Plant Therapy describes the aroma as a cool, crisp and clean frosty winter forest, and that is exactly what it is. Six oils, no filler: Siberian fir, rosalina, black spruce, cypress, spearmint and Virginian cedarwood. This is the neat blend rather than the roll-on, so it is undiluted and it goes in a diffuser or into a carrier oil of your choosing.

The maker puts the diffusion rate at two to three drops per 100 mL of water, or a personal inhaler. For skin, dilute to 3 to 5 percent in a carrier and apply to the chest and under the nose. It carries Plant Therapy's KidSafe, Pregnancy Safe and Nursing Safe designations, read from the maker's own published safety row rather than inferred, and keeps two to three years. Ten millilitres, a third of a fluid ounce, amber glass.

Want it ready to use? The pre-diluted roll-on, $13.99