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When cold air hits your lungs, it triggers a release of histamine, which causes wheezing in people with asthma. If you

're one of the many whose asthma is triggered by cold air, make sure you wrap up warm when you go outside. Wearing a scarf over your nose and mouth can help, because it will warm up the air as you breathe in. It's also a good idea to have a couple of puffs of your reliever inhaler before you step outside.

We all need to keep up our fitness routines in winter, but when cold air triggers asthma it's time for outdoor enthusiasts to switch to the gym. Don't forget to warm up for 10 minutes and take a couple of puffs of your reliever inhaler before you start.

Sneezing, runny nose, itchy eyes, coughing and a tight chest are symptoms we are familiar with from colds. But if morning congestion lasts for weeks or months rather than days, it could be a sign you have allergic rhinitis triggered by mould or mites that linger in dust – and which are at their highest levels in winter. The Royal College of Physicians says three out of four people with year-round congestion may have an allergy.

While medicines such as antihistamines, inhaled corticosteroids and nasal sprays to thin mucus can ease symptoms, making changes to your environment can make a big difference. Key culprits are cigarette smoke in your house, pets, and old carpets and bedding that trap dust. If symptoms worsen or disrupt your day-to-day life, see your doctor.

Dust mites are spider-like creatures that are invisible to the naked eye. They feed on the skin we shed while we sleep and the microscopic mould that grows on mattresses. They are found in all household dust, but mainly in bedding.

It's not the mites that cause the problem, but their droppings – which are the most common indoor trigger for allergies and asthma. Symptoms are worse between October and March because central heating and double glazing trap in allergens and create a warm, humid environment that is the perfect breeding ground for mites.