Environmental risk factors (outdoor air pollution and climatic changes) and increased trend of respiratory allergy.

A wealth of evidence suggests that allergic respiratory diseases such as rhinosinusitis and bronchial asthma have become more common worldwide in recent years and a great deal of etiological and pathogenic research has been carried out to evaluate the possible causes of this increasing trend. There is also some evidence that increased atmospheric concentrations of pollutants such as ozone (O3), nitric oxides (NOx), respirable particulate (PM10) and volatile organic chemicals (VOC5), which result from increased use of liquid petroleum gas or kerosene, may be linked to the increased prevalence of allergic diseases which develop more frequently in urban areas of developed countries. Since bronchial asthma is a syndrome which can be aggravated by inhaled compounds, the effects of air pollutants on health have been the focus of attention. In fact, various studies have demonstrated that inhalation of air pollutants such as O3, nitrogen dioxide (NO2) and sulfur dioxide (SO2), either individually or in combination, can enhance the airway response to inhaled allergens in atopic subjects, thus inducing asthma exacerbations. Moreover, experimental studies have shown that diesel exhaust particulate causes respiratory symptoms and is able also to modulate the immune response by increasing IgE synthesis in predisposed animals and humans. There is also some evidence that air pollutants can interact with aeroallergens in the atmosphere and/or on human airways, potentiating their effects. In fact, by inducing airway inflammation which increases epithelial permeability, some pollutants overcome the mucosal barrier and lead to allergen-induced responses. However, air pollution and climatic changes should also have an indirect effect on allergic response by influencing quantitatively and qualitatively the pollen production by allergenic plants.     

Short-term effects of air pollution on daily asthma emergency room admissions.

Many time-series studies have shown positive associations between air pollutants and asthma morbidity. However, few studies have included pollen as a potential confounder when examining this relationship. This study analysed the short-term association between air pollutants (sulphur dioxide (SO2), particles measured with a median aerodynamic diameter of <10 microm (PM10), nitrogen dioxide (NO2) and ozone (O3)) and asthma emergency room admissions in Madrid, Spain, in 1995-1998, adjusting for four types of pollen with allergenic potential (Olea europaea, Plantago sp., Poaceae and Urticaceae). Data were analysed using autoregressive Poisson regression and generalised additive models (GAM). The strongest associations were observed at 1 day lag for O3, and 3 days lag for the remaining pollutants. Using Poisson regression, a single-pollutant model showed that a 10-microg x m(-3) rise in pollutant level led to relative risks of: 1.039 for PM10; 1.029 for SO2; 1.033 for NO2; and 1.045 for O3. Adjustment for the different types of pollen led to no substantial variation in these associations. In the multipollutant models for cold-season pollutants (including PM10, SO2 and the four types of pollen) and photochemical pollutants (including NO2, O3 and the four types of pollen) the associations for PM10, NO2 and O3 held, but no relationship with SO2 was evident. GAM analysis yielded the same results, both in terms of lags and of quantification of the effect for all pollutants. In conclusion, the usual air pollution levels in Madrid were associated with an increase in asthma emergency room admissions, and this association remained controlling for the presence of ambient pollen.     

Prospective study of air pollution and bronchitic symptoms in children with asthma

The relationship of bronchitic symptoms to ambient particulate matter and to particulate elemental and organic carbon (OC), nitrogen dioxide (NO2), and other gaseous pollutants was examined in a cohort of children with asthma in 12 Southern California communities. Symptoms, assessed yearly by questionnaire from 1996 to 1999, were associated with the yearly variability of particulate matter with aerodynamic diameter less than 2.5 microg (odds ratio [OR] 1.09/microg/m3; 95% confidence interval [CI] 1.01-1.17), OC (OR 1.41/microg/m3; 95% CI 1.12-1.78), NO2 (OR 1.07/ppb; 95% CI 1.02-1.13), and ozone (OR 1.06/ppb; 95% CI 1.00-1.12). The ORs associated with yearly within-community variability in air pollution were larger than the effect of the between-community 4-year average concentrations. In two pollutant models, the effects of yearly variation in OC and NO2 were only modestly reduced by adjusting for other pollutants, except in a model containing both OC and NO2; the effects of all other pollutants were reduced after adjusting for OC or NO2. We conclude that OC and NO2 deserve greater attention as potential causes of the chronic symptoms of bronchitis in children with asthma and that previous cross-sectional studies may have underestimated the risks associated with air pollution.     

