Four college students in Harbin, capital of Heilongjiang Province, have been using portable devices to monitor the city's PM2.5 pollution.

The Harbin Institute of Technology students said they were studying various aspects of PM2.5 pollution and informing urbanites of the environmental situation, in a bid to contribute to the city's pollution control.

PM2.5, or airborne particulate matter smaller than 2.5 micrometers in diameter, has been raising concerns across the country since January, when Beijing began to publicize hourly PM2.5 data.

Chinese megacities, including Harbin, have been installing monitors for collecting PM2.5 data in a timely manner.

Zhang Yanan, a nuclear engineering sophomore who leads the student monitoring team, said her group's tasks included studying changes in PM2.5 concentrations under influence of different pollution sources, characteristics of PM2.5 distributions in time and space, and influence of the heat island effect.

After nearly two months of monitoring and studying PM2.5 levels, the team made a few conclusions, finding that vehicle emissions were the biggest contributor to PM2.5 pollution and that coal plants were also one major source of PM2.5 pollutants.

The students also tried to offer advice to local people, suggesting, for example, vehicle riders not to open windows during peak PM2.5 pollution times, outdoor sports lovers not to be out from 2 to 7 p.m., and habitants living on the 10th floor or above not to open windows in afternoons.

"We designed this project originally for a college science competition on energy conservation," Gu Hao, a team member majoring in heat engineering, said.

He said the team members were knowing more about PM2.5 while working on the project, supported by the institute which financed the monitoring equipment.

Prof. Gao Jihui, who advises the team, said the students had shown great initiative in studying PM2.5 pollution. It showed their heightened awareness of environmental protection and growing concerns about living environments, which should be encouraged and supported.

Bai Yujun, an official with the city's environmental monitoring center, said the students' monitoring data could be inaccurate, as their monitoring equipment, choices of monitoring sites and monitoring methods were not in line with official standards.

Bai said Harbin had been monitoring PM2.5 since August 2011, and the city government planned to release PM2.5 readings in 2013.

Bao Jingling, chief engineer of the environmental protection bureau of Tianjin municipality, said the key to reducing PM2.5 pollution was to determine the poisonous composition of pollutants in order to cut off the sources of such pollutants.