Environmental Tobacco Smoke (ETS), or passive smoking, is commonly attributed to two components: second- and third-hand smoke [1]. Secondhand smoke (SHS) is defined as “the combination of smoke emitted from the burning end of a cigarette or other tobacco products and smoke exhaled by the smoker” [2]. Third hand smoke (THS), however, is a complex phenomenon resulting from residual tobacco smoke pollutants that adhere to the clothing and hair of smokers; to surfaces, furnishings and dust in indoor environments [3].
SHS exposure due to proximity to people smoking, leading to the unintentional inhalation of smoke has major health effects for individuals [4], leading to a population burden in both health and subsequent economic costs when prevalent [5]. It was estimated that 40% of children globally were exposed to SHS in 2004, along with 33% of adult male non-smokers and 35% of adult female non-smokers [6]. Around 600,000 deaths, the equivalent of 1·0% of worldwide mortality, along with 10.9 million disability adjusted life years (DALYs) were attributed to secondhand smoking in that year. Of these secondhand smoking related deaths, 47% occurred in women, 26% in men and 28% in children [6].
The long term effects of smoking on chronic disease are well documented, but the exposure to SHS in adolescents and children can result in more immediate harm through the exacerbation of respiratory conditions such as asthma [7] and respiratory-related school absenteeism [8]. It is imperative, therefore, that we understand both the levels of SHS exposure in this population and the determinants for it, so that appropriate preventative approaches can be developed.
Smoking by household members has been identified as the main predictor for SHS among children [9,10,11,12,13,14], with family groups and home environments particularly important. Allowing someone to smoke around you [10] is associated with SHS at home, with maternal smoking a stronger predictor than paternal smoking [11, 14, 15]. Low parental education [11, 16] along with the number of cigarettes smoked in the household [11] have also been found to be determining factors. Girls have been found to be at a greater risk of SHS exposure [9, 12], with this more common at older ages [9] and amongst those in lower socioeconomic status [12], for both sexes. Time in the week and year has also been found to make a difference, with a higher prevalence in SHS exposure found on Mondays [11, 12] and during the winter months [11, 12], than at other times. Individual factors, such as self-reported tobacco use status and a lack of awareness about the harmfulness of exposure to second hand smoking from other people [13], have also been found to increase the risk.
The majority of studies on SHS come from high income countries, with few studies collecting information on exposure to SHS among schoolchildren from lower middle-income countries [17,18,19]. Our understanding of the levels and prevalence of SHS in less affluent countries remains weak, despite this body of evidence. This is a concern as the majority of the global burden attributable to SHS exposure is thought to occur in developing countries in Southeast Asia and the Western Pacific [6].
In 2004 the estimated prevalence of SHS exposure among children in the Southeast Asian region was found to be 53% [6]. However, limited data on SHS exposure among schoolchildren in individual countries within this region remain. The Sri Lanka Global Youth Tobacco Survey (SLGYTS) [18], a national school-based survey of students in grades 8–10 (ages 13 to 15 years), conducted in years 1999, 2003, and 2007, found that exposure to SHS at home and in public places decreased over this time. In 2007, nearly one-third (29.9%) of students reported that they were exposed to SHS in their home during the 7 days prior to the data collection. However, the highest prevalence of home SHS was found in 2003 (51%), increasing from 41% in 1999, so some questions over these large decreases remain. In addition, despite this relatively low prevalence of SHS exposure in 2007, two thirds (66%) of the students reported that they had been exposed to SHS in public places, similar to the prevalence figures from 1999 and 2003 (both 68%). In a separate study, in 2012, Katulanda et al. reported SHS exposure among schoolchildren in grades 10 and 12 (ages 15 to 17 years) in the Colombo district which was lower than found in the SLGYTS at 16.3% [19]. Although this lower prevalence may reflect the impact of The National Authority on Tobacco and Alcohol Act, No. 27, of 2006 [20, 21], differences between the sampled populations of these studies must be recognized. Whereas the SLGYTS sampled from all nine Sri Lankan provinces, to gain a nationally representative sample, the Katulanda et al. study sampled only from schoolchildren in Colombo, the capital city.
The Tobacco and Alcohol Act, No. 27 of 2006, presently practiced in Sri Lanka, has provisions for smoke free environments in indoor public and private places [20, 21]. The main objective of these legal provisions is to protect the public from exposure to SHS. However, the law does not have the provision to ban smoking inside homes and exposure to SHS in homes and indoor public places remains high, despite progress in tobacco control activities [22, 23].
Exposure to SHS amongst adolescents could be a major issue in Sri Lanka due to poor implementation of the anti-smoking legislation and a lack of provision to influence smoking within homes. Substantial health gains could be made by extending effective public health and clinical interventions to reduce SHS in all areas [6]. Previous studies conducted several years ago indicated a reduction of exposure to SHS, but despite many changes in the anti-smoking legislation and approaches to reduce tobacco use, no follow up studies have been carried out. In the present study we aimed to determine the current prevalence of SHS amongst adolescents in one Medical Officer of Health (MOH) region in the country and to examine the factors that determined SHS exposure among government schoolchildren in grades 9 and 10 (ages 14 to 15 years).
