Air pollution is a serious public health concern globally [1]. Exposure to ambient air pollution increases mortality and morbidity [2]. Ambient air particulate matter (PM) is the main component of air pollution and has a significant impact on human health [3]. Epidemiologic studies have shown that lung function of people is adversely affected by exposure to airborne particulate matters (APM) pollution [4-6]. In the other words, there is evidence from past studies that ambient air PM (such as PM2.5 and PM1) is associated with decrement of lung function indices (such as FVC and FEV1) [7, 8]. Previous studies showed that fine PM such as PM2.5 and PM1 can reach the alveoli and penetrate deep into the airways and induce alveolar inflammation [9].
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Airborne particulate matters such as PM with an aerodynamic diameter ≤ 10, ≤ 2.5 and ≤ 1 μm (coarse, fine, and ultrafine PM), are considered as a proxy for the complex mixture of air pollutants which emitted by various sources. The coarse fraction of PM10 mostly originating from soil and natural sources [10]. Airborne PM with size less than 2.5 micrometers in diameter (fine and ultrafine PM) produced by mechanical and physical processes and mainly originating from combustion or being secondary aerosols from sources [5, 10]. Man-made airborne PM can be disseminated from traffic and industrials but natural airborne PM usually originated from natural sources such as dust storm which has become a basic challenge in Iran (is located in southwest Asia) in recent years [1]. Although some previous epidemiologic studies propose the hypothesis that PM from combustion sources are associated with higher health risks than natural sources, but natural components of PM during the Asian dust storm (ADS) period may cause difficult health problems …show more content…
In the present study, dust storm was defined according to the classification presented by Hoffmann et al [18]. In this classification, dust storms were classified in four categories (DS1–DS4, see Table 1) using the concentration of particulate matter with 10 micrometers or less in aerodynamic diameter (PM10) [18]. We defined dust storm (DS) event day when PM10 concentration was 200 µg m-3 or more during the study period. The other days were defined as non-DS event days. According to WHO air quality guidelines (AQGs) for 24-hour concentration of PM10 and to accurately distinguish the effect of airborne particles on human health, we considered non-dust days with daily PM10-concentration lower than 50 μg m−3 [19]. We extended the duration of our study to more than one season to increase the variability in ambient particulates concentration which tend to show seasonal
Airborne particulate matters such as PM with an aerodynamic diameter ≤ 10, ≤ 2.5 and ≤ 1 μm (coarse, fine, and ultrafine PM), are considered as a proxy for the complex mixture of air pollutants which emitted by various sources. The coarse fraction of PM10 mostly originating from soil and natural sources [10]. Airborne PM with size less than 2.5 micrometers in diameter (fine and ultrafine PM) produced by mechanical and physical processes and mainly originating from combustion or being secondary aerosols from sources [5, 10]. Man-made airborne PM can be disseminated from traffic and industrials but natural airborne PM usually originated from natural sources such as dust storm which has become a basic challenge in Iran (is located in southwest Asia) in recent years [1]. Although some previous epidemiologic studies propose the hypothesis that PM from combustion sources are associated with higher health risks than natural sources, but natural components of PM during the Asian dust storm (ADS) period may cause difficult health problems …show more content…
In the present study, dust storm was defined according to the classification presented by Hoffmann et al [18]. In this classification, dust storms were classified in four categories (DS1–DS4, see Table 1) using the concentration of particulate matter with 10 micrometers or less in aerodynamic diameter (PM10) [18]. We defined dust storm (DS) event day when PM10 concentration was 200 µg m-3 or more during the study period. The other days were defined as non-DS event days. According to WHO air quality guidelines (AQGs) for 24-hour concentration of PM10 and to accurately distinguish the effect of airborne particles on human health, we considered non-dust days with daily PM10-concentration lower than 50 μg m−3 [19]. We extended the duration of our study to more than one season to increase the variability in ambient particulates concentration which tend to show seasonal