not a risk factor for severe asthma exacerbations in children.

Temporal relationship between air pollution and hospital admissions for asthmatic children in Hong Kong

BACKGROUND

Many epidemiological studies have shown positive association between respiratory health and current levels of outdoor air pollution in Europe and America.

OBJECTIVE

The aim of this study was to investigate the association between air pollution and the number of childhood admissions for asthma in Hong Kong.

METHODS

Daily counts of childhood admission for asthma to a large teaching Hospital were obtained from the computerized database for the period 1993-1994. A Poisson regression allowing for seasonal patterns and meteorological conditions was used to assess the associations between the number of Hospital admissions and the three pollutants: nitrogen dioxide, sulphur dioxide and inhalable particles (measured as PM10, particles < 10 microm in aerodynamic diameter).

RESULTS

A total of 1217 children under 15 years of age were admitted for asthma during the study period. The calculated annual hospitalization rates were 283 and 178 per 100 000 for boys and girls, respectively. The mean PM10, NO2 and SO2 levels were 44.1 microg/m3, 43.3 microg/m3, and 12.2 microg/m3, respectively. Daily admission for asthma increased significantly with increasing ambient level of nitrogen dioxide (relative risk (RR) = 1.08 per 10 microg/m3 increase), sulphur dioxide (RR = 1.06) and inhalable particles (RR = 1.03). No association was found between hospital admission and humidity, temperature or atmospheric pressure.

CONCLUSION

This is the first daily time series study of childhood admissions for asthma and air pollution in Hong Kong. The results support that current levels of air pollution contribute to the respiratory morbidity in asthmatic children in Hong Kong.

Carbon monoxide attenuates aeroallergen-induced inflammation in mice

Carbon monoxide (CO) generated by catalysis of heme by heme oxygenase is increased in the exhaled air of asthmatic patients. Based on recent studies demonstrating that asthma is an inflammatory disease associated with increased oxidants and that CO confers cytoprotection in oxidant-induced lung injury and inflammation, we sought to better understand the functional role of CO in asthma by using an aeroallergen model. Mice were sensitized to ovalbumin, challenged with aerosolized ovalbumin, and maintained in either CO (250 parts/million) or room air for 48 h. The differential effects of CO on bronchoalveolar lavage (BAL) fluid cell types were observed, with a marked attenuation of BAL fluid eosinophils in the CO-treated animals at 24 and 48 h. A marked reduction of the proinflammatory cytokine interleukin-5 was observed in the CO-treated mice, with no significant changes for other proinflammatory cytokines. These differential effects of CO were also observed with leukotrienes (LTs) and prostaglandins in that CO significantly decreased BAL fluid PGE2, and LTB4 but exerted negligible effect on thromboxane B2 or LTC4/D4/E4. Our data suggest a putative immunoregulatory role for CO in aeroallergen-induced inflammation in mice.

The role of outdoor air pollution and climatic changes on the rising trends in respiratory allergy

Evidence suggests that allergic respiratory diseases such as hay fever and bronchial asthma have become more common world-wide in the last two decades, and the reasons for this increase are still largely unknown. A major responsible factor could be outdoor air pollution, derived from cars and other vehicles. Studies have demonstrated that urbanization and high levels of vehicle emissions and westernized lifestyle is correlated with the increasing frequency of pollen-induced respiratory allergy. People who live in urban areas tend to be more affected by pollen-induced respiratory allergy than those from of rural areas. Pollen allergy has been one of the most frequent models used to study the interrelationship between air pollution and respiratory allergic diseases. Pollen grains or plant-derived paucimicronic components carry allergens that can produce allergic symptoms. They may also interact with air pollution (particulate matter, ozone) in producing these effects. There is evidence that air pollutants may promote airway sensitization by modulating the allergenicity of airborne allergens. Furthermore, airway mucosal damage and impaired mucociliary clearance induced by air pollution may facilitate the access of inhaled allergens to the cells of the immune system. In addition, vegetation reacts with air pollution and environmental conditions and influence the plant allergenicity. Several factors influence this interaction, including type of air pollutants, plant species, nutrient balance, climatic factors, degree of airway sensitization and hyperresponsiveness of exposed subjects.

[Impact in the quality of health care and cost-effectiveness analysis of the reform of an emergency medicine service]

BACKGROUND

To determine the effects that the reform of an emergency department (ED) have on efficacy, health care quality and efficiency.

MATERIAL AND METHOD

Reforms consisted of 50% and 34% increases in structural and human resources, respectively. Roles of each ED member were redetermined, new assistance pathways were implemented, and the relationship between ED and the remaining hospital departments was reassessed. As efficacy markers, we determined the number of patients waiting to be attended (Pesp), the waiting time of patients to receive medical assistance (T(esp)),and the total waiting time of patients staying in the ED (T(total)). As health-care quality markers, we determined the percentage of patients leaving ED without having been visited by a physician(IPNV), the percentage of patients who were visited again (IPR),and the percentage of mortality (IPF). We also quantified the number of visits to the ED. All these data were obtained daily over 3 weeks, before (February 1999) and after (February 2000)the reforms. Effectiveness was estimated from the ratio P(total)/T(esp)(E1) and P(total)/P(esp) (E2). Costs were recorded for both periods and a cost-effectiveness analysis was performed to study the efficiency.

RESULTS

In 2000, the number of visits increased by +12% (CI 95%: 2% to 22%). Despite this increase, we observed an improvement of most efficacy and health-care quality markers after the ED reforms. E1 increased by 996% (CI 95%: 335% to 1,658%) and E2 increased by 186% (CI 95%: -23%to 395%). Cost-effectiveness analysis showed 70% (CI 95%: 33%to 107%) and 56% (CI 95%: 18% to 94%) increases regarding E1 and E2, respectively, after the reforms.

CONCLUSIONS

Providing ED with the necessary resources leads to an objective improvement of its efficacy and health-care quality and, consequently, the service and quality perceived by users improve. Despite the total cost increase after the ED reforms, efficiency also improves.

[Relative effects of external and internal factors on emergency department efficiency]

BACKGROUND

To know the relative effect of external and internal factors on emergency department (ED) efficiency.

PATIENTS AND METHOD

Along 3 consecutive weeks we compute at 3 hours-interval the number or patient waiting for visit and the mean waiting time for visit (efficiency markers), the number of patients arriving to ED (external pressure marker) and the number of patients remaining in ED after beginning the visit (internal pressure marker), which was divided in ED-related factors, hospital-related factors, ED-hospital interelation-related factors, or not caused by ED nor hospital-related factors.

RESULTS

Only the increase of internal pressure was associated with a decline in ED efficiency (p < 0.001). ED-related and hospital-related factors were those significantly associated with such a decline (p < 0.05 and p < 0.01, respectively).

CONCLUSION

Internal pressure generated by the own ED exerts a prominent role in its dysfunction; therefore, policies addressed to reduce such internal pressure should be encouraged.

Particulate air pollution and asthma: a review of epidemiological and biological studies

The link between exposure to air pollution and exacerbation of asthma symptoms has been investigated by epidemiological study and by direct biological experimentation. In asthmatics, epidemiological studies generally show a positive correlation between the particulate fraction of air pollution and increased morbidity, although roles for other co-pollutants (for example, ozone) are implicated as well. Direct experimentation using air pollutants, especially particles, to investigate their effects on humans or on animal models of asthma provides corroboration of the epidemiology and has begun to identify the pathophysiological mechanisms involved. We begin this review with an overview of air pollution, followed by a survey of the epidemiological and experimental data regarding air pollution particles and asthma. We finish with a discussion of directions for future research.