After suffering one recently I thought I would answer and look at a few of the questions and myths around the common cold:
Are you are more likely to catch a cold on a flight?
Yes. But it's not the circulating air on the plane as most people think. Simply being in a confined space with so many other people, increases the risk of germs spreading. ALTHOUGH, re-circulated air is more likely to give you sinus problems (another issue for freediving). Also, low humidity in the pressurised cabin increases the risk of infection.
Why is a cold a problem for freediving?
The cold virus is attacking the membranes of your nasal passages and your sinuses which makes them swell up and increase mucus production. This clogs up the sinus passages causing increased pressure and pain. During a dive air in the body expandes and needs to be able to move which it can't do as easily if these passages are blocked.
So we know there is no cold cure, but what can decongestant medication do?
As we all know, there is no cure yet for the common cold. Antibiotics will only fight bacteria, not viruses. Decongestants (tablets or spray) can shrink the swollen blood vessels in the nasal passages, lessening the pressure and helping with drainage.
Is it safe to freedive using decongestant medication?
Most research and advice on this topic is related to scuba diving (diving and descended under pressure for 30-45 minutes at a time). In scuba it is possible for the medication to wear off in that time causing problems on ascent. Freediving has different issues, most notably faster ascents and a lack of time to be able to stop and react if a reverse block (sinus pressure increasing from expanding air on ascent that is unable to escape the nasal cavity) occurs. Generally speaking it is risky, and anyway, if you are sick with a cold your body is fighting the infection and so is weaker and will therefore not be transporting oxygen as efficiently. Therefore you wont be feeling great and should not really be undertaking strenuous activity or pushing your limits!
Are there natural solutions for reducing congestion?
Inhaling steam such as in a hot shower or from a bowl of hot water. Adding an essential oil such a eucalyptus which has anti-inflammatory properties, can help. The hot steam dilates the blood vessels allowing increased blood flow and circulation, alleviates soreness and inflammation and liquifies mucus secretions making it easier to clear. Keeping hydrated also will allow the body to fight the virus quicker. Nasal irrigation such as a 'Neti pot' allows you to wash through the sinuses but this must be done with sterilised saline water and sterilised equipment and might feel uncomfortable if you are not used to it.
Any other options?
Snorkel!!! Most of the colour and marine life is in the top 0-10m of the sea, so you can still experience the wonder of being in the water and make the most of your holiday, even if you cannot dive down :)