At its simplest, incense is two things: an aromatic material, and a way to heat it. Traditionally, that aromatic material comes from wood — sandalwood, agarwood, cedar — along with barks, roots and resins like frankincense, myrrh and benzoin, sometimes lifted with a flower note like rose or jasmine. In East Asian incense-making, these ground materials are bound together with a natural plant-based binder — makko or kabu no ki in Japan, nanmu powder in China — mixed with water and shaped into a stick, cone or coil. Indian incense more commonly uses a resin binder called halmaddi, rolled around a bamboo core. Where things go wrong is when that natural aromatic material is replaced, in whole or in part, with synthetic fragrance oils derived from petrochemicals — a substitution that has nothing to do with price and everything to do with sourcing, and one that a beautiful box and a convincing scent can hide completely.

When incense burns, it releases a handful of familiar categories of compound: carbon monoxide, sulfur dioxide and nitrogen dioxide; polycyclic aromatic hydrocarbons, or PAHs, formed by incomplete combustion; volatile organic compounds, or VOCs; and fine particulate matter, the same category of pollutant released by candles, wood fires and diesel exhaust. At high, sustained exposure, each of these is a genuine health hazard — that part isn't in question. What is in question is dose. Most of us already live with low-level daily exposure to these same compounds from traffic, cooking and construction dust, and regulators set thresholds below which they're considered tolerable. 

A great deal of the alarming incense research comes out of temple studies — measuring air quality inside Taiwanese and Hong Kong temples, or tracking the respiratory health of long-term temple workers exposed to incense smoke for hours a day, every day, for years, often in poorly ventilated spaces. That data is genuinely concerning, but it describes a category of exposure — occupational, near-constant, often from low-grade bulk incense — that has very little in common with someone burning a stick or two at home in the evening.

The household-level research is thinner and more mixed. A large analysis of over 60,000 people in Singapore found a statistical link between incense use and respiratory cancer risk, though the researchers themselves described it as weak rather than strong. A separate look at the same dataset found no increased risk of kidney disease for people who used incense occasionally, or even daily for under twenty years — the risk only rose, by around 25%, for daily users of more than two decades. Other studies, including ones from Hong Kong, found no association at all between incense exposure and respiratory symptoms, and confirmed that cigarette smoking — not incense — was the dominant risk factor for lung cancer in the populations studied. Taken together, the honest reading is: there's no conclusive evidence that moderate household incense use is harmful, but there's also no serious researcher suggesting hours of unventilated exposure is a good idea. Moderation and airflow are doing a lot of the protective work here.

It's also worth noting what almost none of these studies accounted for: the actual composition of the incense being burnt. Researchers routinely flagged this as a limitation of their own work, because most of the incense sold — and especially the incense burnt in bulk at temples — is inexpensive, mass-produced, and often padded out with synthetic fragrance. No study to date has systematically compared all-natural incense against synthetically enhanced incense, which leaves an open and fairly obvious question: how much of the "incense risk" reported in these studies is really a "cheap, synthetic incense risk" in disguise?

Generally, no. Tobacco smoke is inhaled directly and deeply into the lungs, in a habit that for most smokers means several cigarettes a day; incense smoke is typically burning some distance from the face, diluting into a room before a much smaller portion is ever inhaled, and the average incense user is lighting one to three sticks a day at most. Animal studies comparing the two have found cigarette exposure significantly reduced fertility markers where comparable incense exposure did not. There is one frequently cited study claiming incense smoke is more toxic than cigarette smoke — but it's worth knowing its lead researcher was affiliated with a tobacco company, which is reason enough to treat the conclusion with some scepticism.

This is where reputation earns its keep. When a house like Astier de Villatte hand-rolls its incense on Awaji Island — Japan's traditional home of incense craft — or a Tokyo perfumery like APFR builds a stick around a considered scent architecture, or Aesop extends its ingredient philosophy from skincare into incense, or Shoyeido — a house with roots stretching back over two and a half centuries — releases a rare aged-wood incense sourced from aloeswood that has matured for years before it's ever burnt, none of this is really about packaging. It's about a brand with a name to protect choosing, deliberately, not to cut a corner that a customer would never see.

These houses have spent decades — in Shoyeido's case, centuries — building trust with people who burn incense every day, and a single batch of synthetic, headache-inducing incense would undo far more goodwill than it would ever save in ingredient cost. That accountability is precisely what tends to get lost at the cheap end of the grocery-store shelf, where a stick is priced low enough that no one expects — or checks for — real sandalwood, real resin, or a natural binder. The price itself becomes a kind of permission slip to stop asking what's actually inside.