With the heatwave alert lowered, morning temperatures are dropping quickly, and days with a gap of more than 10C between afternoon and night are arriving in succession.

Wider swings unsettle blood pressure. Falling temperatures constrict blood vessels and push pressure up, and the change concentrates in the morning hours. For anyone taking hypertension medication, not skipping doses comes first.

Airways are affected too. Dry, cold air irritates them and increases coughing and phlegm, with symptoms pronounced in people with asthma or chronic lung disease. Keeping indoor humidity between 40 and 60 percent is the usual recommendation.

The basics of managing the season are simple: carry an extra layer before heading out in the morning, avoid abrupt exposure when moving between spaces of very different temperature, and keep up fluid intake. Shifting exercise to later in the day, once temperatures rise, reduces the strain.

Infectious respiratory illness among children also rises as school resumes. Hand washing and keeping symptomatic children home remain the measures with the clearest evidence behind them.

If symptoms feel different from usual, medical assessment should come before self-diagnosis. Chest pain, severe breathlessness and sudden dizziness in particular are described as signals not to be written off as seasonal.