Asthma and air quality

PURPOSE OF REVIEW: There is evidence for an association between asthma and air pollutants, including ozone, NO2 and particulate matter. Since these pollutants are ubiquitous in the urban atmosphere and typically correlated with each other it has been difficult to ascertain the specific sources of air pollution responsible for the observed effects. Similarly, uncertainty in determining a causal agent, or multiple agents, has complicated efforts to identify the mechanisms involved in pollution-mediated asthma events and whether air pollution may cause asthma as well as exacerbate preexisting cases. RECENT FINDINGS: Numerous studies have examined specific sources of air pollution and their relationship to asthma. This review summarizes recent work conducted, specifically, on traffic pollution and presents results that elucidate several plausible biological mechanisms for the observed effects. Of note are studies linking susceptibility to several genetic polymorphisms. Together, these studies suggest that remaining uncertainties in the asthma-air pollution association may be addressed through enhanced assessment of both exposures and outcomes. SUMMARY: Air-pollution research is evolving rapidly; in the near future, clinicians and public health agencies may be able to use this new information to provide recommendations for asthmatics that go beyond only paying attention to the air-pollution forecast.     

Increased asthma medication use in association with ambient fine and ultrafine particles.

The association between particulate air pollution and asthma medication use and symptoms was assessed in a panel study of 53 adult asthmatics in Erfurt, Germany in winter 1996/1997. Number concentrations of ultrafine particles, 0.01-0.1 microm in diameter (NC(0.01-0.1), mean 17,300 x cm(-3), and mass concentrations of fine particles 0.01-2.5 microm in diameter (MC(0.01-2.5)), mean 30.3 microg x m(-3), were measured concurrently. They were not highly correlated (r=0.45). The associations between ambient particle concentrations and the prevalence of inhaled beta2-agonist, corticosteroid use and asthma symptoms, were analysed separately with logistic regression models, adjusting for trend, temperature, weekend, holidays, and first order autocorrelation of the error. Cumulative exposures over 14 days of ultrafine and fine particles were associated with corticosteroid use. Beta2-agonist use was associated with 5-day mean NC(0.01-0.1) and MC(0.01-2.5). The prevalence of asthma symptoms was associated with ambient particle concentrations. The results suggest that reported asthma medication use and symptoms increase in association with particulate air pollution and gaseous pollutants such as nitrogen dioxide.     

Prevalence of symptoms of asthma, rhinitis, and atopic eczema in Brazilian adolescents related to exposure to gaseous air pollutants and socioeconomic status.

