空气污染与儿童哮喘

工业化导致的空气污染是儿童哮喘发生、发展的高危因素之一。常见的空气污染物种类繁多,如交通相关空气污染物、多环芳香烃、香烟烟雾、尘埃颗粒及细颗粒物 PM 2.5等,均与儿童哮喘密切相关。它们通过各种相关信号通路,从而调节哮喘进程;同时空气污染导致的哮喘相关基因表观遗传学改变、上皮间充质转化及遗传多态性等亦影响儿童哮喘个体异质性及诊疗个体化。目前,空气污染与儿童哮喘研究已取得一定进展,但其确切机制仍需进一步研究。本文就常见的空气污染物参与儿童哮喘的发生、发展及其机制进行阐述。     

Air pollution and development of asthma, allergy and infections in a birth cohort.

Few studies have addressed associations between traffic-related air pollution and respiratory disease in young children. The present authors assessed the development of asthmatic/allergic symptoms and respiratory infections during the first 4 yrs of life in a birth cohort study (n = approximately 4,000). Outdoor concentrations of traffic-related air pollutants (nitrogen dioxide PM(2.5), particles with a 50% cut-off aerodynamic diameter of 2.5 mum and soot) were assigned to birthplace home addresses with a land-use regression model. They were linked by logistic regression to questionnaire data on doctor-diagnosed asthma, bronchitis, influenza and eczema and to self-reported wheeze, dry night-time cough, ear/nose/throat infections and skin rash. Total and specific immunoglobulin (Ig)E to common allergens were measured in a subgroup (n = 713). Adjusted odds ratios (95% confidence intervals) per interquartile pollution range were elevated for wheeze (1.2 (1.0-1.4) for soot), doctor-diagnosed asthma (1.3 (1.0-1.7)), ear/nose/throat infections (1.2 (1.0-1.3)) and flu/serious colds (1.2 (1.0-1.4)). No consistent associations were observed for other end-points. Positive associations between air pollution and specific sensitisation to common food allergens (1.6 (1.2-2.2) for soot), but not total IgE, were found in the subgroup with IgE measurements. Traffic-related pollution was associated with respiratory infections and some measures of asthma and allergy during the first 4 yrs of life.     

Air pollution

Despite progress in improving ambient air quality and reducing personal exposures to air pollutants in indoor settings, population exposures to air pollutants remain widespread and are an important public health concern. Many air pollutants are associated with adverse health effects; the most serious include development and exacerbation of asthma, loss of lung function, impaired neurobehavioral development, and death. These outcomes are the focus of current health effects research on environmental tobacco smoke and radon in indoor settings, and lead, ozone, and particulate matter outdoors. Advances in methods to measure exposures to specific pollutants and the identification of markers of individual susceptibility are providing improved data on the relation of exposure and disease, and, in turn, will improve efforts to protect public health.     

Air pollution, bronchial asthma, and acute respiratory infections in minors, Habana City

OBJECTIVE: To identify the relationship between emergency visits for acute respiratory illnesses, acute bronchial asthma crisis (ABAC) and acute respiratory infections (ARI), in children less than 14 years of age, and the daily changes of air pollutant levels, in two central hospitals of Havana City, between October 1st 1996 and March 16 1998. MATERIAL AND METHODS: An ecological time series study was conducted. We assessed the relationship between the presence of acute respiratory illnesses, ABAC, and IRA, and exposure to levels of particles less than 10 microg/m3 (PM10), smoke, and sulfur dioxide (SO2); negative binomial regression models were used to assess latency periods of one to five days as well as the cumulative effect of seven days before the emergency visit. RESULTS: The levels of atmospheric pollutants were low, in general. The 24-hour mean values for PM10 levels, smoke, and SO2, were 59.2 microg/m3 (SD=29.2), 27.7 microg/m3 (SD=21.2), and 21.1 microg/m3 (SD=20.1), respectively. An increase of 20 microg/m3 in the daily average of black smoke was associated with a 2.2% increase (95% CI 0.9-3.6) in the number of emergency visits for ABAC. A 20 microg/m3 increase in the daily average of black smoke and SO was associated with an increase in ARI of 2.4% (95% CI 1.2-3.6), and 5% (95% CI 1.3-5.3), respectively, with a 5-day lag. We also observed a cumulative effect for all the contaminants studied. CONCLUSIONS: These results suggest that air pollution levels in Havana City affect children's respiratory health; therefore implementation of control measures is necessary, especially those aimed at decreasing motor vehicle exhaust fumes. The English version of this paper is available at: http://www.insp.mx/salud/index.html.     

