Chennai faces a unique pollution challenge – pollution levels that appear to be low or moderate, but are not so. | Centre for Science and Environment

Chennai faces a unique pollution challenge – pollution levels that appear to be low or moderate, but are not so.

Actual impacts can be much more severe – says CSE analysis

  • Unlike other mega cities, Chennai represents a different pollution challenge. Its annual average pollution levels -- though lower than other mega cities -- still vary between moderate to critical. Without the sea breeze in this coastal city, the peaks could have been worse

  • Analysis by CSE exposes steady and rapid increase in pollution levels, high local impacts and high traces of toxics making its air dangerous to breathe

  • Despite having better multi-modal public transport compared to many other mega cities, motorization rate is high. If two-wheelers are added then its personal motorization rate exceeds that of Western cities

  • CSE’s assessment shows how car-centric infrastructure – flyovers, signal-free roads, foot overbridges – are converting zero emissions walk trips to long motorized trips adding enormously to pollution

  • Over the last two decades, share of bus and train ridership has dropped drastically. The share of personal vehicle trips has increased 

  • Chennai needs to quickly scale up public transport, integrated multi-modal transport options, car restraint policies and walking for clean air

Chennai, August 6, 2013: According to this year’s Global Burden of Disease estimates, one-fifth of deaths across the world occur from outdoor air pollution. Also, outdoor air pollution is the fifth leading cause of deaths in India. These alarming pieces of information have drawn everyone’s attention and forced experts to take stock of pollution trends in India’s cities – including Chennai.

A recent analysis of Chennai’s air quality, done by Centre for Science and Environment (CSE), the New Delhi-based research and advocacy body, indicates that though Chennai shows deceptively low to moderate pollution levels because of its location near the sea, local impacts and exposure are high and the pollution levels are rising steadily, thereby increasing public health risks.

CSE released the findings of its analysis here today at a stakeholder workshop conducted in association with the Tamil Nadu State Pollution Control Board. Bhure Lal, chairperson of the Supreme Court’s Environment Pollution (Prevention and Control) Authority, and Anumita Roychowdhury, executive director-research and advocacy, CSE addressed the participants.

Said Roychowdhury: “Chennai’s case is different from the trends observed in other high-growth mega cities where overall ambient air pollution is very high. But this must not breed complacency as detailed scanning of available pollution data as well as research studies point to steady and rapid increase over time, high local impacts and high traces of toxics making Chennai’s air dangerous to breathe. This demands more rigorous scrutiny of air pollution profile and aggressive action in this rapidly motorizing city.”

CSE findings – the key highlights

Annual average levels of particulates increasing rapidly: Though lower than other mega cities of India, a rapid escalation in levels has been witnessed: PM10 levels have increased from 32 microgramme per cu m in 2007 to 94 microgramme per cu m in 2011 (a 193 per cent jump) – increasing at 29 per cent a year. 

Annual average levels of nitrogen dioxide increasing at a more rapid rate than PM10: Between 2007 and 2011, NO2 levels rose from 9 microgramme per cu m to 24 microgramme per cu m -- an increase of 166 per cent, at 60 per cent a year. An official source apportionment study in Chennai carried out by IIT Madras under the aegis of the environment ministry attributes 63 per cent of nitrogen oxides to vehicles. 

Pollution hotspots inside the city: In localities like Kathivakkam, Manali and Thiruvottiyur the daily average pollution levels go up 1.3 times the standards. The peak levels can be as much as 2 to 2.42 times the standards.

Studies indicate high traces of carcinogenic toxins: A group of air toxins that are not part of official routine monitoring have been studied by the scientists of Department of Environmental Management, Bharatidasan University, Tiruchirappalli in Ambathur, Kolathur, Saidapet, and Egmore areas. Results published in 2011 show high levels of polycyclic aromatic hydrocarbons (PAH), a group of toxic carcinogens. Average concentration of particle-associated PAHs ranged from 325.7 to 790.8 nanogramme/cu m, which is alarming. The same study found more toxic compounds, among them benzo-a-pyrene -- an indicator of carcinogenic risk – varying between 6.8 and 16.4 nanogramme/cu m, exceeding the national standard for annual average of 1 nanogramme/cu m. PAHs are known to come more from diesel vehicles. There is a need to spruce up air quality monitoring to track these toxins.

