A boy runs to join his schoolmates as they wait for their teachers to lead them to the train at Hengshui Railway Station.

Stay or leave?

For many migrant workers in Beijing, the abundance of job opportunities is the reason they have chosen to stay in the capital.

Zhang Ying, a 22-year-old from Guizhou province who works at an Internet company, said she does not like Beijing as a city and only stays because of the employment opportunities.

She isn't planning to buy an apartment or have a child, so the fact that she doesn't have Beijing hukou isn't a concern for her. "Even though the authorities are trying to limit the size of the population, most of the time it really doesn't make much difference to your life whether you have hukou status or not," she said.

However, the heavily polluted air means she won't stay in the capital longer than necessary.

Wu Weihua, a 34-year-old express delivery courier, said he has never even dreamed about being able to settle in the capital: "Whatever kind of new system they introduce, I know it won't help migrant workers like me."

Wu's 9-year-old son attends a primary school in his hometown in Shaanxi province, and Wu is planning to leave the capital next year. "I came here eight years ago with just a train ticket. Now, I have a new house in my hometown, and I'm also planning to buy a car and drive it home," he said.

In his eight years as a courier, Wu has become familiar with most parts of the capital, but he has never really felt he belonged: "I am just passing through. I don't need any reminders to know that."

Liu Chaoyang remains hopeful that the authorities will relax the population-control policy at some point in the future.

"I don't see why I should be kicked out. I have paid taxes for 12 consecutive years, and I have purchased property here," he said. "If I had any other options I wouldn't stay. The fact is: I don't."