Watercress is a great antihistamine and contains oils that will help fight any possible infection from damage or immune suppression.
If the mucous gets yellow-green or blackish brown this can indicate an infection. If it turns in to an infection let me know and I can give you a simple recipe to clear up pneumonia or bronchitis in a few days.
I also recommend chaparral, which is a powerful blood cleanser and it supports the adrenals to reduce chemical sensitivities.
If you have an ozone unit you can run in the house you should do this. Ozone destroys most hydrocarbons through oxidation breaking them down in to carbon dioxide, water and oxygen.