Incense is widely used to counteract unpleasant odours, chase away demons, reveal the presence of gods and to satisfy gods. Incense burning has been practised for centuries. 

There are numerous forms of incenses, including sticks, joss sticks, cones, coils, powders, rope, rocks/charcoal, and smudge bundles. The principal difference between the first two forms is that the one has a slender bamboo base, onto which the mixture of incense ingredients is fastened, while the other one is without a central base. 

While the exact content of incense sticks is a trade secret, most incense is made from a blend of fragrant gums, resins, wood powders, herbs and spices.

It can take anywhere from 50 to 90 minutes to burn a stick of incense. When incense is burning, it emits smoke and fumes which contain particulate matter (PM), gas products and other organic compounds. When the incense coating section has completely burned away, the burning chokes itself at the tip of the bamboo-part of the stick. 

People who are exposed to incense fumes always inhale the entire mixture. Therefore it is tricky to single out the health effects contributed by a certain component in the fumes. There hasn’t been much recorded on the ill effects on human health directly caused by the particles in the incense smoke. It is fascinating to note that in numerous epidemiological studies, incense burning had shown no harmful effect when used correctly.

Incense burning has been known to cause air pollution as well as possible airway disease and health problems. However, many differing reports have also been documented. The effect of incense smoke on our health needs to be further studied. It is definitely advised to keep the room well ventilated when burning incense. It will effectively reduce the indoor air pollutants and therefore reduce the risk of exposure.