The diarist John Evelyn wrote in 1661 about the dreadful smoke from coal fires in London that was so bad that “Her Inhabitants breathe nothing but an impure and thick Mist, accompanied with a fuliginous and filthy vapour ... corrupting the Lungs, and disordering the entire habit of their bodies, so that Catharrs, Phthisicks1, Coughs and Consumptions rage more in this one City than in the whole Earth besides.”
Fuliginous usually means sooty but it can also refer to a sooty or dusky colour (“the whole body is of a rather light fuliginous or brownish grey”, which is in a description of the bird called Bonaparte’s shearwater) or to some noxious vapour said in old medical texts to be formed by combustion within the body and which affected the head in particular (“It is not amiss to bore the skull with an instrument to let out the fuliginous vapours” — The Anatomy of Melancholy by Robert Burton.)
The word is from Latin fuligo, soot, which has also been used in English with the same meaning. Fuligo ligni is the Latin for wood soot, a form of charcoal; it was once listed in the British Pharmacopoeia as an antispasmodic, for instance to help with the treatment of whooping cough.
1 Phthisick has appeared in many spellings; it refers to conditions or diseases of the lungs, such as asthma, bronchitis and tuberculosis. It could also refer to a sufferer from any of these. It looks as though it might be linked to physic, medicinal drugs or the art of healing, but that has a different origin. Phthisic, as dictionaries now spell it (said as /ˈ(f)θɪzɪk/), is a near relative of phthisis (said as /ˈ(f)θʌɪsɪs/), an old term for tuberculosis and similar conditions; it comes via Latin phthisicus, consumptive, from an even older Greek verb, phthinein, to decay.