All About Allergens: Mold

A fundamental component of the natural world, mold can be found in cool, dark, and damp environments, where it feeds on organic material.

Outdoors, mold will often grow on rotting wood, compost piles, dead leaves, and grass. At home, mold can grow on objects or surfaces in parts of the home that retain moisture, or in areas that don’t get a lot of sun. This means that basements, bathrooms, laundry rooms, and kitchens are the most susceptible to mold growth in the home1.


Causes of Mold Allergy

Mold is a type of fungi with over 100,000 species all over the world. In order to propagate, mold releases spores that float in the air. These airborne spores are the culprit behind allergic reactions.

In a tropical climate like Singapore’s, mold-related allergies may be common all year-round, thanks to the ideal combination of hot and humid weather, as well as frequent rainfall throughout the year, especially during the monsoon season.

Types of Mold that Cause Allergy2

The different species of molds found at home are often classified according to the level of risk they pose to an individual’s health2. Of the countless species of mold , only a few dozen can actually trigger allergic reactions.

  • Hazard Class C molds are harmless. They don’t trigger allergic reactions or lead to health-related complications of any sort. These molds, however, may lead to structural damage if left to grow unchecked in building materials in the home. Chaetomium, a Hazard Class C mold, is often found in water-damaged structures3.
  • Hazard Class B molds are allergens. These molds cause symptoms like sneezing, blocked nose, or watery eyes. A type of mold in this category, the black, pepper-like Cladosporium can be found in the bathroom, on wood and fabric materials, and on painted surfaces in the home4. A similar mold, Penicillum, can be seen as blue or green fuzz on these same materials at home, as well as in spoiled fruits and bread5.
  • Hazard Class A molds are toxins. Molds under this classification may also trigger allergies, but these same molds can lead to infections or diseases in individuals with chronic lung problems or compromised immune systems. One such mold is Aspergillus , which can be found on rotting vegetation in the wild, and on dust, spoiled food, and damp building materials at home. Individuals with chronic lung disorders or damaged lungs may suffer from this fungus infecting their sinuses or their lungs.6
Outlined lightbulb with rays of light


Some types of mold can form colonies that can be seen by the naked eye, but mold itself is a microscopic organism. Just because you don’t see mold, that doesn’t mean it’s not there!

Symptoms of Mold Allergy

  • Sneezing
  • Runny nose  
  • Nasal congestion or blocked nose
  • Red, irritated, or watery eyes
  • Itchy throat
  • Wheezing or allergic asthma

Prevention Tips for Mold Allergy

Indoor Tips

    You can prevent mold growth in your home by cleaning your bathroom, laundry room, and basement as often as needed. It’s often recommended to scrub textured surfaces and the grouting in between tiles. Check inside kitchen cupboards too and underneath the sink; clean them if you see discolorations on surfaces or in various nooks and crannies. Be sure to wear protective gear (gloves, face mask) to minimise exposure to spores.
    Keep the refrigerator clean and empty its water pan on a regular basis. Get rid of rotting or expired foods promptly to help minimise mold growth.
    Use air-conditioners and dehumidifiers to keep humidity at below 50% in your home. Alternatively, you can also use an exhaust fan in the kitchen or in the bathroom to help dissipate the steam or moisture that comes from cooking and showering.
    Prolonged exposure to sunlight can get help rid of mold. Keep curtains, shades, and blinds in your home open throughout the day.

Outdoor Tips

    Like pollen , mold spores, too, can stick to your shoes, clothing or hair when you are outdoors. To prevent pollen spores from lingering in your house, be sure to remove your shoes, take a quick shower and change your clothes to remove all traces of pollen spores.3 If you’re pressed for time, be sure to, at the very least, wash your hands and face thoroughly after entering the house.
    Mold spores can thrive in a pile of dead, fallen leaves. Therefore, it is important for you to rake your yard often. However, raking can cause mold spores to linger in the air, which is why it is important for you to wear a protective mask while performing this chore.
    It is advisable for you to wear a N95 mask that is approved by the National Institute for Occupational Safety and Health (NIOSH), which will help to minimize your exposure to mold spores when cutting grass, raking leaves or digging around plants.3 You may also choose to enlist the help of a family member or friend who isn’t allergic to mold spores.
    Mold spores can also stick to bedding or clothing that is hung out to dry on the rack. As an alternative, opt to use a dryer instead.1

Solution for Mold Allergy

Mold may be inescapable, but the symptoms to mold allergy are manageable. With Clarityn® fast and non-drowsy relief, it keeps you going minus constant sneezing; runny nose; blocked nose; and itchy, watery eyes. Enjoy all-day relief and live free from allergies.


  1. Mold Allergy. Asthma and Allergy Foundation of America, Accessed November 5, 2021
  2. Mold Hazard Classes. Mold Facts, Accessed November 5, 2021
  3. Types and Classes of Mold. Si Restoration, Accessed November 5, 2021
  4. What to Know About Cladosporium Mold. Family Handyman, Accessed November 5, 2021
  5. What to Know About Penicillium Mold. Family Handyman, Accessed November 5, 2021
  6. Aspergillosis. Cleveland Clinic, Accessed November 5, 2021