Spray sunscreen is popular due to its convenience and quick application. However, concerns arise not from the active sun-blocking ingredients—which are often identical to those in lotions—but from the aerosol delivery system. The primary issues stem from how the product is applied, how much reaches the skin, and what is released into the air. The debate over whether spray sunscreen is harmful focuses almost entirely on the mechanics of the mist.
The Unique Risk of Inhalation
The most significant concern unique to aerosol sunscreens is the danger of unintentionally inhaling the product. When dispensed, the sunscreen creates a cloud of tiny liquid and solid particles that can be breathed in by the user or bystanders. These particles can settle deep within the lungs, potentially causing irritation or respiratory issues.
The Food and Drug Administration (FDA) has requested additional data from manufacturers to fully assess the inhalation risk. Mineral-based sunscreens, which contain active ingredients like titanium dioxide and zinc oxide, are of particular concern. While these ingredients are safe on the skin, when micronized and aerosolized, they may become problematic if they reach the lower respiratory tract. Research indicates that titanium dioxide, when inhaled in high doses, is possibly carcinogenic, underscoring the importance of avoiding the fine mist.
This inhalation risk is especially pronounced for children, who are generally more restless during application and have smaller lung capacities. Spraying the product onto a child creates a cloud, increasing the chance they will breathe in the chemicals and particles. Application near the face should be strictly avoided for all users.
Ensuring Effective Coverage
A common drawback of spray sunscreen is the difficulty in ensuring an adequate and even layer of coverage. To achieve the Sun Protection Factor (SPF) listed on the bottle, sunscreen must be applied at a thickness of approximately two milligrams per square centimeter of skin (2 mg/cm²). Users often spray too quickly or from too far away, resulting in a thin, patchy coating that reduces the actual protection received.
Studies show that most people only apply between 25% and 50% of the recommended amount. This means an SPF 30 product might only provide the protection of an SPF 7.5 or 15. This user error is exacerbated on windy days, where a large portion of the product is carried away before touching the skin. Inadequate coverage is a primary reason dermatologists express caution about aerosol sprays, as it leads to sunburn and a false sense of security.
Another safety risk unique to aerosol sprays is flammability. The propellants and alcohol in the can are highly flammable, and there have been reports of individuals suffering serious burns. Consumers must allow the product to dry completely on the skin before approaching an open flame or heat source.
Differences in Spray Formulation
Spray sunscreens require a specialized chemical formulation for aerosol delivery. Unlike lotions, these products must include propellants to push the liquid out of the pressurized can. Common propellants include petroleum-derived gases such as isobutane, propane, and butane.
These propellants significantly dilute the sunscreen concentrate inside the can; some formulations contain 50% or more propellant by volume. This dilution means a user must spray for a much longer period to deposit the same amount of active sunscreen on the skin compared to using a lotion. Spray formulas also often contain a higher concentration of alcohol or other volatile solvents. While these ingredients contribute to a cooling sensation, they can cause irritation or excessive drying for individuals with sensitive skin.
Safer Application Methods and Alternatives
Users who choose spray sunscreens can mitigate the risks by adopting simple application techniques. Always spray the product outdoors and avoid using it on windy days to minimize inhalation and product loss. Hold the nozzle close to the skin, no more than a few inches away, and spray until the skin is visibly wet.
After spraying, rub the sunscreen into the skin immediately to ensure an even coating and reduce missed spots. Never spray the product directly onto the face; instead, spray a liberal amount into your palm and then rub it onto facial skin, being careful around the eyes and mouth. For reliable and measurable coverage, non-aerosol alternatives remain the preferred option. Lotions, creams, and sticks ensure the full, un-diluted amount of product is applied directly to the skin, making them dependable choices for consistent protection.