Because of all the smog and pollution in China, these three get sick a lot.

China is the always the worst, because he represents the whole of the country. He coughs horribly, his eyes hurt and water, he often has panic attacks, and more.

Hong Kong and Macau are affected less than their older brother. Only when the pollution in Hong Kong and Macau is bad do they get sick. But it's the same symptoms as China's just lessened.

The only nations that know of this are the rest of the Asians, Russia, England, Iceland, and Portugal.