There cannot be any room for complacency about comparatively lower level of particulates in Chennai. Though the overall particulate levels are comparatively lower than other regions in the country, they are much above WHO guidelines. Global assessments now available from the Global Burden of Disease estimates show that the most of the health effects occur at lower levels. Chennai has several local pollution hotspots, and road side exposures are also high. Annual averages do not help address the risks. Air quality monitoring would need to address these challenges and issue health advisories to people. There is therefore absolutely no reason to think that the risk in southern cities like Chennai is lower than other cities. In fact, a health study released by the Health Effects Institute in Chennai and Delhi in 2011 shows that in Chennai, there is a 0.4 per cent increase in risk per 10-µg/m3 increase in PM10 concentration. In Delhi, it is 0.15 per cent – thus Chennai indicates a higher impact.

Vehicles are a special problem

High exposure to vehicular fumes: Vehicles pose a special challenge. In terms of actual exposure, people are more vulnerable to vehicular fumes while traveling and in close proximity to roads. Pollution concentration in our breath is 3-4 times higher than the ambient air concentration. In densely-populated cities, more than 50-60 per cent of the population lives or works near the roadside where levels are much higher. This is very serious in low income neighbourhoods located close to roads. Road users, public transport users, walkers and cyclists are the most exposed groups – they are also the urban majority.

Vehicles contribute hugely to air pollution: Source apportionment studies carried out in Chennai by Madras IIT under the aegis of the Ministry of Environment and Forests show vehicles contribute 14 per cent of particulate matter and 68 per cent of nitrogen oxides. Some other studies show that 35 per cent of PM2.5 in Chennai comes from vehicles -- tinier the particles higher the share of vehicles.

Chennai records very high exposure to vehicular pollution: A study carried out by scientists of University of Berkeley published in Environmental Science and Technology in 2012 shows that the exposure to vehicular fumes (in terms of population-weighted intake fraction, or the grams of vehicle pollution inhaled per grams of vehicle pollution emitted) in Chennai (72) is one of the highest in cities studied in India – third after Kolkata (150) and Delhi (100).

Leapfrog technology to address diesel emission which is a class 1 carcinogen: India is motorising at a level of technology and fuel quality that can compound health risks. There are special concerns about growing use of poor quality diesel. The International Agency for Research on Cancer (IARC), a wing of the WHO, has said that diesel engine exhaust can certainly cause cancer, especially lung cancer in humans. This finding comes at a time when India has failed to adopt a clean diesel road map, prevent use of under-taxed and under-priced toxic diesel in cars. 

Mobility crisis
Explosive numbers: Vehicle population increased from less than 5 lakh in 1991 to more than 30 lakh today. Cars are 20 per cent and two-wheelers 55 per cent of the total vehicular fleet. Two-wheelers and cars are 31 per cent of the total travel trips and approximately 75 per cent of the total vehicular fleet on road. Two-wheelers saw a phenomenal growth from 4 lakh in 1991 to 21.6 lakh in 2009..Average vehicles per household have increased from 0.25 to 1.26. It is said about Chennai that if we add two-wheelers, then personal motorization in the city is higher than that of Mexico City. An average of more than 800 new two-wheelers is registered every day in the city.

Learn from Delhi’s experience. Delhi has not been able to solve its problem of pollution and congestion by building more roads and flyovers for cars.  Delhi is most privileged to have more than 21 per cent of its geographical area under road space. Delhi has built the maximum roads and flyovers. Yet its roads are totally gridlocked. Peak hour traffic has even slumped to below 15 km/hour. Cars and two-wheelers in Delhi occupy 90 per cent of the road space but meet less than 20 per cent of the travel demand. More roads are not the answer.

Sign of congestions: Level of congestion on arterials and other major roads has increased eight-fold over the period 1984 to 2008. According to the estimates of the Chennai Corporation there were 10 key arterial roads in 1993-94 with journey speed of 31-40 km/hour. Now only 3 roads have this kind of speed. Similarly, there were only 2 roads with average peak hour journey speed  of 11-20 km/hour then. Now the number of roads in the class has increased to 20. Not only the vehicles taking over road but also the urban space to meet the insatiable demand for parking. 

Cars meet miniscule of travel demand yet car centric infrastructure getting priority: In Chennai cars meet only 7 per cent of the daily travel demand and two-wheelers as much as 26 per cent. This means the majority are either using public transport or walking and cycling. This will steadily undermine multi modal public transport which is a comparative strength of Chennai. This requires immediate intervention to scale up, reinvent and redesign the sustainable modes to protect the public transport, and walking share – a rich legacy of the city.

Erosion of public transport ridership: Over the last two decades share of bus, train and bicycle ridership has dropped drastically in the city. The share of personal vehicles trips have increased. Cycle rickshaws have totally vanished from the city, negatively impacting the last mile connectivity. Significant increase noted in the share of two wheeler trips followed by car trips. 

