Our study findings suggest that adolescents with asthma had a significantly higher odds of smoking e-cigarettes or any substance.This may suggest a lack of knowledge of the potential harmful long term effects of smoking ecigarettes or a general perception that e-cigarettes are “safer” than tobacco cigarettes.While recent research has suggested that ecigarettes are less harmful than tobacco cigarettes,the long term effects are still unknown.Furthermore,a recent study reported that e-cigarette usage for adolescents increases the odds of smoking tobacco cigarettes in adulthood by six times,suggesting that e-cigarettes may be used as a gateway among teens.Public health campaigns and education should target adolescents and especially those with asthma to raise their awareness of the risks of all types of smoking.Results from this study suggest that adolescents with asthma are not more likely to be smoking cigarettes,water pipes or marijuana than those without asthma.As the means of smoking change,how adolescents can smoke,presents new challenges in relation to adolescent smoking and asthma.This study found that adolescents with asthma were more likely to smoke e-cigarettes than those without.The results did not change when we included any type of smoking.Our study findings can be used to target the adolescent asthma population for smoking prevention and education campaigns and to raise their awareness of the risks associated with smoking in general.Although recent studies have reported that adolescents with asthma are more likely to smoke cigarettes or water pipes,this does not appear to be the case in Ontario,after adjusting for confounding variables.While this is encouraging,our study suggests that e-cigarettes are now popular among youth with asthma.Work should continue with anti-smoking and prevention campaigns to try and further reduce all smoking rates for adolescents,with an emphasis on the unknown and potential serious long term risks associated with e-cigarettes or alternative types of smoking.Cotton has been the most important textile cellulose fibre crop for thousands of years thanks to its excellent properties.However,grow lights for cannabis common cotton cultivation requires large intensive irrigation and large amount of inorganic fertilizer and pesticides.
In addition,Dai et al.demonstrated in their investigation that global warming would bring unfavourable effects on cotton fibre length and thus the production of cotton would be reduced.In response to global pressure for sustainable resource use and production,and growing awareness for eco-friendly products,the textile industry has to be changed in this regard.Research to enhance the sustainability and eco-friendliness of cellulose textile products go in two directions.One is the identification of potential changes in the cotton production strategies such as demonstrated by Hedayati et al.and Dong et al..Another approach is looking for an alternative cellulose fibre which can offer not only high comfort properties to the consumers but also improved sustainability to the public.As an alternative to cotton,regenerated bamboo cellulosic fibres were investigated in the last decade among which are the research conducted by Basit et al.,Abro et al.and Tausif et al..More sustainable alternative to cotton fibre may be hemp as investigated by Kocic et al.,Novakovic et al.,and Petrulyte et al..For centuries,hemp has been a source of fibre and oil seed used all over the world for a variety of industrial and consumers’ products.This widespread use of hemp declined in the 20th century after World War II for several reasons.Firstly,the presence of psychoactive components in hemp became a reason to prohibit hemp cultivation in many countries.Other reason was the intensive hand labour and high cost of work.The renewed interest in hemp arose in the early 1980s mainly from ecological concerns,environmental safety and future resource balance.With this renewed interest,hemp has been undergoing a renaissance as an alternative to food crops and alternative source of renewable,no irritating,nontoxic and intrinsically biodegradable raw material for textile,paper,automotive,construction and other sectors.Sustainable potential of hemp is reflected through its intensive growth and high yield with the use of limited or no irrigation,low consumption of fertilizers and little or no pesticides.Hemp is very competitive to weeds and can improve the soil structure.In addition,hemp has bio-remediation ability e restoration of unproductive land into agricultural use with no detrimental effect on the quantity and quality of the crop.
Cherrett et al.conducted a life cycle comparison of water and energy inputs for various hemp and cotton production systems,and indicated that hemp had a lower impact in respect to energy,water and ecology.They found that the overall water requirement for the production of 1 kg of hemp fibre is 2123 L,whereas the water footprint of cotton fibres is about 10000 l/kg.In their case studies,hemp productivity levels are much greater than those of cotton.In addition,they indicated that in the Ecological Footprint context,traditionally produced hemp fibre can be two times better than cotton fibre production.By calculating the complete life cycle of production including both the direct impact of hemp production itself on the environment and the impact associated with the manufacture and transport of the inputs required in hemp cultivation,SmithHeisters confirmed low environmental impact and low inputs of hemp grown for fibre.There is also evidence that hemp can be grown as a sustainable bioenergy crop over a wide range of agronomic and climatic conditions.The potential of hemp as an attractive multifunctional crop is confirmed nowadays on the global market with more than 25000 hemp products in a considerable number of industry sectors such as paper,packaging,bioenergy,automotive,building,textile,food and pharmaceutical industry.Industrial hemp presents a good source of hemp fibres which are widely used in the innovative production of various composites as reinforcement in the form of random aligned fibres,yarn or fabric.Traditional applications of hemp fibres for textile products include technical products,like ropes and packaging materials,and clothing textiles.Nowadays,modern production offers high added-value products for specific uses,such as geotextiles,thermal and acoustic insulation products,filters and textile composites,and for high-quality clothing sector.Hemp fibre provides excellent usage performance such as good thermal and electrical properties,high water permeability,ultraviolet light blocking,anti-microbial and anti-static properties.Aforementioned positive ecological aspects of hemp together with excellent textile properties of fibre determine hemp textile fabrics as ecologically friendly and physiological friendly textiles with considerable potential for thermal comfort.It has been shown recently that bast fibres,in general,are perceived as “wearable”,“modern” and “rich” by US consumers.On the other hand,there are some drawbacks of hemp fibre such as low elasticity and low flexibility,due to which hemp fabrics have reduced softness and rough handle.
