Probably, because too much naphthalene isn't very good for humans.

可能是因为吸收太多萘对人身体不好。

There's naphthalene, the main ingredient in mothballs.

樟脑丸成分是萘。

The main thing naphthalene does is vaporize, making the air smell very strongly like mothballs and therefore a lot less like urine.

萘非常容易蒸发，这就使得空气中有一股很强烈樟脑丸味道，尿液味道就不太明显。

That's because, like naphthalene, paradichlorobenzene has a very strong smell and it can interfere with some of the bacteria producing the extra smelly ammonia.

这是因为二氯苯和萘一样也有很强味道，它也可以影响产生难闻氨细菌。

In the early days of urinal cakes, probably around the turn of the 20th century, the little slabs were mostly made of naphthalene, AKA, olden-day moth balls.

大概在二十世纪初时候，早期芳香块是萘，也就是以前樟脑丸。

Many urinal cakes these days are made of a compound called a molecule that looks a little bit like a throwing star and is often used as a naphthalene replacement in moth balls.

现在芳香块成分是二氯苯，一种看起来像是飞镖一样化学分子，通常在樟脑丸中作为萘替代品使用。