CSE checked out the impact of car centric infrastructure on pollution and carbon emissions in a few locations. This is diagnostic. Car centric infrastructure (signal free roads, flyovers and foot over bridges etc) increases interferes with walking accessibility, increases travel distances, encourage more motorized travel, and lead to more emissions.  For example, access to Tamil Nadu State Pollution Control Board is impeded due to signal free corridor and a fly over. The detour increases the car distance from the study point from 600 meters of walking access to close to 4km car ride.  This makes one petrol car emit about 0.024 gram of extra PM and a diesel car about 0.24 gram of PM -- 10 times higher than petrol car. At the same time the cars depending on the engine size emit heat trapping carbon dioxide of about 504 to 592 grams of CO2 depending upon car engine capacity. Similar issues have been noted in other locations including Alandur Road, Anna Salai to Guindy Metro station, Travel distance- 4 Kms taken by car. The cumulative impact of the detour on the traffic volume can be enormous. Such impacts must be assessed for traffic impact assessment of any road engineering projects.

Prevent gated design: Gated community is closed to general traffic by a gate across the primary access, and are surrounded by fences and walls that further limit public access. These are isolated, exclusive and insulated urban forms and the immediate fallout is increased distances, dependence on personal vehicles and increased energy and pollution intensity of travel for the residents in and around. This is grossly against the professed policy principles of the habitat standards under the National Climate Action Plan and TOD.

Whiff of change:  It is encouraging that civil society action in Chennai and responsive policies of the Corporation has also led to identification of 71 Bus route roads for improvement of the footpaths and designing of them. This would need to be built to scale. The city has also made elaborate plans of expanding different forms of public transport. These would require detailed multi-modal integration plan. To optimize the use of public transport systems last mile connectivity needs to improve. 

Challenges of bus reforms: The emerging data shows that even though bus numbers have increased from 3260 in 2008 to 3637 in 2012-13 (3365 in 2013), the passengers carried per day that initially was 47.76 lakhs in 2008-09 increased to 55 lakh in 2010-11 but then dropped to 48 lakh in 2012-13..This is disturbing as buses play a crucial role in the mobility transition. Cities need well managed, well organised modern buses that deliver efficient public transport services at affordable rates. Cities need buses because these allow greater flexibility, greater geographical coverage, cost effectiveness, and space efficiency. New bus routings can flexibly and easily meet the needs of changes in demography and land use in cities. It can also cover areas with lower travel demand. A bus occupies twice the road space taken by a car but carries 40 times the number of passengers. Bus can displace anywhere between 5 and 50 other vehicles and allow enormous oil and pollution savings.  

However, bus reforms and investments are just not about buying new buses but about efficient deployment of reliable and attractive services. Cities require immediate improvement in service level of bus service in terms of frequency, reliability, coverage, reliable information, ITS enabled passenger information service, improvement in ticketing system, bus priority, signaling, GPS enabled deployment strategy, among others. These service conditions will have to be fulfilled. 

Buses expected to pay more for diesel than cars: For cars the prices are increasing slowly – 50 paise at a time. But for the bulk buyers like buses this has been hiked by Rs 10 per cent. High fuel costs are a very important input of operations. For MTCL in Chennai, fuel costs constitute almost 28% of total costs and half of the operational costs (as of 2011). This will have to be addressed. This will also require improvement in fuel economy of buses. 

Higher fuel costs and declining fuel economy of the bus fleet is compounding costs: Over the years fuel efficiency of the bus fleet is on decline. Buses are using more fuel to do the same kilometer. It has dropped from more than 4.45 litre per km in 2007 to less than 4.3 km/litre in 2011-12.

Buses made to pay more taxes than cars: In fact CSE review shows that almost all state governments tax the buses higher than cars. This will have to be reversed. Currently bus operations are treated as commercial operations and taxed high. But cars will have to be taxed higher than buses. CSE’s review shows that in Chennai a car costing around Rs.4 Lakh-Rs.10 Lakh pays a life time tax in the range of Rs.40, 000-Rs.1,00, 000 (Rs.2,666.66- Rs.6,666.66 per annum). But a stage carriage bus with a seating capacity of 40 pays a tax of Rs. 64,000 per annum with a surcharge of Rs.16, 000 making the total tax Rs.80, 000 per annum. 

