Approximately 46% of past-year This is the fourth in a series of cannabis users in Canada aged 15 and older reported using cannabis two or reports that reviews the effects fewer times during the three months prior to the survey. [...] In this report—the fourth in a series reviewing the effects cognitive functioning and mental of cannabis use on various aspects of human functioning and development health, maternal cannabis use (see Beirness & Porath-Waller, 2009; Porath-Waller, 2009a,b)—the respiratory during pregnancy and cannabis effects of cannabis smoking are described. [...] Although the rates of common respiratory by cannabis smokers causes greater inhalation and ailments of cannabis users were comparable to those of retention of combusted particulate matter, resulting tobacco smokers, cannabis users tended to have shorter in approximately three to five times the level of tar smoking histories than tobacco users (Moore et al., deposition that occurs in the lungs of t [...] However, given the damage to the air sacs in the lungs and the narrowing and harms known to be associated with tobacco smoking and blocking of the airways. [...] The synergistic effect of tobacco and marijuana smoking was Cannabis and the Lung’s Immune System well described in a population-based study that reported Defence that people who smoked both marijuana and tobacco were almost 2.5 times more likely than non-smokers Apart from the respiratory conditions caused by the to have respiratory symptoms and nearly 3 times more inhalation of cannabis smoke an