Blue skies return to Beijing but there are questions to be answered

This is what Beijing can learn from foreign countries or cities about fighting smog

Los Angeles

Like Beijing today, LA in the last century went through a rapid rise in population and an economic boom.

In 1963, the government passed its first Clean Air Act, which mandated government at federal and local levels to get involved. In 1970, it passed its first emission standards for cars.

Get the public sector and ordinary people involved to make sure that the government's held accountable. Private groups and civil society played important roles as whistle-blowers and watchdogs.

UK

For five days in December 1952, thick smog descended on London, contributing to the deaths of an estimated 4,000 people.

The legacy of the Great Smog was the Clean Air Acts of 1956 and 1968. These introduced smokeless zones in urban areas, with a tall chimney policy to help disperse industrial air pollutants away from built up areas into the atmosphere.

In 1995, the Government passed its Environment Act, requiring the publication of a National Air Quality Strategy to set standards for the regulation of the most common air pollutants. Published in 1997, the National Air Quality Strategy set commitments for local authorities to achieve new air quality objectives throughout the UK by 2005.

Tokyo

One of the measures that Japan uses to treat air pollution is urban landscaping. Rules prescribe that each building in Tokyo must have green areas, and green plants must be planted at the top of every block.

Trees instead of grass and flowers are widely planted in the green belts.

An environmental act took effect in 2003, requiring every car be installed with a filter system and that diesel engine cars were forbidden to hit the roads in Tokyo.

Philippines

Manila is one of the polluted cities in the country, where over 2,000 people die from air pollution each year. Statistics have shown that 80% of air pollution is attributed to emissions from vehicles.

The government has mobilized a people's war against bad air - people can report vehicles with excessive discharge via text message

The government has invested greatly in vehicles burning natural gas and gas stations. Favorable policies and loans are shifted to natural gas car buyers.

Brazil

As one of the world's emerging economies, Brazil experienced severe pollution in the 1960s and 1970s due to emissions from chemical factories.

The government has added environmental protection entries into legislation and harshly punishes violators.

Meanwhile, cooperation between individuals, enterprises as well as government agencies, has been urged to protect the environment. Economic growth was put under social development.