Burning smell could be an olfactory hallucination or a real smell indicating a problem in the environment or human body.
Could be a part of olfactory aura and the most common smell reported before a migraine episode (putrid smoky odors or scent resembling smoke, burnt plastic, burning wood, burnt toast or cigarette smoke). Other less common smells include toxic-smelling aromas, sewer-like stenches and decomposed garbage.
Chemical substances associated with burning smells include sulfur dioxide and volatile hydrocarbons.
The smoky odor character is most consistently associated with hydroxy and methoxy indanones and partially with methyl and methoxy phenols. Burnt odors are associated with furans and alkyl benzaldehydes. The oxidized oily character is usually ascribed to alkenones, dienones, hydroxy cyclocarbonyls, and indanones. Irritation factors seem most frequently to be associated with the lower molecular weight phenols. Some benzeldehydes and methoxy benzenes may also contribute to this sensation. While some unsaturated aldehydes contribute to a portion of the exhaust odor complex, the most abundant exhaust aldehydes do not appear to contribute significantly. Neither sulfur nor nitrogen containing species contribute to the smoky-burnt odor complex and exhaust odors.
Ethyne, ethene and benzene were found to make up well over 80% of the non-methane hydrocarbons for efficient flame combustion of wood. The proportions for low-temperature smouldering are similar to those of environmental tobacco smoke. The hydrocarbons from wood burning differ from those in traffic-polluted urban air by higher proportions of ethene and alkadienes and lower proportions of alkanes and alkylbenzenes which are emitted as unburnt petrol components. Ethyne may be a suitable tracer hydrocarbon for emissions from efficient wood-burning installations. The high proportions of the genotoxic hydrocarbons ethene, propene, 1,3-butadiene and benzene are of concern with respect to health hazards