Mould – an age-old adversary. It has become an increasingly troublesome issue in recent years, particularly in the damp and temperate climate of an island like Great Britain. Black mould has emerged as a growing concern, impacting homes, health, and wellbeing. While mould has always been present in certain conditions, its prevalence seems to have spiked in the last five years due to a combination of factors, including changing weather patterns, modern building techniques, and rising energy costs that discourage adequate ventilation. This seemingly innocuous black fungus has now become a source of stress for many households, leading to a battle that feels harder to win with each passing year. Addressing this issue requires understanding its causes, health risks, and effective prevention strategies to reclaim control over our living spaces.
Stachybotrys chartarum microfungus (scientific name for black mould)
becomes a very common problem to deal with for homeowners and renting tenants when there is moisture present in the environment. Its growth is slow but most often revealed and exposed in damp or water-damaged properties, where building materials with great quantities of cellulose, like plaster and wallpaper, have been used.
Changes in temperatures, lack of sunlight, and ample constant humidity also contribute to its appearance.
Speaking of which, its black color is attributed to its production of melanin.
Black mould has been the topic of debates for years due to its production of mycotoxins. However, since not all strains of S. chartarum do that, black mould has been, according to Wikipedia: “inappropriately referred to as toxic mould”.
Let’s figure out how to properly deal with black mould so none of us have to find out the validity of these claims for ourselves:
CONDITIONS THAT HAVE TO BE MET FOR IT TO FORM
Mould spores are present everywhere in the environment but they are initially dormant and drift between indoor and outdoor air.
They require water to germinate, activate and accelerate its expansion. You need to be able to control moisture levels and treat water issues present in your property, otherwise mould growth is triggered in certain conditions.
Microscopic and hard to detect at first, spores in their later stages of growth appear in black and almost fuzzy patches where they colonize a larger area of the material affected by damp or condensation.
Cellulose-rich materials are a food source for black mould. Surfaces like wet wallpaper, damp carpet or a wooden flooring flooded by a knocked over water bucket combined with temperatures of 20°C - 30°C speeding up moulds’ growth, make up one scenario of ideal conditions that allow Stachybotrys chartarum to grow.
At that point you can sometimes smell it growing as well.
Another example of ideal mould-forming conditions and a second set of variables that need to occur in this process is a mix of condensation and poor ventilation. Windows, walls, ceilings and various types of organic insulations are exposed to moisture trapped in stagnant air.
Exposing your windows to harsh, cold winter air from outside and warmth of your expensive electric heaters from the inside often results in condensation that can then leak onto your wooden sills or wallpapered walls full of cellulose.
This is the same temperature differential that results in condensation on the cistern of your toilet and activation of mould spores around it.
Any surface, given enough moisture, is susceptible to mould growth.
Improperly ventilated rooms like damp attics after a roof leak that persisted for years because of your landlord's neglect or bathrooms without fans and vents trapping water vapor in the tiling grout of your shower and silicon seals of your bathtub are the most prone to mould growth.
WHERE IN THE HOUSE IT FORMS
Stachybotrys chartarum can show anywhere with sufficient moisture:
in your attic (after a roof leak)
under your bathtub (after an indoor plumbing leak)
on the facade of your property (after an outdoor drainage problem)
in your basement (where there are no windows and the air is humid and stagnant)
in your kitchen (when the steam from your kettle constantly hits the underside of your cupboards)
around your toilet (when the so called “tank toilet sweat” is caused by condensation on its cool surface)
in your living room (when you dry your wet clothes indoors)
in your laundry room (when you machine-dry your clothes but vent its air indoors)
in your actual dryer (when moisture is not able to escape through the dryer vent)
in your washing machine (when the laundry detergent leaves a residue inside the washer drum, door and seal)
in your kitchen (when there is no hood above your stove or your hood is not actually connected to anything, not serving its purpose)
in and around your air conditioning (because of the condensation)
on your walls and ceilings (when your cellulose-rich drywall, plaster and/or wallpaper gets wet)
on your windows (when temperature differences create condensation indoors)
on your grout and sealants (when large quantities of water vapor mix with poor ventilation in your lower basement bathroom)
on your furniture (when your exterior walls are poorly insulated)
on your fabrics and clothes (when you improperly store them in damp and dark wardrobes for too long)
in your fridge (when mould spores enter the seal of the door during condensation created by opening and closing the door)
MOULD PREVENTION
As mentioned in the beginning, to prevent mould, you will need to be quick on your feet and maintain control of water in any form whether it is ice melting on your driveway and affecting the state of the foundation of your house from outside, rain dripping down the facade of your house because you forgot to drain the gutters last summer, mist, vapor and condensation caused by the decrepit, single-glazed windows in the 100 years old studio you rent or ceiling leaks from your upstairs neighbor forgetting to turn off their running kitchen sink after they let their cat drink from it for hours.
