tightness is the main characteristic by which more people are choosing plastic double-glazed windows. This seemingly positive trait and is the biggest drawback of modern PVC windows. The tightness increases at times the humidity of the air in the room and reduces ventilation, which also contributes to the reproduction of spores of fungi and disease-causing microbes. Non-breathable windows limit the intake of clean and fresh air, increasing only the concentration of dust. As a result, more people are suffering from allergies, asthma, headaches and skin diseases. Polyvinyl chloride is a material belonging to the group of so-called thermoplastics. Its composition contains ethylene, which is a product of petrochemicals. In the production of plastic structures, chlorine used as a binding component is used, it is extracted from table salt. Then stabilizers and modifiers are added to polyvinyl chloride, it is the additional components that call the environmental cleanliness of the windows into great doubt. Plastic profiles may include groups of heavy metals, such as lead, which is in PVC in a linked state. Manufacturers began to refuse to use this metal in the production of plastic. Therefore, before ordering PVC structures, be sure to require a quality certificate, as plastic can be at different levels of environmental hazards. When burning, PVC frames release toxic substances: aldehydes, carbon monoxide, cresols, phenols. Windows installed on the sunny side of the building can be a dangerous source of harmful evaporation. So wonder if you should put your health in danger? Can still stop your choice on wooden structures?