OBJECTIVES: To evaluate the relationship between exposure to gaseous air pollutants (ozone [O3], carbon monoxide [CO], nitrogen dioxide [NO2], and sulfur dioxide [SO2]) socioeconomic status and the prevalence of symptoms of asthma, rhinitis and atopic eczema in adolescents. SUBJECTS AND METHODS: A sample of 16 209 adolescents from S?o Paulo West (SPW), S?o Paulo South (SPS), Santo André (SA), Curitiba (CR), and Porto Alegre (PoA) were enrolled. Data on air pollutants and socioeconomic status were compared to prevalence of symptoms with the Spearman correlation coefficient. RESULTS: Socioeconomic status was quite similar in all cities. The levels of O3 in SPW, SPS, and SA, and of CO in SA were higher than the acceptable ones. In relation to O3 and CO exposures, adolescents from SPW and SA had a significant risk of current wheezing, whereas living in SPW was associated with a high risk of rhinoconjunctivitis, eczema, and flexural eczema and living in CR to rhinitis. Exposure to NO2 was associated with a high risk of current wheezing in SPW and SA, and of severe asthma in SPW and PoA. Exposure to SO2 was associated with a high risk of current wheezing in SPW and SA, severe asthma in SPW and PoA, and nighttime cough, eczema, flexural eczema and severe eczema in SPW. Living in SPW, CR, or PoA was associated with a high risk of rhinitis, rhinoconjunctivitis, and severe rhinitis. CONCLUSIONS: Although we did not detect a characteristic pattern for all symptoms evaluated or a specific air pollutant, our data suggest a relationship between higher exposure to photochemical pollutants and high prevalence or risk of symptoms of asthma, rhinitis, and atopic eczema.     

Air pollution and hospital admissions for respiratory conditions in Rome, Italy.

Most of the evidence regarding the association between particulate air pollution and emergency room visits or hospital admissions for respiratory conditions and asthma comes from the USA. European time-series analyses have suggested that gaseous air pollutants are important determinants of acute hospitalization for respiratory conditions, at least as important as particulate mass. The association between daily mean levels of suspended particles and gaseous pollutants (sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone) was examined. The daily emergency hospital admissions for respiratory conditions in the metropolitan area of Rome during 1995-1997 were also recorded. Daily counts of hospital admissions for total respiratory conditions (43 admissions day(-1)), acute respiratory infections including pneumonia (18 day(-1)), chronic obstructive pulmonary disease (COPD) (13 day(-1)), and asthma (4.5 day(-1)) among residents of all ages and among children (0-14 yrs) were analysed. The generalized additive models included spline smooth functions of the day of study, mean temperature, mean humidity, influenza epidemics, and indicator variables for day of the week and holidays. Total respiratory admissions were significantly associated with same-day level of NO2 (2.5% increase per interquartile range (IQR) change, 22.3 microg x m(-3)) and CO (2.8% increase per IQR, 1.5 mg x m(-3)). No effect was found for particulate matter and SO2, whereas O3 was associated with admissions only among children (lag 1, 5.5% increase per IQR, 23.9 microg x m3). The effect of NO2 was stronger on acute respiratory infections (lag 0, 4.0% increase) and on asthma among children (lag 1, 10.7% increase). The admissions for all ages for asthma and COPD were associated only with same-day level of CO (5.5% and 4.3% increase, respectively). Multipollutant models confirmed the role of CO on all respiratory admissions, including asthma and COPD, and that of NO2 on acute respiratory infections. Among children, O3 remained a strong indicator of acute respiratory infections. Carbon monoxide and photochemical pollutants (nitrogen dioxide, ozone) appear to be determinants of acute respiratory conditions in Rome. Since carbon monoxide and nitrogen dioxide are good indicators of combustion products from traffic related sources, the detected effect may be due to unmeasured fine and ultrafine particles.     

Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan.

The prevalence of allergic rhinitis, a common respiratory disorder, may be rapidly increasing. Epidemiological studies, however, indicate little about its association with climatic factors and air pollution. The relationship between traffic-related air pollutants and allergic rhinitis in middle-school students was therefore investigated. In a nationwide survey of middle-school students in Taiwan conducted in 1995/1996, the lifetime prevalence of physician-diagnosed allergic rhinitis and typical symptoms of allergic rhinitis were compared with air-monitoring station data on temperature, relative humidity, sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO) and particulate matter with a 50% cut-off aerodynamic diameter of 10 microm (PM10). A total of 331,686 nonsmoking children attended schools located within 2 km of 55 stations. Mean (range) annual exposures were: CO 853 (381-1,610) parts per billion (ppb), NOx 35.1 (10.2-72.4) ppb, SO2 7.57 (0.88-21.2) ppb, PM10 69.2 (40.1-116.2) microg x m(-3), O3 21.3 (12.4-34.1) ppb, temperature 22.9 (19.6-25.1) degrees C, and relative humidity 76.2 (64.8-86.2)%. The prevalence of physician-diagnosed allergic rhinitis was 28.6 and 19.5% in males and females, respectively, with prevalence of questionnaire-determined allergic rhinitis 42.4 and 34.0%. After adjustment for age, parental education and history of atopic eczema, physician-diagnosed allergic rhinitis was found to be associated with higher nonsummer (September-May) warmth and traffic-related air pollutants, including CO, NOx and O3. Questionnaire-determined allergic rhinitis correlated only with traffic-related air pollutants. Nonsummer warmth and traffic-related air pollution, probably mediated through exposure to common allergens such as dust mites, are possible risk factors for allergic rhinitis in middle-school-aged children.     

