Particulate matter characteristics, dynamics, and sources in an underground mine

<p>Particulate matter (PM) from mining operations, engines, and ore processing may have adverse effects on health and well-being of workers and population living nearby. In this study, the characteristics of PM in an underground chrome mine were investigated in Kemi, Northern Finland. The concentrations and chemical composition of PM in size ranges from 2.5 nm to 10 µm were explored in order to identify sources, formation mechanisms, and post-emission processes of particles in the mine air. This was done by using several online instruments with high time-resolution and offline particulate sampling followed by elemental and ionic analyses. A majority of sub-micrometer particles (<1 µm in diameter, PM₁) originated from diesel engine emissions that were responsible for a rather stable composition of PM₁ in the mine air. Another sub-micrometer particle type originated from the combustion products of explosives (<i>e.g.</i>, nitrate and ammonium). On average, PM₁ in the mine was composed of 62%, 30%, and 8% of organic matter, black carbon, and major inorganic species, respectively. Regarding the analyzed elements (<i>e.g.</i>, Al, Si, Fe, Ca), many of them peaked at >1 µm indicating mineral dust origin. The average particle number concentration in the mine was (2.3 ± 1.4)*10⁴ #/cm³. The maximum of particle number size distribution was between 30 and 200 nm for most of the time but there was frequently a distinct mode <30 nm. The potential origin of nano-size particles remained as challenge for future studies.</p> <p>Copyright © 2018 The Authors. Published with license by Taylor & Francis</p

Asma e fatores associados em adolescentes de 13 e 14 anos em São Luís, Maranhão, Brasil Asthma and associated factors in students 13 and 14 years of age in São Luís, Maranhão State, Brazil

O objetivo deste estudo foi estimar a prevalência de asma e fatores associados em estudantes de 13 e 14 anos do Município de São Luís, Maranhão, Brasil. Realizou-se estudo transversal utilizando o questionário do ISAAC (International Study of Asthma and Allergies in Childhood) e questionário complementar, entre julho de 2008 e maio de 2009 com 3.069 adolescentes. A prevalência de asma (sibilos nos últimos 12 meses) foi de 12,7%, sendo que 32,4% apresentaram sibilos alguma vez na vida, 3,9% tinham dificuldade de fala por causa de sibilos e 9,8% relataram sibilos após exercícios físicos. Na análise multivariada, os fatores associados à maior prevalência de asma foram história familiar de asma, infecção respiratória e sibilos no início da vida, eczema, tabagismo passivo e rinite alérgica. A prevalência de asma encontrada foi inferior à brasileira. Os fatores mais associados com a prevalência de asma foram história familiar de asma (RP = 3,86), sibilos no início da vida (RP = 4,58) e rinite alérgica (RP = 3,21).<br>The aim of this study was to estimate the prevalence of asthma and associated factors among students 13 and 14 years of age in São Luís, Maranhão State, Brazil. A cross-sectional study was conducted using the questionnaire developed by ISAAC (International Study of Asthma and Allergies in Childhood) and an additional questionnaire from July 2008 to May 2009, including 3,069 adolescents. Asthma prevalence (wheezing in the previous 12 months) was 12.7%, lifetime prevalence was 32.4%, 3.9% reported difficulty speaking due to wheezing, and 9.8% reported wheezing after exercise. In the multivariate analysis, factors associated with increased asthma prevalence were family history of asthma, respiratory infection and wheezing in early life, eczema, allergic rhinitis, and passive smoking. Asthma prevalence was lower than for Brazil as a whole. Factors most strongly associated with asthma prevalence in these adolescents were family history of asthma (PR = 3.86), wheezing in early childhood (PR = 4.58), and allergic rhinitis (PR = 3.21)