Article

Effects of personal particulate matter on peak expiratory flow rate of asthmatic children

Feng Chia University, 臺中市, Taiwan, Taiwan
Science of The Total Environment (Impact Factor: 4.1). 09/2007; 382(1):43-51. DOI: 10.1016/j.scitotenv.2007.04.016
Source: PubMed

ABSTRACT Many researches have shown that the particulate matter (PM) of air pollution could affect the pulmonary functions, especially for susceptible groups such as asthmatic children, where PM might decrease the lung function to different extents. To assess the effects of PM on health, most studies use data from ambient air monitoring sites to represent personal exposure levels. However, the data gathered from these fixed sites might introduce certain statistical uncertainties. The objectives of this study are to evaluate the effects of various size ranges of PM on peak expiratory flow rate (PEFR) of asthmatic children, and to compare the model performance of using different PM measurements (personal exposures versus fixed-site monitoring) in evaluation. Thirty asthmatic children, aged 6 to 12 years, who live near the fixed monitoring site in Sin-Chung City, Taipei County, Taiwan, were recruited for the study. Personal exposures to PM(1), PM(2.5), and PM(10) were measured continuously using a portable particle monitor (GRIMM Mode 1.108, Germany). In addition, an activity diary and questionnaires were used to investigate possible confounding factors in their home environments. The peak expiratory flow rate of each participant was monitored daily in the morning and in the evening for two weeks. Results showed several trends, although not necessarily statistically significant, between personal PM exposures and PEFR measurements in asthmatic children. In general, notable findings tend to implicate that not only fine particles (PM(2.5)) but also coarse particles (PM(2.5-10)) are likely to contribute to the exacerbation of asthmatic conditions. Stronger lagged effect and cumulative effect of PM on the decrements in morning PEFR were also found in the study. Finally, results of linear mixed-effect model analysis suggested that personal PM data was more suitable for the assessment of change in children's PEFR than ambient monitoring data.

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    • "A limited ability to assess lagged effects over several days could be one explanation for the missing association as most other studies report lagged effects. However, a study from Taiwan in asthmatic children also found no significant associations for the PEF rate and different measures of air pollutants from personal measurements or a fixed monitoring site (Tang et al., 2007). Most studies on UFP particles and respiratory diseases are panel studies, and only one study on hospital admission for respiratory diseases has been carried out so far (Andersen et al., 2008). "
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    ABSTRACT: Summing up, there are still open questions in the field of health effects of air pollution. One issue is the lack of knowledge regarding health effects of UFP. Furthermore, studies need to disentangle the impact of single pollutants in the complex pollutant mixture that ambient air pollution consists of. The scientific methods also need further development, especially regarding the estimation of individual exposure to ambient air pollution. With the aim of advancing beyond the current knowledge in the field of air pollution health effects, Mauderly et al. (2010) mention some key issues in research that should be addressed. In brief, they argue for mobile monitoring programs to improve understanding of temporal and spatial variation of pollutants, conducting time-activity surveys and exposure studies to gain insight into the contributions of indoor and outdoor pollutants to the personal exposure of an individual, or for certain subpopulations. Moreover, they recommend an extended number of air pollutants to be measured as well as the development of biomarkers for criteria pollutants, to facilitate reconstructing exposure-dose-response relationships. In addition to better assess exposure, the knowledge of health impacts needs to be advanced. The collection of data on an individual level should be intensified, despite being more expensive, to get a better idea of the length of exposure or certain windows of susceptibility e.g., during childhood or pregnancy. Furthermore, more effort needs to be put into the research of exposure-response functions and biological mechanisms (Mauderly et al., 2010). Although quite a number of modes of action have been suggested (see section 7), these were partly substantiated by toxicological and epidemiological studies unresolved issues remain. In addition, the knowledge how long it takes for a certain exposure to cause measurable health effects and also the subgroups of the population that are most susceptible needs to be extended.
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    • "Numerous epidemiologic studies have demonstrated associations between ambient air pollution and health outcomes, including mortality (Chen et al. 2008; Dales et al. 2004; Qian et al. 2007), hospitalizations (Dominici et al. 2006; Lin et al. 2004; Villeneuve et al. 2007; Wellenius et al. 2005), and lung function (Delfino et al. 2008; Jalaludin et al. 2000; Tang et al. 2007). Infant mortality is still a major contributor to childhood mortality (Glinianaia et al. 2004a). "
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    • "This method is therefore the most suitable for studies on large populations, although inevitably affected by a series of assumptions, sometimes critical, compared to the real exposure scenario. In general, exposure assessment is based on multiple regression models using fixed monitoring station measures combined with information on activities, exposure to tobacco smoke and infiltration efficiency of particles (Chang et al. 2003; Koenig et al. 2005; Tang et al. 2007; Wu et al. 2005). Such models are characterized by a limited or moderate predictive power. "
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