Chennai's IT corridor inhales high pollution concentrates all-time, says study

The study by IIT Madras researchers estimates that the personal exposure to minute particles is much higher in the sidewalks of the IT corridor.

File pix of the smog that engulfed Chennai last month | EPS

CHENNAI: Don't be disillusioned by Chennai's better Air Quality Index (AQI) values and get into the trap of believing city's air is clean. A new study, which is kind of a reality check, shows famed Chennai IT corridor is a pollution hotspot and people inhale high concentration of pollution all-time.

A unique location-specific approach has been taken by researchers of IIT Madras where they estimated personal exposure at sidewalks along two contrasting urban corridors in the city - Chennai IT corridor and Marina beach promenade. Multiple measurements were taken for 10 days and the results are startling.

Pedestrians waiting near the corridors and traffic intersections are exposed to higher pollutant concentrations. At IT corridor, it was observed that the PM (particulate matter) concentrations exceed the background concentration most of the time (40–100% probability), which indicate the significant contribution from the local sources.

"There is a 30–100% probability of exceeding the critical PM2.5 concentration during the morning as compared to 10–22% probability during the evening. At beach promenade, the probability was found to be highly variable depending on the meteorology and pedestrian activities. During the morning the probability of exceeding the background and critical concentration was found to vary between 6-100% and 2-97% respectively. The lowest probability (6% and 2%) was observed on the day when there was a significant precipitation. During the weekend evening, the probability of exceeding the critical concentration was found to be 98% as compared to 10% during weekdays," said the study, which was peer reviewed and published in Sustainable Cities and Society international journal.

Co-author Prof S M Shiva Nagendra, Department of Civil Engineering, IIT Madras told Express that the objective of the study was to highlight the need to shift from city specific to location-specific air quality management.

"The current study and our earlier studies show there are many hotspots in city, where the pollution levels are several time higher than other areas in the city, but largely go unnoticed. There is enough scientific evidence to establish that sub daily exposure to high PM levels can result in significant adverse health effects," Prof Nagendra said.

Summary of the PM characteristics at IT corridor and beach promenade

Location Max(μg/m3)	Pollutant	Minimum(μg/m3)
IT corridor (Morning) 144.87	PM10	14.85
IT corridor (Evening) 139.87	PM10	11.31
IT Corridor (Morning) 109.77	PM2.5	11.29
IT Corridor (Evening) 112.78	PM2.5	8.74
Beach (Morning) 82.41	PM10	12.55
Beach (Evening)  136.16	PM10	20.55
Beach(Morning)  48.08	PM2.5	7.62
Beach (Evening)  62.44	PM2.5	13.17

Note: Personal exposure trend over entire study duration shows 75% of time the pollutant concentration is close to maximum 'unheathy' levels.

Personal exposure assessment

Ph.D Scholar Jyothi S Menon, another co-author, said personal exposure assessment is more important than ambient air. "To quantify the potential impact on health, we used Multiple Particle Path Dosimetry (MPPD) model to calculate deposition fraction of PM in various regions of the respiratory pathway. MPPD is widely used world-wide in research for estimating airway particle in lungs, head and pulmonary regions," Jyothi said.

The study shows PM1 and PM2.5 dose to be highly variable in case of IT corridor during the morning. The average PM10, PM2.5 and PM1 dose at IT corridor during the morning was found to be 28.83, 7.25 and 5.49 μg (microgram), respectively as compared to 21.63, 3.6 and 2.4 μg during the evening. On contrary, the PM dose was highly variable in case of beach corridor during the evening. The average PM10, PM2.5 and PM1 dose at the beach during the evening were found to be 33.06, 7.14 and 2.39 μg, respectively as compared to 20.3, 4.83 and 3.25 μg during the morning.

Jyothi said, "We do not know what kind of health hazards these concentrates would pose because there are no standards fixed. Ours is only a sample analysis and more research need to be conducted."

The vehicular exhaust consists of particles of the smaller size range which can penetrate deep into the lungs. This is evident at IT corridor as the deposition at the pulmonary region was higher. While at beach promenade, the deposition at head region was higher which indicates the dominance of coarser particles.

The traffic-related PM exposure has been widely reported to cause various respiratory illness including Chronic Obstructive Pulmonary disease (COPD). The individuals with respiratory problems like COPD tend to have higher breathing rate as compared to healthy individuals. The breathing frequency of COPD patients is about 22% higher than healthy individuals.

Study area

1. The first location is IT corridor 3 km stretch sidewalk along high volume six-lane urban corridor beginning from Adyar and continue south towards Mahabalipuram.
2. About 30,000 vehicles ply daily on the road and popularly known as IT corridor because of this stretch passing through many IT/ITES companies.
3. The second location is a pedestrian path which lies parallel to the beach and a busy road (beach promenade). It is a 6 km stretch sidewalk along the famous Marina beach in Chennai which is one of the most crowded beaches in the country.
4. It is estimated that about 30,000 people per day visit the beach during weekdays and 50,000 people per day during the weekends and on holidays.