immediately fix roof leaks
quickly sort plumbing issues
promptly remove any water spills
consistently maintain your gutters
use dehumidifiers in humid areas
wipe the underside of your cupboards after cooking or making tea if you do not have a proper hood
install a proper hood in your kitchen
install fans and circulate air in small spaces without windows, like bathrooms
use mold-resistant paint and/or drywall
dry your clothes outside whenever possible
make sure your dryer vents air outside
deep clean your washing machine and dryer not to spread mould further
ventilate properly and often, when it is sunny - open windows for 10 min to air your property
deep clean the seals of your fridge
store your clothes and fabrics with care
properly insulate your walls
WAYS TO TREAT IT AND KILL IT WHEN IT DOES APPEAR
chemical products
Bleach - it has been a traditional go-to solution for years but experts now WARN AGAINST its use for several key reasons:
Bleach is mostly water. Water is moisture and moisture is your enemy in the war against black mould.
Bleach is not effective on porous surfaces (wood, drywall, fabric). Water it contains seeps into the crevices of the material and creates a damp environment. The spores are released into the air when the mould is mechanically disturbed, for example when scrubbing it with a brush. Mould will eventually regrow.
Bleach - on its own - produces strong, toxic fumes that can irritate your eyes and skin as well as your respiratory system. For people already sensitive to mould or those with conditions like asthma, combining bleach with airborne mould spores can make things worse.
Bleach reacting with Stachybotrys chartarum may release toxic compounds into the air, increasing already existing health risks.
Bleach does not fix the underlying cause of the mould - excess moisture and bad ventilation.
If we have not dissuaded you and you still decide to use bleach because it is a cheaper alternative, available almost anywhere and because you are familiar with ways of using it, use it safely with these instructions in mind:
Ensure the area is well-ventilated by opening windows and doors.
Wear protective gear such as gloves, goggles, and a face mask to prevent exposure to mould spores and bleach fumes.
Avoid mixing bleach with other cleaning products, especially ammonia.
For porous surfaces, consider using vinegar instead.
Spray or apply the bleach solution directly onto the affected areas. Let it sit for 10-15 minutes to kill the mould and its spores.
Use a stiff-bristled brush or sponge to scrub the mouldy surface thoroughly.
Rinse the area with clean water and wipe it down with a damp cloth to remove any residue.
Ensure the surface is completely dry to prevent mould from returning. Use a dehumidifier or fan if necessary.
eco-friendly ways
Baking Soda (sodium bicarbonate): absorbs water vapor, cleans and deodorises mould-affected areas and it is an abrasive so you do not have to scrub for eternity. Combine with water to make a paste, apply to the affected area, leave for 30 minutes, scrub, wipe with a damp cloth.
White Vinegar: lowers the PH levels of the surfaces it is used on and disinfects it. Kills mould species and reaches inside porous surfaces. Mix with equal parts water, spray, leave for 1 hour, scrub, wipe with a damp cloth.
Vodka: kills spores due to its high ethanol (alcohol) content. Mix with equal parts water, spray, leave for 15 minutes, scrub with brush or cloth, wipe with a damp cloth.
Hydrogen Peroxide: bleaching agent, weaker than typical chlorine bleach we warned you about earlier.
Green Bleach (sodium percarbonate): bleaching agent, a compound of sodium carbonate and hydrogen peroxide, stronger than baking soda.
Tea Tree Oil: antifungal agent, kills mould. Mix 15 drops with 2 cups of water. Spray, leave for 1 hour, scrub with brush or cloth, then wipe with damp cloth. solution and let it sit for 60 minutes.
Vinegar and vodka’s effectiveness can be further increased by adding a couple drops of tea tree oil to your cleaning solution.
Regardless of your choice of product or solution, proceed with caution.
UV-C light
We have, quite extensively, gone over moisture and how you need to maintain its levels to keep the spores at bay but let's stop for a minute to think about why black mould is black in the first place and see if there is any new information we can use to find more methods of removing mould.
We briefly mentioned melanin before. It is not only giving mould its infamous black color but melanin also serves at least three important functions helping it survive:
Defense against the environment: Cell walls of the mould are strengthened by melanin that helps it resist physical, mechanical damage (you scrubbing it off the wall behind your couch, perhaps) and helps it resist drying out.
Resistance to Oxidative Stress: OS is an imbalance of free radicals and antioxidants and can lead to cellular damage of components like DNA, proteins and lipids. Melanin looks for reactive oxygen species and helps protect mould against OS.
Protection against UV-light: Mould cells seem to get damaged by ultraviolet light. Similarly to the case of bleach, you will find opinions from both sides of the fence. Some will say treating mould with UV light helps, some will say it takes a long time to work, and others that mould needs to be exposed specifically to UV-C light for at least 90 minutes to be treated properly.
professional services
DaisyFresh are turning to safer and more effective alternatives for treating mould. Mostly those mentioned in section 4 point b) of this article - natural and eco-friendly ways. Knowledge and expertise about these alternative methods combined with our hands-on experience means you can rest assured we will do everything to help you.
