UK households issued black mould warning and urged to do 1 'vital' test now

UK households have been issued a black mould warning as experts urge people to carry out one "vital" test that could reveal a hidden health threat in the bathroom. The warning comes from home heating specialists at Air To Heat, who say black mould isn't just something that leaves dark stains on tiles and grout, it also releases invisible spores that spread through the air and can cause serious breathing problems.

Bathrooms are among the most vulnerable places in the home because they combine heat, damp, and poor ventilation. Steam from hot showers raises humidity, and when windows are shut or extractor fans aren't used, the conditions are perfect for mould to grow. Air To Heat said people may not even realise there's a problem because mould spores can't be seen. But once they're inhaled, they can irritate the lungs and trigger coughing, sneezing, or more serious health issues in vulnerable groups.

Children, older people, and anyone with asthma or a weakened immune system could be at higher risk.

Prolonged exposure has been linked to breathing difficulties and infections that sometimes need medical treatment.

To help identify whether spores are present in the air, the experts are urging households to try a simple home test that's gaining attention on social media.

A viral video on TikTok has shown how placing a petri dish in the bathroom for several hours can reveal whether airborne mould is present.

After it's sealed and kept in a warm, dark place for a few hours or days, any spores in the air will settle and begin to grow.

Thousands of people have now tried the test, with many sharing pictures of unexpected results in the comments.

Some admitted they had no idea spores were floating around their bathrooms.

But others, including professional mould inspectors, have warned that the test doesn't prove how serious the problem is.

Mould spores are present in most homes, they say, so it's normal to see growth in a petri dish, even if mould levels are low.

Still, the test is raising awareness of how easily spores can spread, especially during autumn and winter when bathrooms are kept hot and steamy.

Air To Heat said heating systems can make the issue worse if not paired with good ventilation.

Warm air speeds up mould growth, so it's important to balance temperature with airflow to keep spores at bay.

The experts recommend some easy ways to reduce the risk, including:

• Opening a window or using an extractor fan after showers
• Wiping down wet surfaces to remove moisture
• Cleaning corners and grout where mould often starts
• Maintaining heaters to avoid excess damp

The company said doing the test is a good first step, but prevention and airflow are key to protecting health, especially as colder months approach.