Mold in homes is a major problem. Recent figures from Statistics Netherlands (CBS) show that in 2024, one in five households experienced moisture or mold in their homes. Earlier, our colleague Mildred Brun wrote about Awaab Ishak, who was exposed to mold for years. His situation painfully illustrates that mold poses serious health risks, especially for children. This raises the question of what responsibility landlords bear for their tenants“ living environment. In this blog, we’ll examine how mold gets into your home and the potential health risks it poses. We’ll then describe the legal steps you can take to resolve the problem. How does mold develop in a home? Mold grows in damp places because water is necessary for its metabolism, enzyme activity, and structural integrity. Mold growth is therefore linked to the availability of moisture, expressed as relative humidity (RH) and the local moisture conditions of the surface. In general, a relative humidity of more than 70% is a prerequisite for mold growth. Mold can grow in homes on materials that both retain moisture and contain organic matter. Think of places where excessive moisture is present for extended periods, for example due to condensation, leaks, or insufficient ventilation. Porous, organic building materials such as wood, plaster, paper, cardboard, and textiles pose the greatest risk, but due to contamination with dust, grease, and skin cells, growth is also possible on materials such as concrete, stone, stucco, paint, plastic, and sealant. Mold does not so much grow on the material itself, but rather because of the material in combination with moisture and contaminants. Any surface that remains damp for an extended period and provides a food source can develop mold growth in the home. How are you exposed to mold? Mold byproducts, such as spores, fragments of hyphae, and volatile compounds released by the mold, end up in the air. This is caused by air currents, temperature differences, or movement—for example, during cleaning. People come into contact with mold through these airborne particles. Why is mold so dangerous? Because people inhale airborne particles, mold poses a particular risk to the respiratory tract and lungs. Depending on its size, mold can penetrate as far as the small airways and alveoli. This results in direct irritation of the mucous membrane, accompanied by swelling, increased mucus production, and shortness of breath due to narrowing of the airways (bronchoconstriction). Certain toxic substances produced by mold can even directly damage the mucous membranes. Most health problems arise because the immune system reacts to these substances. Common consequences include the development or worsening of allergic asthma, chronic respiratory conditions (bronchitis or COPD), and allergic rhinitis (”mold-induced rhinitis”). In rare cases, the alveoli become chronically inflamed (hypersensitivity pneumonitis), which can lead to permanent lung damage due to the formation of scar tissue in the lungs. Scientific research shows that exposure to moisture problems and mold in homes is associated with a higher risk of respiratory symptoms. This is especially true for children, but also applies to adults. Some studies have found that people living in damp or moldy buildings are up to 75% more likely to experience respiratory symptoms and asthma-related problems. In 2009, the World Health Organization (WHO) issued guidance on the dangers of mold. According to the WHO, mold growth in homes is a proven risk factor for respiratory diseases, which is why preventive measures are recommended to avoid moisture problems and mold growth. From certain