Is the waterproof and antifouling T-shirt harmful?

Actually it should be hydrophobic, not waterproof. If it is waterproof, it will be as airtight as a raincoat, and if it is hydrophobic, it will be breathable. The effect is quite good! It can prevent clothes from getting wet and dirty by some common liquids in daily life, and the adhered dirt can be easily washed off with water, which is not particularly harmful and can easily cope with the splashing and adhesion of daily life liquids.