Incense sticks: what they are, and what they do to the air
One of the oldest continuous human practices, and one with a measurable downside that the packaging never mentions.
9 min read · Published 16 August 2026
The answer
Incense is aromatic material burned for scent, ritual or both, and it's among the oldest continuous human practices, attested in Egypt, Mesopotamia, India and China thousands of years ago, and central to Hindu, Buddhist, Catholic, Orthodox and Shinto worship today. Stick incense comes in two main forms: cored sticks, common in India, where paste is rolled onto a bamboo splint, and solid extruded sticks, common in Japan, which burn cleaner because there is no bamboo. The materials range from sandalwood and frankincense to agarwood, which is among the most expensive natural raw materials in the world. The part usually left out is air quality. Burning incense produces fine particulate matter at levels that can exceed cigarette smoke in an enclosed room, along with carbon monoxide and some volatile organic compounds, and heavy long-term exposure has been associated with respiratory harm.
From temple to shop shelf
Incense appears wherever there was trade in aromatics, which is to say almost everywhere. Egyptian temple ritual used frankincense and myrrh, both traded up the Arabian incense route at enormous cost. Chinese use is documented from at least the Han dynasty and became an art form: *xiangdao*, the way of incense, with appreciation ceremonies comparable to tea.
The Japanese tradition, *kōdō*, formalised this further into a practice of listening to incense instead of smelling it, complete with competitive games of scent identification.
In India, incense is inseparable from daily and temple worship, and agarbatti production remains an enormous cottage industry. In Catholic and Orthodox liturgy the censer has frankincense, with the rising smoke read as prayer ascending: an image shared, independently, across a striking number of traditions.
The practical origins aren't mysterious. Aromatic smoke masks unpleasant smells, discourages insects, and marks a space as set apart. All three are good reasons, and they arrived long before anyone theorised about them.
Burn it with a window open or not at all. The smoke is the part the shops don't mention.
The main types
| Type | What it is | Notes |
|---|---|---|
| Cored agarbatti | Paste rolled on a bamboo splint | Indian standard; bamboo adds smoke and a burnt note |
| Solid extruded | No core, pressed and dried | Japanese standard; cleaner burn, subtler scent |
| Sandalwood | Santalum album and relatives | Indian sandalwood is protected and heavily adulterated |
| Frankincense | Boswellia resin | Church and temple use; trees under harvesting pressure |
| Agarwood, oud | Resin from infected Aquilaria trees | Among the costliest raw materials on earth; CITES listed |
| Nag champa | Halmaddi resin with plant material | The familiar 1970s scent; halmaddi supply has declined |
| Synthetic-dipped | Blank sticks dipped in fragrance oil | Most cheap incense; the scent is perfumery, not botany |
The bottom row covers a large share of what is sold. Dipped sticks aren't fraudulent so much as unlabelled: a blank burns and a synthetic fragrance oil provides the smell, so very cheap sandalwood smells like a chemical approximation of sandalwood.
What it does to indoor air
This is the section the subject needs, and it's not an argument for never burning incense.
Combustion of any organic material produces fine particulate matter: PM2.5, particles small enough to reach deep into the lungs. Measurements of incense burning in unventilated rooms have recorded PM2.5 concentrations well above outdoor air quality guidelines, and in some studies above those from cigarette smoke in comparable conditions. Also present: carbon monoxide, and volatile organic compounds including formaldehyde and benzene depending on the material and binder.
The epidemiology comes largely from populations with heavy sustained exposure, temple workers, and households in parts of Asia where incense burns daily for hours. Studies in those groups have found associations with respiratory symptoms, reduced lung function and, in some cohorts, elevated risk of respiratory cancers. Findings aren't uniform and confounding is a real difficulty, but the direction is consistent enough to take seriously.
Proportion counts. A stick burned occasionally in a ventilated room is a very different exposure from several hours a day in a closed shrine room, and the research is mostly about the second.
Burning it more sensibly
Reducing the exposure without giving it up
- Ventilate. A window open even slightly during and after burning makes a large difference to peak concentration and to how long it lingers.
- Burn less. Half a stick is usually enough for a room, and sticks can be extinguished and relit.
- Prefer solid extruded sticks over cored ones where you can. No bamboo means less smoke for the same scent.
- Don't burn in a small closed room, and particularly not in a bedroom with the door shut before sleeping in it.
- Keep it away from where children sleep or play, and from anyone with asthma.
- Consider unburnt alternatives where the point is the scent rather than the smoke, warmed resin, essential oil, or simply the raw wood.
None of this requires abandoning a practice that's thousands of years old and meaningful to a great many people. It requires treating it as combustion, which is what it is.
How a stick is made
There are two ways to make a stick, and the difference decides what you are breathing. Masala incense is made from a paste of ground aromatic woods, resins, herbs and a binder, usually a gum from the joss tree, rolled by hand onto a bamboo splint or extruded without one. The scent is in the material. Charcoal or dipped incense starts with a blank stick of charcoal powder and binder, which is then soaked in fragrance oil, often synthetic. The scent is a coating.
Most of the cheap incense in the world is the second kind, and most of it is made in and around Bengaluru and Mysuru in Karnataka, where rolling agarbatti has been women's home work for a century. A skilled roller makes several thousand sticks a day at piece rates. The famous brands, the nag champa in the blue box among them, come out of the same industry.