Poor bus usage and inadequate para transit is pushing commuters more towards two-wheelers: Affordability of bus and para transit (autos) play a crucial role in reducing migration from public transport to personal vehicles like two-wheelers. Increase in bus fares and expensive autos will increase dependence on two-wheelers. The operational cost of a two wheeler is as low as Re 1 to Rs 2 per km.  This will have to be addressed. 

Parking crisis: Personal vehicles not only overwhelm road space but also make competing demand on public land for parking. CSE estimate shows that the new annual registration of cars create demand for additional land for parking equal to 117 football fields. The 2008 Wilbur Smith report for the ministry of urban development indicate that in Chennai about 27 per cent of the road length is being used for parking. This is quite substantial given the big road network in Chennai and much higher than Bangalore (17 per cent), Delhi (14 per cent) and Kolkata (19 per cent). Even as the city scales up its public transport alternatives it also requires to design a parking policy to reduce usage of personal vehicles. This will require good enforcement of on street parking and effectively priced parking along with good parking management strategies. 

Make livable cities to cut toxic emissions
CSE’s ongoing opinion survey in Chennai reveals that majority feels that air pollution is worsening and vehicles are largely to be blamed for it. Action on air pollution has begun in Chennai but needs to gather momentum. The first generation action includes successive introduction of Bharat Stage I-II-III emissions standards, introduction of LPG in autos, notification of lubricant standards for two-stroke engines, bypass heavy duty trucks during day hours, strengthening of pollution control efforts in other sectors and so on. 

The pollution challenge demands second generation action to keep ahead of the problem. The city has the chance to plan its future growth differently and avoid the path of pollution, congestion and energy guzzling. More road space is not the answer. It needs to make maximum investment in redesigning the existing road space and travel pattern and achieve compact urban form to provide the majority of the people affordable and efficient mode of public transport that can be an alternative to personal vehicles. It is time to set new terms of action. Soft options have all been exhausted. 

 Strengthen air quality, health monitoring and risk communication: Review the monitoring network keeping in mind the growth in pollution, unique challenges of the city, population exposed and newer challenges like ozone, PM2.5 and toxics. It should strengthen its monitoring grid, deploy air quality forecasting modes, must regularly and systematically monitor the health indicators. At the same time implement an air quality index system and health advisory for informing people about ill effects of poor air quality.

• Demand tighter fuel quality and emissions standards roadmap: As the Union government firms up the Auto Fuel Policy road map for the country the city governments must demand stringent roadmap for public health security. The future vehicle stock are going to be much larger than the legacy stock. Also strengthen emissions checks on in-use vehicles and make a paradigm shift in inspection and maintenance programme. 

• Scale up and accelerate bus transport reforms. Integrate public transport, and non-motorised transport. Cities need to integrate bus, cycling, walking and para-transit systems. The composite plan to scale up, modernize and integrate public transport and non-motorised transport must begin to roll immediately. Different forms of public transport planned for the city may remain sub optimal if they are not well integrated and made accessible. 

• Build pedestrian infrastructure and improve access: The government should mandate pedestrian plans and make it conditional to infrastructure funding. Investments must be linked with explicit pedestrian and cycling plans. The relevant laws will have to be harmonised and strengthened for more direct legal protection of pedestrian space and rights. We need a comprehensive Road users act for targeted pedestrianisation; segregation of space by users; system of penalty to prevent encroachment in pedestrian space; prevent usurpation of pedestrian space for motorised traffic without proper justification. Implement walkability audits. Public transport plans must include pedestrian plan for multimodal integration. Need zero tolerance policy for accidents.

• Promote compact city design, consistent with the principles of National Habitat Standards for Transportation: These standards have been made by the ministry of urban development to provide for compact, high density, mixed land use development near new or existing public transportation infrastructure that includes housing, employment, entertainment and civic functions within walking distance of transit. Pedestrian-oriented design features are needed. The 12th Five Year Plan of the MOUD has also taken on board the principles of integrated landuse and transport planning.

• Design parking policy to reduce usage of personal vehicles: It is more important to promote public, common and shared parking to maximize its utility and reduce pressure on land. This should be managed and designed in a way that it caters to the requirement of the residents as well as the incoming traffic induced by the mixed land use in the area. The focus should also be on improved design for shared and common public spaces. Combine good parking management with effectively priced parking and remove parking subsidies. Experience from around the world shows that parking controls, parking pricing along with taxes top the list as the first generation car restraint measures worldwide. 

• Use tax measures to discourage personal vehicle usage and inefficient use of fuels: Remove the tax distortion between buses and cars. 

• Set up public transport fund to meet the cost of transition


For more details or for interviews, please contact Papia Samajdar at



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