The reasons why your snot is black after spending the day in London

Have you ever noticed that your snot is black after a day in London?

Well, don’t worry, you’re not alone. It’s actually very common to experience charcoal-coloured mucus after trotting around the capital.

In fact, it’s ok to get this, because it means your body is doing its job right and is stopping all those horrible little germs from entering your lungs.

Here’s why it happens, and a few tips to help if you’re experiencing snot noir.

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1. High levels of airborne particles

London is a busy city with high pollution levels, including dust, soot, and tiny particles from vehicle exhaust and industrial activity. Due to limited ventilation, the Underground has a high concentration of these particles.

2. Iron and brake dust in the Tube

The Underground's confined spaces trap particulate matter, including iron oxide dust from the friction of train brakes and rails. This dust can accumulate in the air and be inhaled, leading to blackened mucus as your body filters it out.

3. Smog-central

Even above ground, London’s air contains pollutants from cars, buses, and construction, which contribute to the problem. It’s no secret the city is pretty smoggy.

4. Your nose is doing its job!

Your nose acts as a natural air filter, trapping particles before they can enter your lungs. The dark colour of your snot is evidence of this filtration in action.

Tips to reduce the effect:

Wear a mask: Especially in high-pollution areas or while on the Underground.

Nasal rinses: Using a saline spray or rinse can help clear out particles and keep your nasal passages clean.

Avoid rush hours: These periods often see higher concentrations of dust and pollutants due to increased passenger traffic.

Although it’s not harmful for most people, if you experience other symptoms like persistent cough or shortness of breath, consider consulting a doctor.