hey ... my sister is allergic to smokers , not the people , just the environment ... :) i am not sure if it is

Asthma or just allergy ... so i thought maybe if i'll discrib her symptoms you'll judge better ... oh and another thing .. my friend has told me that her exposure for smoking can lead to asthma. I do not believe in him as my sister does not smoke and also she tries to avoid whereas any person are smoking. Her exposure to smoking rises her sneezing and her nose would start to run with continuous headache. Without any exposure to smoking can a person have allergy for such thing ? is it only smoke that provoke such a reaction or may be other thing such as dense as smoke ? I have seen many who smoke heavily but still they are fit, how can it be ?