The great materials
| Material | Source | Notes |
|---|---|---|
| Sandalwood | Heartwood of Santalum album, India, and Australian plantation species | Indian wild stocks protected; most 'sandalwood' incense is fragrance oil |
| Agarwood, oud, aloeswood | Resin formed in Aquilaria trees after fungal infection | CITES-listed; cultivated inoculation in Vietnam and Assam now supplies much of it |
| Frankincense | Resin of Boswellia trees, Somalia, Oman, Ethiopia | Overharvesting is degrading wild stands; prices rising |
| Myrrh | Resin of Commiphora, Horn of Africa and Arabia | Bitter, medicinal; the Egyptian embalming resin |
| Benzoin | Resin of Styrax, Sumatra and Laos | Vanilla-sweet; the base of many church blends |
| Palo santo | Bursera graveolens wood, Ecuador and Peru | Fallen wood traditionally; demand now drives cutting |
| Copal | Resins of several Central American trees | The Maya and Aztec temple incense, still used |
Three of those rows carry a supply problem, and the problem is the same in each case: a slow-growing tree, a global market, and a product sold as sacred, which discourages buyers from asking where it came from. Asking is the respectful thing to do.
Kōdō, briefly
Japan turned incense into a formal art in the fifteenth century, alongside tea and flower arranging. In kōdō one does not smell incense but listens to it, a small heated piece of aloeswood on a mica plate over buried charcoal, passed hand to hand in a cupped bowl. The ten virtues of incense, attributed to a Zen text, include that it wakes the senses, clears the mind, and is a companion in solitude.
The classical game is Genji-kō, in which five samples are heated in sequence and the players record which they judged to be the same and which different. There are 52 possible patterns of sameness among five samples, and each pattern is named for a chapter of *The Tale of Genji*. It is a memory and discrimination exercise dressed as literature, and it is the opposite of the smoke-filled room: a few grams of wood, gently warmed, never burned.
If the scent is the point
A great deal of incense is bought for the smell and burned for the ritual, and the two can be separated. A resin warmed on a heater with no flame gives frankincense or benzoin without combustion. A piece of sandalwood or aloeswood on a mica plate gives the scent kōdō is built on, with almost no smoke. An oil diffuser gives the fragrance and none of the particulates, though the oils have their own cautions around pets and children.
If the smoke itself is the point, the rising line of it in a still room, then burn less and open the window. The ritual survives half a stick. The lungs prefer it.
What the smoke is doing, fairly
Claims that incense cleanses a space of negative energy are traditional instead of demonstrated, and belong with the broader question of what energy means in these contexts. Nothing measurable is being removed.
What is happening is real enough without it. Scent is unusually strongly tied to memory and emotion through the olfactory system's direct connections to the limbic areas, so a familiar incense can produce an immediate shift in how a room feels. Lighting something and waiting is also a ritual act with a duration, and marking a transition with a small deliberate action is a helpful thing to do.
So the clear account is close to the traditional one in effect and different in mechanism: the space does change, and you're the thing that changed in it.
Three more questions
- Is burning incense bad for you?
- In quantity and without ventilation, it has real risk. Incense produces fine particulate matter at levels that can exceed cigarette smoke in an enclosed room, plus carbon monoxide and some volatile organic compounds. Studies of heavily exposed groups such as temple workers have found associations with respiratory symptoms and reduced lung function.
- Is incense worse than cigarettes?
- Some measurements of PM2.5 from incense in unventilated rooms exceed those from cigarette smoke in comparable conditions, but the comparison is easily overstated. Smoking delivers smoke directly into the lungs and involves a different mix of chemicals, and typical incense exposure is far lower than typical smoking exposure.
- What is the difference between Indian and Japanese incense?
- Indian agarbatti are usually cored, with aromatic paste rolled onto a bamboo splint, which adds smoke and a burnt undertone. Japanese incense is generally solid extruded with no core, which burns cleaner and allows subtler scents. The Japanese tradition also formalised appreciation into kōdō, the way of incense.
- How can I burn incense more safely?
- Ventilate the room during and after burning, use less (half a stick is usually enough) and choose solid extruded sticks over cored ones where possible. Avoid burning in small closed rooms, especially bedrooms before sleep, and keep it away from children and anyone with asthma.
- Does incense cleanse a space?
- Not in any measurable sense, and nothing detectable is removed. What does happen is real: scent connects strongly to memory and emotion, so a familiar incense can immediately change how a room feels, and lighting something and waiting is a deliberate act that marks a transition. The change is in you instead of the room.
- What is the difference between masala and dipped incense?
- Masala incense is a paste of aromatic woods, resins and herbs rolled onto a splint, so the scent is in the material. Dipped incense is a charcoal blank soaked in fragrance oil, often synthetic. Most cheap incense is dipped.
- What is kōdō?
- The Japanese art of 'listening' to incense, formalised in the fifteenth century. A small piece of aloeswood is warmed, not burned, on a mica plate over charcoal and passed around. The Genji-kō game asks players to distinguish five samples, with 52 possible patterns named for chapters of The Tale of Genji.
Santiago Garcias