In the Bay Area, there are heavy restrictions on smoking cigarettes in public, and stringent guidelines for when residents can burn waste or use their fireplaces. Barbecues are also coming under attack for their emissions. But that mainstay of the bohemian boudoir — incense — has remained under the radar of health-conscious consumers and air-quality regulators alike. Yet evidence is mounting that those who frequently burn incense, or are regularly exposed to its smoke, may be at risk for a variety of health problems.
In general, the public isn't aware of what's released into the air when incense is burned. Most brands are manufactured in India and China and they combine plant resins, wood powders, perfumes, and oils with glue containing formaldehyde and phthalates. When burned, this combination releases polycyclic aromatic hydrocarbons — highly carcinogenic compounds — into the air, along with various gases like carbon monoxide, sulfur dioxide, and nitrogen dioxide. Incense burning also produces volatile organic compounds, such as benzene, toluene, and xylene, which have long been known to cause respiratory irritation and can even trigger DNA mutations. The gases and particulate matter permeate rapidly through indoor spaces, leaving toxic residue long after the flame has gone out. This is certainly not the purification process advocated by religious mystics.
Incense is ritually burned in some Christian churches, and is a daily habit for Hindus and Buddhists making offerings or meditating. Lila Singh, who works at Kathmandu Imports on Solano Avenue where traditional Nepalese incense is sold, lights a stick every morning. "It brings luck and purifies and cleans the air," she said.
Nancy Karpani Rakela, a member of the Ananda Meditation and Yoga Center in Berkeley, says that she uses incense because it builds an association with relaxation. "If you smell it every time you meditate, you just associate it with your practice. It also masks other smells and helps you focus on your breath," she said. Rakela, who is also an acupuncturist, acknowledged that her meditation center had to stop using incense in public sessions due to complaints. "But if you burn a little stick, it's not really pollution. It's fine essences and uplifting oils, and I would only think of it as beneficial," she said.
Laura Camp, who teaches yoga at Flying Yoga in Oakland, admits that she did use it in the past, "but people complained of allergies and asthma and I had students who had to leave the class, so over the years I stopped using it." Other yoga instructors are catering to the allergic and asthmatic. Sarah Jenness, an instructor at several Oakland yoga studios, says that incense is a very personal preference, and isn't appropriate for a public space. "Many of my students struggle with chemical sensitivities, so I fully support a fragrance-free studio environment," she said.
Thomas Rivard, who is the manager of Air Quality, Noise and Radiation at the San Francisco Health Department, reports that the Tobacco Enforcement team receives numerous complaints about burning incense, particularly from multi-unit apartment buildings where the smoke travels between walls and through ducts into several properties. But because there are no restrictions on incense, these complaints have to be resolved neighbor to neighbor. "The health department would like to see less exposure to particulate matter in general. It's clearly better to have a lower exposure than a higher one," he said.
In a study published in the medical journal Cancer in 2007, Dr. Jeppe Friborg of Statens Serum Institute in Copenhagen followed 61,320 Chinese men and women who had nearly daily exposure to incense smoke. His findings revealed that they had an increased risk of getting squamous cell carcinoma and cancers of the upper respiratory tract, mouth, sinus, throat, and larynx. Numerous other studies over the past decade have confirmed the toxic constituents of incense smoke, and the American Cancer Society has likened incense exposure's impact to second-hand cigarette smoke. One disturbing study found that pregnant mothers who are exposed to burning incense at least once a week double the chance that their child will develop leukemia.
Incense manufacturers are not legally required to list product ingredients on packaging, so it's impossible to discern what you might be combusting. And because you can pick up your joss sticks at reputable health food stores like Berkeley Bowl, Rainbow Grocery, and Whole Foods, the myth that incense purifies the air and promotes healthful practices is perpetuated. But not all incense is equally toxic. If it's made entirely from organic materials it isn't likely to contain carcinogens. But since it is still not smoke-free, it's as hazardous to your health as any wood-burning fire.
Juniper Ridge is an Oakland-based company that produces incense labeled "environmentally-friendly." The packaging touts its lack of charcoal and potassium nitrate, which is a toxic component of fertilizers and gun powder frequently used in other brands of incense. And, unlike other brands, Juniper Ridge deliberately omits spiritual language in its marketing.
Sales Manager Alli Darling acknowledges that there's a paradox in the incense industry. "The natural products world has had to grow up a lot in the past thirty to forty years, but the one product that has not had to do much updating is incense. There are just no regulations about it, and no one prints ingredient lists," she said. But, she said that Juniper Ridge does divulge its ingredients: ground wood, tree sap, and vegetable-based gum. These all-natural materials are also gathered in the wild — they're pruned and foraged from regional woodlands. So the incense isn't going to create a typical hippie haze. "The experience is more like taking a walk in the woods," she said.
But for those who need that Nag Champa to relax, the new thinking seems to be that the less frequently you burn it, the better, and it's best to be mindful of where the smoke goes. "Incense makes some people really sick," said Rivard. "You should do the best you can to accommodate them. Burn it in a location that is truly private," he said.