Effects of inhalable particles on respiratory health of children

Results are presented from a second cross-sectional assessment of the association of air pollution with chronic respiratory health of children participating in the Six Cities Study of Air Pollution and Health. Air pollution measurements collected at quality-controlled monitoring stations included total suspended particulates (TSP), particulate matter less than 15 microns (PM15) and 2.5 microns (PM2.5) aerodynamic diameter, fine fraction aerosol sulfate (FSO4), SO2, O3, and No2. Reported rates of chronic cough, bronchitis, and chest illness during the 1980-1981 school year were positively associated with all measures of particulate pollution (TSP, PM15, PM2.5, and FSO4) and positively but less strongly associated with concentrations of two of the gases (SO2 and NO2). Frequency of earache also tended to be associated with particulate concentrations, but no associations were found with asthma, persistent wheeze, hay fever, or nonrespiratory illness. No associations were found between pollutant concentrations and any of the pulmonary function measures considered (FVC, FEV1, FEV0.75, and MMEF). Children with a history of wheeze or asthma had a much higher prevalence of respiratory symptoms, and there was some evidence that the association between air pollutant concentrations and symptom rates was stronger among children with these markers for hyperreactive airways. These data provide further evidence that rates of respiratory illnesses and symptoms are elevated among children living in cities with high particulate pollution. They also suggest that children with hyperreactive airways may be particularly susceptible to other respiratory symptoms when exposed to these pollutants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of asthma and mean levels of air pollution: results from the French PAARC survey. Pollution Atomosphérique et Affections Respiratoires Chroniques.

Among the possible explanations for the recent increase in the prevalence of asthma in several countries, air pollution is one of the foremost public health concerns. Data from the "Pollution Atmosphérique et Affections Respiratoires Chroniques" (PAARC) survey collected in 24 areas of seven French towns during 1974-1976 were reanalysed to assess the relationship between the prevalence of asthma and the following air pollutants: sulphur dioxide (specific (SO2) and acidimetric methods), total suspended particles (TSP), black smoke (BS), nitrogen dioxide and nitric oxide. Correlation coefficients between annual mean levels of pollution and prevalence of asthma in the different areas were first calculated. Random-effects models were then estimated. Of the 20,310 adults aged 25-59 yrs, 1,291 (6.4%) were found to be asthmatics as well as 195 (6.1%) of the 3,193 children aged 5-9 yrs. A geographical correlation between asthma and annual mean level of SO2 (ranging 17-85 microg x m(-3)) was found (r=0.45, p=0.01) in adults. No relationship was found in children. After controlling for age, educational level, smoking, and geographical clustering with a multivariate random-effects model, the relationship remained significant in adults for SO2 (odds ratio for a 50 microg x m(-3) increase=1.24, confidence interval 1.08-1.44, p=0.0035). It also remained significant when taking into account only the people reporting their last asthma attack occurring after settling in the study area. These results are consistent with the known short-term effects of SO2 in asthma and demonstrate the necessity for further studies on delayed effects of air pollution in respiratory diseases.     

