Rospotrebnadzor explained how to choose a school uniform.

      Before the start of the school year, parents choose a school uniform, the quality of which affects the child's comfort during lessons. Clothing should be the right size, not restrict movement, and be comfortable throughout the school day. The safest uniforms are considered to be those made from natural materials—cotton, linen, wool—or blended fabrics in which they predominate. Such garments are breathable, absorb moisture, and do not cause skin irritation. Synthetic fabrics are less breathable, can accumulate static electricity, and may cause overheating. When buying, it is important to ensure that the uniform meets safety requirements. The garment should be labeled with the fabric composition, country of manufacture, date of manufacture, size, and care instructions. The presence of a certificate or a declaration of conformity confirms that the clothing has been tested for quality and safety.