This sounds kind of crazy, and we don't know exactly why it happens, but the most likely explanation is called the hygiene hypothesis.

这听起来有点疯狂，我们也不知道到底为什么会这样，但最有可能的解释叫做卫生假说。

With what they called the hygiene hypothesis, they propose that the increasing use of antibacterial soaps and other products.

他们提出了所谓的卫生假设，即抗菌肥皂和其他产品的使用越来越多。

This is the hygiene hypothesis, it says growing up around a less diverse bunch of microbes can make our immune systems kinda jumpy and nervous later in life.

这是卫生假说，说的是在一个微生物不那么多样的环境中长大，可以让我们的免疫系统在今后的生活中更敏感、更警觉。

Called the hygiene hypothesis, the idea is that when the immune system isn't exposed to the familiar cast of microbes, it'll keep itself busy mounting defenses against harmless substances, like pollen.

这被称为卫生假说，这个观点是当免疫系统不能接触到一些常见的微生物时，它们就会一直增加对于无害物质的防御措施，比如花粉。

Many researchers support the so-called " hygiene hypothesis" – the theory that the bacteria, viruses and worms that enter our bodies via dirt are necessary to develop a immune system capable of fighting back against these invaders.

许多研究人员支持所谓的“卫生假设理论”——通过灰尘进入我们身体的细菌和病毒是创建强壮的免疫系统， 抵抗入侵者所必需的。

For environmental factors, there's the hygiene hypothesis, which suggests that reduced early immune-system exposure to bacteria and viruses might actually increase the risk of later developing asthma, possibly by altering the overall proportion of immune cell subtypes.

对于环境因素，有一个卫生假说认为早期免疫系统没有接触过细菌和病毒事实上会增加日后患哮喘的风险，可能是因为改变了免疫细胞亚型的整体比例。