Effects of atmospheric sulphur dioxide and particulate matter concentrations on emergency room admissions due to asthma in Ankara

Recent studies have associated short-term exposure to respirable particulate matter (PM(10)) and sulphur dioxide (SO(2)) with peak flow decrements, increased symptoms of respiratory irritation, increased use of asthma medications, and increased admission and hospitalization for asthma. To further delineate the association between SO(2), PM(10) exposure and asthmatic response, we compiled daily records of asthma emergency room visits from our hospital and data of meteorological conditions, SO(2) and PM(10) concentrations in Ankara area. Weekly averages of daily counts of emergency room visits for asthma were significantly associated with average weekly SO(2) and PM(10) exposure on previous week (r= 0.328, p= 0.017 and r= 0.355, p= 0.009 respectively). Admission to emergency room for asthma count was also negatively correlated with ambient temperature (r= -0.496, p= 0.0001) and strong wind existence (X(2)= 3.930, p= 0.047) on previous days. It was also positively correlated with ambient relative humidity (r= 0.531, p= 0.0001). We observed that numbers of emergency visits due to asthma were higher in winter months, April and September. In winter and early spring period there was concordance between asthma emergency admissions with air pollutants levels. During this period ambient temperatures were low as well. There were two discordance points in monthly variation of air pollution and asthma visits. We thought that first asthma visits peak was related to allergic pollens during April and second peak was due to opening of schools and increasing of respiratory infections for this reason during September. The general pattern of our results confirms that even low levels of air pollution encountered in Ankara are linked to short-term increases in the number of people visiting emergency department for asthma.     

Association between nitrogen dioxide and heart rate variability in a susceptible population.

BACKGROUND: Panel studies have shown a consistent association between changes in the cardiac autonomic nervous system with particulate matters (PM) but less with gaseous pollutants. This study examined the linkage between nitrogen dioxide (NO2) and heart rate variability (HRV) in a susceptible population. METHODS: We recruited a panel of 83 patients from the National Taiwan University Hospital Cardiology Clinic to measure their 24-h HRV by ambulatory electrocardiography. Thirty-nine patients had coronary heart disease (CHD) and another 44 patients had more than one major CHD risk factor. Ambient concentrations of NO2, sulphur dioxide (SO2), carbon monoxide (CO), ozone, and PM less than 10 microm in diameter (PM10) at each participant's close-by monitoring station were used to represent study participants' exposures. We used linear mixed-effects models to analyse the association between individual air pollutants and log10-transformed HRV, with key personal and environmental attributes and co-pollutants being adjusted. RESULTS: We found that an increase in 10 ppb NO2 at 4-h to 8-h moving averages was associated with 1.5-2.4% decreases in the standard deviation of all normal-to-normal intervals (SDNN) in our participants. For every 10 ppb NO2 at 5 and 7-h moving averages, our participants' low frequency was decreased by 2.2 and 2.5%, respectively. In contrast, HRV was not associated with PM10, CO, SO2, or O3. CONCLUSION: Increasing NO2 exposure was found to be associated with decreasing SDNN and low frequency in susceptible populations.     

Outdoor air pollution: nitrogen dioxide, sulfur dioxide, and carbon monoxide health effects

Nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide are important ambient air pollutants. High-intensity, confined space exposure to NO2 has caused catastrophic injury to humans, including death. Ambient NO2 exposure may increase the risk of respiratory tract infections through the pollutant's interaction with the immune system. Sulfur dioxide (SO2) contributes to respiratory symptoms in both healthy patients and those with underlying pulmonary disease. Controlled human exposure studies have demonstrated that experimental SO2 exposure causes changes in airway physiology, including increased airways resistance. Both acute and chronic exposure to carbon monoxide are associated with increased risk for adverse cardiopulmonary events, including death. However, studies have not demonstrated a clear dose-dependent health risk response to increasing amounts of these pollutants except at high concentrations. In addition, a number of studies examining the effects of ambient level exposure to NO2, SO2, and CO have failed to find associations with adverse health outcomes.     

