Palo Santo, or Bursera graveolens, is a fragrant wood sourced from a tree native to South America. This “holy wood” has been used for centuries in traditional healing and spiritual purification practices. It is commonly used today by igniting the wood sticks to produce aromatic smoke, a process known as smudging. As its popularity has grown, questions concerning the safety and potential toxicity of this smoke for people and pets have increased.
Understanding Palo Santo’s Chemical Composition
The distinct, citrus-like fragrance of Palo Santo comes from chemical compounds stored within the wood and resin. Burning the wood releases these compounds as volatile organic compounds (VOCs) into the air. The chemical profile is dominated by terpenes, which are responsible for the wood’s scent.
One of the most abundant terpenes is limonene, which can constitute a significant portion of the wood’s essential oil, sometimes over 60% depending on the tree’s origin. Other terpenes present include alpha-terpineol and pinene. When the wood is heated or burned, these compounds vaporize. This release of terpenes and other VOCs is the source of the wood’s benefit but also the basis of its potential risks.
Toxicity Risks Associated with Inhalation
The primary health risk from burning Palo Santo stems from combustion itself, which is true for all wood smoke. Burning wood releases fine particulate matter, specifically particles smaller than 2.5 micrometers (PM2.5), into the indoor air. These microscopic particles bypass the body’s natural defenses and penetrate deep into the lungs and bloodstream.
Exposure to PM2.5 is a known contributor to respiratory irritation, coughing, and reduced lung function. Beyond particulate matter, wood smoke also contains several toxic air pollutants, including benzene, formaldehyde, and polycyclic aromatic hydrocarbons (PAHs). These chemicals contribute to the overall burden on the body’s systems. Inhalation of any wood smoke, including Palo Santo, can increase the risk of adverse cardiopulmonary effects. The concentration of these irritants becomes highest when the wood is burned in enclosed or poorly ventilated spaces, quickly degrading indoor air quality.
Safety Concerns for Sensitive Populations and Pets
The risks associated with smoke inhalation are significantly amplified for individuals with pre-existing respiratory conditions. People living with asthma or Chronic Obstructive Pulmonary Disease (COPD) may experience an exacerbation of symptoms even from brief exposure. Young children and infants are also considered a sensitive population because their airways are still developing and they breathe at a faster rate than adults.
A major concern is the safety of household pets, particularly cats, who are exceptionally vulnerable to the terpenes in Palo Santo. Cats lack a specific liver enzyme (glucuronyl transferase) necessary to effectively break down and eliminate many terpenes. Terpenes like limonene and pinene, whether inhaled from smoke or absorbed from essential oils, can accumulate in a cat’s system. This can lead to a toxic overload resulting in symptoms such as vomiting, drooling, tremors, and neurological abnormalities. Dogs metabolize terpenes better than cats but can still suffer respiratory irritation from the smoke.
Guidelines for Minimizing Exposure and Safe Usage
To minimize potential health concerns, users should prioritize effective ventilation. Always ensure a window is open or a fan is running to draw the smoke outward and allow fresh air to circulate throughout the space. The duration of burning should be limited to short periods, such as only a minute or two, to reduce the overall emission of particulate matter and VOCs.
When using Palo Santo wood sticks, they must be placed in a fireproof dish and kept out of the reach of children and pets. Essential oils derived from the wood should be used with caution, especially around animals. Palo Santo essential oil should never be ingested and must be heavily diluted with a carrier oil before topical application to prevent skin irritation.