Study undertaken to determine pollution guidelines for underground metro stations

IIT-Delhi's civil engineering department has undertaken a study to help frame guidelines for air pollution in the underground metro railway stations in Delhi. Data will be collected at two metro stations—Chandni Chowk and Patel Chowk—for a year before it is analysed.

The study is a PhD project of Praveen Babu, a student of the department. Babu will collect hourly data from the two stations for eight hours a day on week days. Hourly data will be collected for 24 hours a day during the weekends. The data will be collected under three categories. Measuring concentration of pollutants will form the first category. Concentration of particles of sizes 10, 2.5 and 1 micron in the air indoor will be monitored.

The second category of data will relate to ventilation inside the stations. "The air conditioning system of the station maintains ventilation, which controls the air exchange rate between indoor and outdoor air. Due to lack of guidelines in India, we take standards set by the American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE). According to ASHRAE, 700 ppm of CO2 is allowable, while maximum limit of CO2 is 1000 ppm," said  Mukesh Khare, the professor under whom Babu is pursuing his PhD. If the CO2 concentration becomes higher, it may impact health of the people in that enclosed space. "Depending on individual physiology, people may feel nauseated and suffocated. Some may develop redness and itching in eyes," said Khare.

Thirdly, the project will look at occupancy at the stations at different times. "Occupancy will be measured between 9 and 11 am and 6 and 8 pm as these are the peak hours. It will also be measured between 12 am and 2 pm when relatively less people travel and occupy station spaces," said Khare.

The project will also measure outdoor pollution levels. Concentration of SOx, NOx and PM 10 will be measured. "We would like to see relationship between pollution levels of indoor and outdoor air. This will help us see if pollution is coming from outside to the underground stations," said Khare.

He said the two stations have been chosen because of the differences in turn-out and characteristics of people. "Patel Chowk has low turn-out and office going crowd. Chandni Chowk, on the other hand, has high occupancy and largely business class people from outskirts of Delhi like Ghaziabad," said Khare.

"The project will also involve survey of the people coming to these stations. Hundred people each from both the stations will be interviewed about health issues they face at the station.

Khare added that metros in other parts of the world have a methodology to monitor and keep pollution levels low. But as their instrumentation is expensive and climatic conditions differ, India has to develop its own methodology.