Air pollution and child respiratory health: a case-crossover study in Australia and New Zealand

RATIONALE: The strength of the association between outdoor air pollution and hospital admissions in children has not yet been well defined. OBJECTIVES: To estimate the impact of outdoor air pollution on respiratory morbidity in children after controlling for the confounding effects of weather, season, and other pollutants. METHODS: The study used data on respiratory hospital admissions in children (three age groups: < 1, 1-4, and 5-14 years) for five cities in Australia and two in New Zealand. Time series of daily numbers of hospital admissions were analyzed using the case-crossover method; the results from cities were combined using a random-effects meta-analysis. MEASUREMENTS AND MAIN RESULTS: Significant increases across the cities were observed for hospital admissions in children for pneumonia and acute bronchitis (0, 1-4 years), respiratory disease (0, 1-4, 5-14 years), and asthma (5-14 years). These increases were found for particulate matter with a diameter less than 2.5 microm (PM2.5) and less than 10 microm (PM10), nephelometry, NO2, and SO2. The largest association found was a 6.0% increase in asthma admissions (5-14 years) in relation to a 5.1-ppb increase in 24-hour NO2. CONCLUSIONS: This study found strong and consistent associations between outdoor air pollution and short-term increases in childhood hospital admissions. A number of different pollutants showed significant associations, and these were distinct from any temperature (warm or cool) effects.     

Sulfur dioxide-induced bronchoconstriction in freely breathing, exercising, asthmatic subjects

The purpose of this study was to determine whether 0.50 ppm sulfur dioxide (SO2) in filtered air causes bronchoconstriction in freely breathing asthmatic subjects exercising at a moderately heavy work rate. Ten volunteers who had mild asthma breathed air containing no SO2 or containing 0.50 ppm SO2 In an exposure chamber as they exercised for 5 min on a cycle ergometer at a work rate of 750 kilopond meters/min (about 125 watts). We determined their specific airway resistance by body plethysmography before and after exercise. Specific airway resistance increased by 13.55 +/- 9.18 cm H2O X s (mean +/- SD) when subjects exercised and breathed 0.50 ppm SO2 but only by 2.24 +/- 2.34 when they exercised and breathed air without SO2 (p less than 0.005). Thus, 0.50 ppm SO2 causes significant bronchoconstriction in freely breathing asthmatics during moderately heavy exercise.     

Health effects of daily indoor nitrogen dioxide exposure in people with asthma.

Household gas appliances produce nitrogen dioxide (NO2), which may be associated with an increase in symptoms in asthmatics. The relationship between indoor NO2 exposure, and respiratory symptoms in people with asthma was evaluated. Self-reported asthmatics (n=125) wore lapel badges that measured NO2 daily over 6 weeks at home. Outdoor pollutants, spores and meteorological parameters were measured daily, in addition to smoking status and demographic factors. Seven asthma symptoms were recorded in diaries, for analysis by same day and also with 1 day lag exposures, using a generalized estimating equation. Significant interactions were demonstrated between NO2 at age < or =14 yrs, with respect to the symptoms of chest tightness on the same day (odds ratio (OR): 1.29, 95% confidence interval (CI): 1.16-1.43) and with a 1 day lag (OR: 1.29, 95% CI: 1.14-1.46), breathlessness on exertion with a 1 day lag (OR: 1.13, 95% CI: 1.00-1.28), daytime asthma attacks on the same day (OR: 1.13, 95% CI: 1.02-1.26) night asthma attacks on the same day (OR: 1.16, 95% CI:1.03-1.30) and with a 1 day lag (OR: 1.15, 95% CI; 1.03-1.29) after adjustment for potential confounders. A significant interaction between NO2 and age 35-49 yrs was demonstrated for coughs with a 1 day lag (OR: 1.15, 95% CI: 1.01-1.31). Daily personal exposures to NO2 are associated with asthmatic symptoms in children.     