WHAT IT DOES TO YOUR HEALTH AND HOW TO PROTECT YOURSELF
Not everyone will be affected in the same way, depending on their current health condition, the type of mould they were exposed to, care they took when using chemicals and the extent of the exposure.
Mould itself may cause:
Respiratory Issues
Allergic Reactions
Asthma Attacks
Infections
Fatigue, Nausea, Headaches
Brain fog, dizziness, difficulty concentrating
Skin Irritation
Immune System Suppression
Nasal congestion, sinus pain, post-nasal drip
Aggravation of Existing Conditions
There is a big overlap between problems caused by the mould itself as well as the chemical sprays and solutions you will be using to remove said mould. Some of these issues will be expanded upon below, along with the way to protect yourself from them.
Chemicals you use may cause:
Respiratory Problems
You can start coughing and wheezing whenever you inhale fumes from chemicals like chlorine bleach or ammonia that enter your respiratory tracts. If you have asthma, you can make it worse, you can damage your lungs as well.
You can get headaches and become dizzy and nauseated, especially in badly ventilated spaces. Long-term you can damage your lungs, throat and mucous membranes. Protection: use N95 or P100 respirator masks.
Skin Irritation
You can crack your skin, make it red, dry, get rashes, chronic dermatitis over time or worse - chemical burns. Protection: use rubber, neoprene or nitrile gloves, long-sleeved clothing or disposable coveralls for bigger jobs.
Eye Irritation
You can damage your eyes permanently with accidental splashes or fumes. Tearing, itching and burning sensation are the first symptoms. Protection: wear safety goggles with side shields to protect your eyes.
Chemical Burns
You can get chemical poisoning or damage to your lung tissue whenever you misuse chemicals and produce toxic gases by mixing solutions. It starts with a severe cough, throat and lung irritation. Protection: coveralls, rubber boots, shoe covers, disposable hoods or caps in addition to what we already mentioned.
Allergic reactions
You can be sensitive to the chemical compounds or to the mould itself. It can be detected when you start sneezing, your nose becomes congested, eyes irritated and skin red and inflamed. Protection: before cleaning, make sure your PPE fits properly and ventilation is provided. After cleaning, throw away and do not reuse disposable protective gear or properly wash equipment that is reusable.
Impact on Indoor Air Quality
You can worsen your health by exposing yourself to residual chemicals that linger in the air after using cleaning products. Protection: Air your property properly after a job.
OTHER TYPES OF MOULD YOU MAY WANT TO FAMILIARISE YOURSELF WITH
Mould Type | Appearance | Habitat | Health Risks | Special Features |
Aspergillus | Green, yellow, white, or black; powdery | Walls, insulation, HVAC systems, damp items like food or textiles | Respiratory issues, allergies, and aspergillosis in rare cases | Very common indoors; adaptable to conditions |
Penicillium | Blue, green, or yellow; fuzzy | Water-damaged carpets, wallpaper, insulation, and spoiled food | Allergic reactions, respiratory issues | Some species used to produce antibiotics |
Cladosporium | Olive-green, brown, or black; suede-like | Wood, fabrics, carpets, HVAC ducts | Skin rashes, eye irritation, asthma, sinus infections | Thrives in warm and cold environments |
Alternaria | Dark green or brown; velvety | Bathrooms, showers, under sinks, window frames, plants, and soil | Asthma attacks, severe allergic reactions | More common in warmer months |
Fusarium | Pink, white, or red; cottony | Water-damaged carpets, wallpaper, fabrics | Skin infections, nail infections, respiratory issues; some strains produce harmful mycotoxins | Thrives in cooler environments |
Acremonium | White, pink, grey, or orange; powdery/slimy | Drywall, insulation, humidifiers | Can cause immune-compromised infections; some strains produce dangerous toxins | Found on water-damaged materials |
Mucor | White or grey; fluffy | HVAC systems, carpets, behind wallpaper | Respiratory issues; severe infections like mucormycosis in rare cases | Thrives in high humidity, spreads rapidly |
Chaetomium | White (early); grey, brown, or black (mature) | Water-damaged drywall, carpets, wood | Skin/nail infections, allergies | Produces a distinct musty odor |
Ulocladium | Black or dark brown | Kitchens, bathrooms, basements, areas with significant water damage | Allergic reactions, asthma-like symptoms | Often mistaken for black mould (Stachybotrys chartarum) |
Trichoderma | Green or white; woolly | Damp carpets, wallpaper, behind tiles | Mycotoxins harmful to humans; structural damage | Rapid growth, destructive to building materials |
Mould has always been an issue in the UK. There are diligent steps you need to take to prevent it, various solutions to remove it, and clear instructions on how to maintain your clean environment after you deal with it.
After our article you should be better prepared to handle it right. Thank you for reading.
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