Doctors about by for from in of on over to with Canada have called about by for from in of on over to with a ban about by for from in of on over to with the use about by for from in of on over to with perfumes and aftershaves about by for from in of on over to with hospitals and clinics. They say the chemicals about by for from in of on over to with the scents can trigger asthma and allergies. Research shows that about by for from in of on over to with half of asthma attacks are caused about by for from in of on over to with irritants such as powerful smells. Besides perfumes and aftershaves, these can include cigarette smoke, cleaning fluids and other strong fragrances and odours. Dr Ken Flegel and Dr James Martin of McGill University about by for from in of on over to with Canada wrote about by for from in of on over to with the dangers of smells in hospitals in the Canadian Medical Association Journal. They said: "Hospital environments free about by for from in of on over to with artificial scents should become a uniform policy, promoting the safety about by for from in of on over to with patients, staff and visitors alike." Strong smells affect many about by for from in of on over to with us in one way or another. Around a third about by for from in of on over to with people say they are physically affected about by for from in of on over to with artificial scents worn by others. The doctors noted that this should be a serious concern about by for from in of on over to with all hospitals. They wrote: "While artificial scents are designed to make us more attractive, they may result about by for from in of on over to with unintended harm about by for from in of on over to with those who are vulnerable. There is emerging evidence that asthma, about by for from in of on over to with some cases, is primarily aggravated about by for from in of on over to with artificial scents." They added that: "This is particularly concerning about by for from in of on over to with hospitals, where vulnerable patients about by for from in of on over to with asthma or other upper airway or skin sensitivities are concentrated." They warn that scents about by for from in of on over to with hospitals can make these patients' condition worse.