Air pollution and asthma.

The role of air pollution in the increased prevalence and morbidity of asthma has been widely debated, but results to date indicate that the normally encountered levels of air pollution are unlikely to contribute to a worsening of asthma. When the levels of sulphur dioxide (SO2) are exceptionally high it is possible that asthmatic patients may have increased symptoms after exertion, since this irritant gas acts as a trigger to bronchoconstriction. There is also evidence that suspended particles may also act as an inciter of asthma symptoms when concentrations are high. Experimentally, ozone in high concentrations may increase airway responsiveness in both normal and asthmatic subjects by inducing airway inflammation, but asthmatic individuals show the same responses as normal subjects and there is little or no evidence to link increases in ambient ozone with an increase in asthma. There is little evidence that nitrogen dioxide (NO2), even at the peak levels recorded, has any significant effect on airway function in normal or asthmatic individuals. Other air pollutants which are present in lower concentrations have not been studied as extensively, but there is no convincing evidence that they cause significant respiratory symptoms in asthmatic patients. It is still possible that combinations of air pollutants may have greater effects on airway function than exposure to a single pollutant, although there is little evidence to support this. Epidemiological evidence provides little support for the idea that atmospheric pollution levels are related to the frequency of asthma symptoms or the frequency of attacks. More importantly, there is no evidence that asthma prevalence or aetiology is related to the level of air pollution. A review of currently available information therefore provides little evidence for the widely expressed view that atmospheric pollution is related to increased prevalence or morbidity of asthma or is related to the causation of asthma.     

大气污染与呼吸道微生态

大气污染是由存在于大气中的一种或多种气态、气溶胶或颗粒状态的污染物引起的，可对人和其他生物造成伤害或反常的作用。在地区性的大气污染中，影响较大的是粉尘、SO2，NOx，CO，总氧化剂（O3），CxHm和重金属等。大气污染来源广泛、影响范围大，目前已成为世界性问题。     

大气污染物对人体健康影响的研究

近年来我国大气污染问题日益严重,国内外的大量研究表明:大气污染与许多健康效应直接或间接相关,可对人体呼吸、循环、免疫、神经等多个系统产生不良影响,造成肺功能下降、心血管疾病发生率和死亡率升高.该文综述了大气污染物主要组成成分,综合大气污染物与人群健康效应的流行病学及毒理学资料,以获取主要大气污染物健康效应的可能机制,并总结大气污染物的研究方向,为今后开展此类研究提出建议.     

Air pollution and its health impacts: the changing panorama

Urban air pollution levels are associated with increased mortality and cardiorespiratory morbidity. These health effects occur even at exposure levels below those stipulated in current air-quality guidelines, and it is unclear whether a safe threshold exists. Air pollution in Australia and New Zealand comes primarily from motor vehicle emissions, electricity generation from fossil fuels, heavy industry, and home heating using wood and coal. In individual patients a direct link between symptoms and air pollution exposure may be difficult to establish and may not change their clinical management. However, avoiding exposure during periods of peak pollution may be beneficial. Although there is some evidence that urban air pollution in Australia and New Zealand has been decreasing (through reduced car use, improved emission-control technology and use of more energy-efficient devices in the household and in industry), pollution levels are still unsatisfactory. Further reductions may prevent hundreds of cardiorespiratory hospital admissions and deaths each year.