Summer has finally arrived, with daytime temperatures expected to exceed 30C in large parts of central and southern England on Friday.

The UK Health Security Agency (UKHSA) has issued a level 3 health alert for London and the east and south-east of England in response, meaning action is needed to protect people elderly, people with chronic illnesses, young children and babies. .

Health teams in the Midlands and South West England have also been placed on Level 2 alert, meaning there is an 80 per cent chance that temperatures will exceed 30C.

So what are the best strategies for staying cool when temperatures soar?

Wear loose clothing with long sleeves

Direct sunlight heats the blood vessels in your skin, sending heat to your heart and raising your body temperature. Babies are particularly vulnerable because they have a high skin surface area relative to their volume. Wearing loose, long-sleeved clothing can help prevent this. It also protects against sunburn (see below).

Cool hands, face and feet

The so-called hairless skin, found on the palms of the hands, the soles of the feet and the upper part of the face, contains a special network of blood vessels dedicated to rapid temperature management. Applying cold water or an ice pack to these areas hastens the cooling of the body. Wetting the skin, with a cold washcloth for example, also helps release body heat through evaporation, which is the same reason we sweat.

Avoid cold showers

As counterintuitive as it may seem, a cold shower can help retain body heat by causing blood vessels in the skin to constrict. This undermines one of the body’s key strategies for heat loss: bringing blood closer to the skin’s surface, so heat can radiate (hence why we look red when we’re hot ). Longer immersion in cold water, like going swimming in a lake, will gradually cool the body – but cold showers tend to be quick. It is best to shower in lukewarm water as this will stimulate blood flow to the skin, increasing heat loss.

Stay hydrated

Dehydration is a big reason why heat waves are so deadly. When people lose too much fluid through sweating, the blood thickens, which increases the risk of clots and forces the heart to work harder. Profuse sweating also changes the balance of sodium and potassium in body fluids. This can affect nerve and muscle cells, putting extra strain on the heart. The key is to drink regularly throughout the day, avoiding caffeine and alcohol, which can cause you to urinate more frequently. Don’t rely on thirst, which can be an unreliable indicator of hydration status.

Keep curtains and windows closed during the day

This is especially important for south-facing rooms, where the sun streaming through your windows will turn your environment into a greenhouse. As a general rule, windows should be kept closed when it is cooler inside than outside, usually when the day is hottest, but opened once the daytime temperature drops in the evening and night .

Search for green spaces

Trees and plants absorb water through their roots and release it through their leaves through a process called transpiration. This cools their immediate surroundings, as the heat from the surrounding air causes this water to evaporate. Studies suggest that suburban areas with mature trees are 2-3°C cooler than suburbs without trees. Trees also provide much-needed shade.

Avoid sunburn

No one wants puffy, puffy skin, but sunscreen should be your last line of defense against the sun, rather than your first. Instead, use shade when the UV Index is highest – usually between 11 a.m. and 3 p.m. – cover skin with clothing and protect your head, neck and face with sunglasses and a hat with wide edges. If sun exposure is unavoidable, opt for a sunscreen with broad protection against UVA and UVB rays. The sun protection factor (SPF) only refers to UVB protection.

“We recommend a sunscreen with a minimum SPF of 30 and good UVA protection,” said Dr Tanya Bleiker, president of the British Association of Dermatologists. “Sunscreen should be applied liberally and reapplied every two hours, after swimming, exercising, or any other activity that may rub or wash it off.”