Smoked cigarettes daily, 7.6 consumed beer weekly and 25.0 had an unhealthy diet [9]. Each of these risk factors for NCDs has a different impact on health. Adolescents with low levels of AZD-8055 biological activity Physical activity have a higher risk of hypertension [3, 5]. Sedentary adolescents have a higher risk of obesity [10]. Physical inactivity and sedentary behaviour are different constructs and represent different causes and consequences that affect health [10]. Another risk factor for NCDs that has a negative impact on the health of adolescents is unhealthy diet, either through the low Entinostat web consumption of fruits and vegetables or the high intake of foods rich in sugars that cause diabetes mellitus type II [5, 7]. Additionally, excessive alcohol use causes changes in the central nervous system that may be a cause of depression among adolescents [9]. Smoking is responsible for respiratory diseases [7, 8]. Due to the influence of different demographic and economic realities on exposure to risk factors for NCDs [7], studies with young individuals have analysed the association between these variables [8,11]. Older adolescents [11], females [8], and students of the night shift [8] are more exposed to the simultaneous presence of risk factors for NCDs. The investigation of the simultaneous presence of risk factors related to lifestyle is important because these risk factors are modifiable from changes in lifestyle. Few studies have analysed sedentary behaviour associated with other risk factors [12, 13], which are usually analysed separately in other studies. In addition, sedentary behaviour is highly prevalent among adolescents and identifying its relationship to other risk factors helps us understand and prevent the formation of habits at this stage of life [6, 14].PLOS ONE | DOI:10.1371/journal.pone.0159037 July 19,2 /Clustering of Risk Factors in AdolescentsAssessing the association between clusters of risk factors and both demographic and economic characteristics is important to identify populations with a higher risk for the development of NCDs. Thus, the aim of the present study was to investigate the simultaneous presence of risk factors for NCDs (i.e., physical inactivity, excessive alcohol consumption, smoking, sedentary behaviour and unhealthy diet) and to verify their association with demographic and economic factors among adolescents of southern Brazil.Material and MethodsThe population of this descriptive, cross-sectional and epidemiological study was composed of adolescents aged 14?9 years enrolled in public high schools of S Jos? Brazil. This study is part of a macro project entitled “Brazilian Guide for Evaluation of Physical Fitness Related to Health and Life Habits” [15, 16] and was approved by the Ethics Committee on Human Research of the Federal University of Santa Catarina (UFSC) under CAAE protocol: 33210414.3 .0000.0121. All procedures performed in the study were in accordance with the ethical standards of the national research committee, the 1964 Helsinki declaration and its later amendments as well as comparable ethical standards. Informed consent was obtained from all individuals included in the study and their guardians. The consent given on behalf of the enrolled children was written. The city of S Jos?is located in the Brazilian state of Santa Catarina in southern Brazil, and has a land area of 114.94 km2. In 2010, the city had a Human Development Index of 0.809, a percentage of young people (15?7 years old) with a complete primary.Smoked cigarettes daily, 7.6 consumed beer weekly and 25.0 had an unhealthy diet [9]. Each of these risk factors for NCDs has a different impact on health. Adolescents with low levels of physical activity have a higher risk of hypertension [3, 5]. Sedentary adolescents have a higher risk of obesity [10]. Physical inactivity and sedentary behaviour are different constructs and represent different causes and consequences that affect health [10]. Another risk factor for NCDs that has a negative impact on the health of adolescents is unhealthy diet, either through the low consumption of fruits and vegetables or the high intake of foods rich in sugars that cause diabetes mellitus type II [5, 7]. Additionally, excessive alcohol use causes changes in the central nervous system that may be a cause of depression among adolescents [9]. Smoking is responsible for respiratory diseases [7, 8]. Due to the influence of different demographic and economic realities on exposure to risk factors for NCDs [7], studies with young individuals have analysed the association between these variables [8,11]. Older adolescents [11], females [8], and students of the night shift [8] are more exposed to the simultaneous presence of risk factors for NCDs. The investigation of the simultaneous presence of risk factors related to lifestyle is important because these risk factors are modifiable from changes in lifestyle. Few studies have analysed sedentary behaviour associated with other risk factors [12, 13], which are usually analysed separately in other studies. In addition, sedentary behaviour is highly prevalent among adolescents and identifying its relationship to other risk factors helps us understand and prevent the formation of habits at this stage of life [6, 14].PLOS ONE | DOI:10.1371/journal.pone.0159037 July 19,2 /Clustering of Risk Factors in AdolescentsAssessing the association between clusters of risk factors and both demographic and economic characteristics is important to identify populations with a higher risk for the development of NCDs. Thus, the aim of the present study was to investigate the simultaneous presence of risk factors for NCDs (i.e., physical inactivity, excessive alcohol consumption, smoking, sedentary behaviour and unhealthy diet) and to verify their association with demographic and economic factors among adolescents of southern Brazil.Material and MethodsThe population of this descriptive, cross-sectional and epidemiological study was composed of adolescents aged 14?9 years enrolled in public high schools of S Jos? Brazil. This study is part of a macro project entitled “Brazilian Guide for Evaluation of Physical Fitness Related to Health and Life Habits” [15, 16] and was approved by the Ethics Committee on Human Research of the Federal University of Santa Catarina (UFSC) under CAAE protocol: 33210414.3 .0000.0121. All procedures performed in the study were in accordance with the ethical standards of the national research committee, the 1964 Helsinki declaration and its later amendments as well as comparable ethical standards. Informed consent was obtained from all individuals included in the study and their guardians. The consent given on behalf of the enrolled children was written. The city of S Jos?is located in the Brazilian state of Santa Catarina in southern Brazil, and has a land area of 114.94 km2. In 2010, the city had a Human Development Index of 0.809, a percentage of young people (15?7 years old) with a complete primary.