Long-term exposure to ambient air pollution and respiratory disease mortality in shenyang, china: a 12-year population-based retrospective cohort study

Background: In China, both the levels and patterns of outdoor air pollution have altered dramatically with the rapid economic development and urbanization over the past two decades. However, few studies have investigated the association of outdoor air pollution with respiratory mortality, especially in the high pollution range. Objective: We conducted a retrospective cohort study of 9,941 residents aged ≥35 years old in Shenyang, China, to examine the association between outdoor air pollutants [particulate matter <10 μm in aerodynamic diameter (PM(10)), sulfur dioxide (SO(2)) and nitrogen dioxide (NO(2))] and mortality using 12 years of data. Methods: We applied extended Cox proportional hazards modeling with time-dependent covariates to respiratory mortality. Analyses were also stratified by age, sex, educational level, smoking status, personal income, occupational exposure and body mass index (BMI) to examine the association of air pollution with mortality. Results: We found significant associations between PM(10) and NO(2) levels and respiratory disease mortality. Our analysis found a relative risk of 1.67 [95% confidence interval (CI) 1.60-1.74] and 2.97 (95% CI 2.69-3.27) for respiratory mortality per 10 μg/m(3) increase in PM(10) and NO(2), respectively. The effects of air pollution were more apparent in women than in men. Age, sex, educational level, smoking status, personal income, occupational exposure, BMI and exercise frequency influenced the relationship between outdoor PM(10) and NO(2) and mortality. For SO(2), only smoking, little regular exercise and BMI above 18.5 influenced the relationship with mortality. Conclusion: These data contribute to the scientific literature on the long-term effects of air pollution for the high-exposure settings typical in developing countries.     

空气污染对哮喘患者健康的负面影响

空气污染与哮喘发生和加重相关,其机制包括过氧化和损伤,气道重塑,炎性通路和异常免疫反应,以及呼吸系统对过敏原敏感性的增强等。哮喘患者暴露于臭氧、NO2和SO2等空气污染物可发生气道急性效应。预防空气污染所致哮喘的方法包括食用维生素C饮食、补充维生素D、肥胖哮喘患者积极减肥,减少二手烟污染,以及控制空气中细颗粒物浓度。     

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.     

Urban air pollution and emergency admissions for cerebrovascular diseases in Taipei, Taiwan.

AIMS: This study was designed to evaluate the association between urban air pollutants and emergency admissions for cerebrovascular diseases. METHODS AND RESULTS: Daily emergency admissions for cerebrovascular diseases (ICD-9-CM, 430-437) to the National Taiwan University Hospital were regressed against daily concentrations of carbon monoxide (CO), nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)), ozone (O(3)), and particulate matters with aerodynamic diameter <2.5 (PM(2.5)) and 10 microm (PM(10)) from 12 April 1997 to 31 December 2002 in Taipei metropolitan areas by the Poisson regression models adjusting for meteorological conditions and temporal trends. Single-pollutant models showed O(3) lagged 0 day, CO lagged 2 days, and PM(2.5) and PM(10) lagged 3 days were significantly associated with increasing emergency admissions for cerebrovascular diseases and CO lagged 2 days was significantly associated with increasing emergency admissions for strokes (ICD-9-CM, 430-434). Such association remained significant for O(3), CO, and cerebrovascular admissions after adjusting for PM(2.5) and PM(10) in two-pollutant models. The odds ratios were 1.021-1.022 per 31.3 ppb O(3) and 1.023-1.031 per 0.8 ppm CO, respectively. However, only CO was significantly associated with emergency admissions for stroke in the three-pollutant models with CO, O(3), and PM(2.5) or PM(10). CONCLUSION: Emergency admissions for cerebrovascular diseases among adults were positively associated with increasing urban air pollution levels of O(3) lagged 0 day and CO lagged 2 days in Taipei.