There are a significant number of people that come for treatment who on occasion, are misdiagnosed as having asthma and seasonal allergic rhinitis (hayfever). These people might complain of the following:
Skin rashes, sneezing, irritation to the eyes, nose and throat, cough, headaches, nausea, as well as general lowered immunity and fatigue.
For some, these symptoms can be triggered by specific chemicals in their living environment and can become more obviously when replacing carpets or furnishings which in modern times, can contain Volative Organic Compounds (VOCs) including formaldehyde, acetaldehyde, along with benzene, toluene, perchloroethylene, and others.*
Thankfully, NASA has provided a list of plants that literally extract some of these chemicals from the air, the NASA Clean Air Study can be found here: https://en.wikipedia.org/wiki/NASA_Clean_Air_Study
My personal favourite? The Bamboo palm (Chamaedorea seifrizii)!
Greenpeace air study from Exeter University http://www.greenpeace.to/publications/carpet.pdf