The Hong Kong government on Thursday began releasing hourly readings of the smallest, most dangerous pollution particles, as it bowed to public pressure for greater transparency about air quality.

The Environmental Protection Department released real time updates of fine suspended particulates known as PM2.5 on its website, as measured at 14 locations around the southern trade hub.

A spokesman said the department had been monitoring the fine particles, which are considered more damaging to health than larger particles, since 1999 at a limited number of stations, without releasing the results publicly.

Levels of PM2.5 in Hong Kong fell by 17 percent from 2005 to 2011 as a result of control measures implemented by the Hong Kong and Guangdong provincial governments, he added.

"We will continue to collaborate with the Guangdong provincial government on emission reduction measures to further reduce the levels of particulates and other pollutants in Hong Kong," the spokesman said in a statement.

New PM2.5 monitors had been acquired in anticipation of the inclusion of the fine particles as a "criteria pollutant" in proposed new Air Quality Objectives announced by the government in January in response to strong public pressure.

"The installation and testing of the new PM2.5 monitors has now been completed," the spokesman said.

Hong Kong was embarrassed in January when Beijing responded to a vocal online campaign over poor air quality and began publishing readings of fine particles.

That move only came after the US embassy in Beijing began publishing its own fine particle readings on its Twitter feed, leading many residents of the Chinese capital to rely on the American figures rather than the official ones.

Roadside pollution levels in Hong Kong were the worst ever last year, according to official figures.

Measurements in the Central, Causeway Bay and Mong Kok districts indicated that pollution levels were 10 times worse than in 2005 on more than one day out of every five.

A recent ranking of cities by the World Health Organisation in respect of PM2.5 placed Hong Kong -- which competes with Singapore as Asia's banking powerhouse -- at 559th out of 566 cities.