A string of serious sunburn incidents has triggered experts to question the suitability and effectiveness of aerosol spray sunscreens, which have become popular in recent years.
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And tests have shown that consumers may be getting ripped off, with sunscreen only making up half the contents of a typical can.
Aerosol spray sunscreens have soared in popularity over the past three to five years because they're quick and easy to apply on squirmy children and hard-to-reach places.
But Dr Natasha Cook at Darlinghurst Dermatology Skin and Laser Clinic said too many people were mis-applying and under-applying the product, prompting her to question whether it should remain on shop shelves.
"People are unevenly spraying and skipping massive areas of skin, and if you're outdoors and there's a breeze, half of it is blown away," she said.
"Manufacturers aren't doing enough to teach how to best use it, because to achieve the SPF, you have to spray on three or four layers," she added.
"They're not bad products, they're inappropriate products and we have to question whether they should be sold because I think it's giving people a false sense of security."
Melbourne woman Briar Houston revealed last week that despite spraying the back of her legs with Banana Boat SPF 50+, they ended up blistered and swollen.
She said the one place where she used spray-on sunscreen was the one place she got sunburnt.
Georgina Bueti told Fairfax Media her husband and younger daughter Zoe had followed the instructions on Cancer Council SPF 50+ Ultra Cooling aerosol sunscreen and carefully applied the product but still became sunburnt.
"His legs were red raw. He applied it correctly, spraying it from the right distance and rubbing it into his skin," she said.
"We have a pool at home and constantly use sunscreen, and we thought we'd try the spray but it didn't do what we thought."
Professor Sanchia Aranda, chief executive of Cancer Council said the problem was that people used aerosols like mosquito repellent, when in fact a "liberal" amount needs to be rubbed in.
The public has long been taught at least a teaspoon of lotion is required for each limb and the front and back of the body, but not much has been said about aerosol spray sunscreen.
"You could spray it into your hands to make sure you're getting sufficient amount," she said.
Another problem is that the cans – either steel or aluminium – can easily heat up in the sun, reducing the performance of the active ingredients.
"Our manufacturer tells us our products have a higher ability to withstand higher temperatures before they're unstable, but yes, prolonged exposure can affect the quality," she said.
The label on every can warns users to not spray directly onto face because inhaling the contents "can be harmful".
In the US, Consumer Reports, the US equivalent of consumer group Choice, recommended parents not to use the product on their children because inhaling the ingredients could irritate their lungs, potentially triggering an asthma attack.
Though the US regulatory system and sunscreen standards are different, the US Food and Drug Administration advised the public in 2013 to not apply spray-on sunscreen while near a source of flame, after several people suffered "significant burns" in five separate incidents.
According to Choice, only 40 to 60 per cent of a typical can is sunscreen. The rest is propellant.
A tube of lotion and a can of pressurised spray, both standing upright on a shelf, may seem comparable in price and amount. But based on unit pricing, aerosol spray is the most expensive type of sunscreen.
For example, Fairfax Media found the average price per 100 ml of lotion was $7, roll-on was $15, and finger (liquid) spray was $8.
The average price per 100 gram of aerosol spray sunscreen was $10, but because only half of the can is sunscreen, the true cost is $20.
Of course, it's up to the consumer to decide whether it's worth paying more for the convenience a spray product offers.
A Therapeutic Goods Administration spokeswoman said it routinely tested sunscreens and that "all spray on sunscreens tested by TGA over the past eight years have been found to be satisfactory".
In regards to Ms Houston's case, she said its tests of Banana Boat sunscreens found no evidence of a problem. This included one spray product.
A Banana Boat spokeswoman said there were no issues with its products and no plans to announce a recall.
"Our research indicates that complaints about ineffective sunscreen can often be the result of inaccurate application and not using enough sunscreen," she said.
"With clear sprays, it is important application is given extra attention as the product is harder to see on the skin. It is also important to hold the can approximately 10 to 15cm from the skin to allow an even coverage. We also advise our customers against applying clear spray in windy areas."