Air pollution and health

The health effects of air pollution have been subject to intense study in recent years. Exposure to pollutants such as airborne particulate matter and ozone has been associated with increases in mortality and hospital admissions due to respiratory and cardiovascular disease. These effects have been found in short-term studies, which relate day-to-day variations in air pollution and health, and long-term studies, which have followed cohorts of exposed individuals over time. Effects have been seen at very low levels of exposure, and it is unclear whether a threshold concentration exists for particulate matter and ozone below which no effects on health are likely. In this review, we discuss the evidence for adverse effects on health of selected air pollutants.     

Air pollution and atopy

Relationships between air pollutants and atopy can be studied within 3 different settings. In vitro, exposure of pollen to air pollutants induce morphological changes and seems to facilitate extrusion on allergenic material out of the pollen grain. In animal as well as in human experiments, air pollutants, especially diesel exhaust particulates, are able to trigger an IgE-response. Epidemiological surveys also show that air pollutants trigger symptoms in patients. In contrast, whether or not air pollutants can induce de novo allergic diseases is still a matter of debate. Some surveys suggest that, in humans also, air pollutants, especially diesel-exhaust particulates, could trigger allergic sensitization and development of atopic diseases. At home, other pollutants can be involved: volatile organic compounds have pro-inflammatory properties and favour T-cell sensitization. Relationship between exposure to secondhand tobacco smoke or occupational hazards and atopic sensitization have led to discordant results.     

室外大气污染与支气管哮喘

近 2 0年来 ,欧、美、日本及其它诸多国家和地区均报道支气管哮喘 (简称哮喘 )发病率逐年上升且程度加重 ,而在工业城市这种趋势更为明显。其原因是多方面的 ,很多报道认为 ,室外大气中非抗原物质 ,主要包括ＳＯ2 、ＮＯ2 、Ｏ3 、悬浮颗粒物质 (ＰＭ)及金属离子 (Ｃｕ、Ｎｉ、Ｐｂ)等的污染是其中一个重要原因。这些物质可引起人体肺功能、气道反应性、免疫系统的变化 ,增强哮喘患者对抗原的敏感性 ,增加哮喘发病率并使症状加重[1 10 ] 。但也有研究认为 ,这些物质对哮喘无明显影响[1] 。为进一步了解非抗原污染物对哮喘的影响 ,近年来许多…     

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.     

Air pollution and COPD in China

Recently, many researchers paid more attentions to the association between air pollution and chronic obstructive pulmonary disease (COPD). Haze, a severe form of outdoor air pollution, affected most parts of northern and eastern China in the past winter. In China, studies have been performed to evaluate the impact of outdoor air pollution and biomass smoke exposure on COPD; and most studies have focused on the role of air pollution in acutely triggering symptoms and exacerbations. Few studies have examined the role of air pollution in inducing pathophysiological changes that characterise COPD. Evidence showed that outdoor air pollution affects lung function in both children and adults and triggers exacerbations of COPD symptoms. Hence outdoor air pollution may be considered a risk factor for COPD mortality. However, evidence to date has been suggestive (not conclusive) that chronic exposure to outdoor air pollution increases the prevalence and incidence of COPD. Cross-sectional studies showed biomass smoke exposure is a risk factor for COPD. A long-term retrospective study and a long-term prospective cohort study showed that biomass smoke exposure reductions were associated with a reduced decline in forced expiratory volume in 1 second (FEV₁) and with a decreased risk of COPD. To fully understand the effect of air pollution on COPD, we recommend future studies with longer follow-up periods, more standardized definitions of COPD and more refined and source-specific exposure assessments.     

Urban air pollution and asthma in children

This study investigated the relationship between atmospheric pollution and emergency hospital admission for asthma among children resident in Turin in the period 1997-1999, using a case-control design. On the basis of the primary diagnosis, pediatric patients (< 15 years old) resident in Turin and admitted for asthma were defined as cases (n(1) = 1,060); age-matched patients admitted for causes other than respiratory diseases or heart diseases were defined as controls (n(2) = 25,523). Nitrogen dioxide (NO(2) in microg/m(3)) and total suspended particulates (TSP in microg/m(3)) were considered as indicators of urban air pollution; sex and age of patient, seasonality, temperature, humidity, solar radiation, and day of admission were considered as principal confounders. Statistical analyses were performed using simple and multiple logistic regression models; the association between emergency admission for asthma and exposure was shown as percentage of risk modification for a 10 microg/m(3) increment of exposure to each pollutant and relative 95% confidence interval. The number of emergency admissions for respiratory causes rose significantly with increased exposure to each pollutant: 2.8% (95% CI, 0.7-4.9%) and 1.8% (95% CI, 0.3-3.2) for a 10 microg/m(3) increment of exposure to NO(2) and TSP, respectively. A significant association was found between increased number of hospital emergency admissions for respiratory causes and exposure to principal urban pollutants in Turin. The study confirms the results reported for other Italian and European cities, using a case-control design.