Although the comfort is a subjective concept recognized by the person wearing the clothing item,the limited deformability of hemp fibre certainly will worsen the consumer’s perception of tactile comfort while wearing hemp fabric.Zhang and Zhang proposed the treatment with chitosan and epoxy modified silicone oil to improve softness of hemp fabrics.There are few investigations aimed at improving softness,flexibility and crease recovery of hemp fabrics by liquid ammonia treatment which was found to be an effective way of improving hand of hemp fabrics.However,due to raised environmental concern an engineering approach was taken in some investigations in order to improve the tactile comfort of hemp textiles by using exclusively mechanical processing operations.Big effort has been done to produce hemp-based fabrics by mixing with cotton and wool in order to compensate for hemp limitations in terms of tactile comfort.Blending of various fibre types commonly conducts while producing yarn.The main disadvantage of these methods is the need for the same length of both types of fibres; otherwise the longer fibres will be broken worsening the yarn quality.This means that hemp fibres have to be adequately processed as cotton-like or wool-like fibre so as to be able to be processed on cotton or wool spinning systems.To avoid this,Kim and Kim utilized non-conventional spinning methods for producing hemp/tencel yarns and knitted fabrics with enhanced tactile comfort.In the investigation conducted by Stankovic,hemp yarn was folded with filament in order to produce knitted fabrics with improved compressibility.Stankovic and Bizjak examined the possibility of improving the tactile properties of hemp based knitted fabrics by yarn folding.Stankovic et al.proposed blending hemp with cotton by simply assembling two one-fibre type containing yarns.This made it possible not only to avoid chemical treatments of fabrics,but also to exclude additional mechanical operation to improve their comfort performances.In this project,an attempt was made to introduce synthetic fibre in blend with hemp by assembling hemp yarn with synthetic one in the knitting stage.Acrylic yarn was chosen to be combined with hemp component primarily because acrylic fibres are porous and soft.In the investigation conducted by Kumar,acrylic knitted fabric had an advantage over cotton counterpart in terms of fullness and softness.Bearing in mind that cellulosic fabrics are shrinkable and easily creasing,grow cannabis the addition of synthetic fibres should also contribute to the shape stability and easy-care of garments.Acrylic fibres were designed as synthetic substitutes for wool and as a precursor in carbon fibres production.
The elastic properties of acrylic fibres are comparable to wool giving the acrylic-based fabrics the wool-like hand.In addition,acrylic fibres are characterized by low shrinkage and good resiliency.Erdumlu and Saricam investigated thermal comfort properties of a wide range of acrylic knitted fabrics from the perspective of their usage in winter wear products as an alternative to wool.Van Amberet al.compared the thermal comfort properties of acrylic and wool knitted fabrics and indicated that differences detected between them were mainly linked to different hygroscopicity of acrylic and wool fibre.Even though synthetic fibres are considered to be inferior to cellulosic ones in terms of thermal comfort,it has been confirmed that the use of acrylic fibres in textile fabrics does not necessarily result in a decrease in thermal comfort thanks to their good liquid management properties.Cil et al.and Ozturk et al.demonstrated that the presence of acrylic fibre in blends with cotton improved the comfort properties related to water management of single jersey knitted fabrics.Nayak et al.investigated the thermal,moisture management and tactile comfort properties of super absorbent acrylic knitted fabrics and confirmed their potential for using them as the next-to-skin layer of fire fighters’ clothing thanks to better sweat absorption capacity and thermal comfort.Although the use of acrylic fibres has raised sustainability issues such as non-renew ability petroleum resources and low degradability under conventional conditions,Wallenberger reviewed their advantages over cellulose fibres in terms of energy savings,and some environmental aspects.In the more recent study conducted by Van der Velden et al.,the cradle-to-gate analysis from raw material extraction to manufactured textiles demonstrates that acrylic have the least impact on the environment followed by elastane,nylon and cotton.Bearing in mind the positive aspects of hemp and acrylic,the concept of creating comfortable and eco-friendly hemp-based textiles in a cleaner manner was analysed in this study.In addition,the dimensional stability of the produced knitted fabrics,as well as tested comfort properties were evaluated after the defined period of usage of undershirts in real life during which the items were not only worn but also maintained.By investigating durability of the fabrics’ properties,another sustainability aspect was included in this study.In addition to a more sustainable design approach proposed in this study which is of practical interest for textile engineers and designers,to the best of authors’ knowledge,there is no any published investigation of changes in thermal properties of knitted fabrics exposed to repeated wear and care cycles,and the only one study conducted so far included the investigation of dimensional changes by a wear trial carried out with cotton T-shirts.Therefore,this investigation tends to fill in this gap in the scientific knowledge.Hemp and acrylic,PAN,commercially finished yarns with linear density of 50 tex and twist 400 m 1 were used for knitting the single jersey knitted fabrics.Factual values of the yarns’ linear density and twist were determined according to ISO 2060 and ISO 2061,respectively.To assess the geometry of the hemp and PAN yarns,their diameter,bulk density and hairiness were determined.The diameter and bulk density of the yarns were determined for the original yarns and for the yarn samples drawn from the wet relaxed knits,as well as for the yarn samples unravelled from the knits after the wear trial test.Using a stereomicroscope SMZ800N 50 readings of diameter for the hemp and PAN yarn were taken and the average values were calculated.Bulk density of the yarns ry was calculated as ry ¼ 4T/d2 103p,where T is the yarn linear density and d is the yarn diameter.Yarn hairiness was measured for the yarns in their virgin state using SDL 103 hairiness monitor device in which yarn specimen passes over a disc-shaped adjustable guide in front of a measuring head of the device in such a way that only hairs emerging more than 3 mm from the yarn core are registered.Thirty readings were taken for both yarns and the average values of the hairiness index,defined as the number of hairs on the yarn surface per meter,were given.