Air pollution isn’t just an environmental issue, it’s a global health crisis that affects millions of lives every year. An estimated 6.7 million people die prematurely due to exposure to harmful pollutants, making it one of the deadliest threats we face today. While this is a combination of household air pollution (~3 million) and outdoor air pollution (~4 million), what’s even more alarming is that the burden isn’t shared equally. People in low- and middle-income countries bear the brunt of outdoor air pollution, with a staggering 89% of the premature deaths occurring in these regions. The WHO South-East Asia and Western Pacific regions are among the hardest hit, where polluted air is an unavoidable part of daily life. For many, breathing clean air isn’t a given, it’s a privilege.
According to a report on cities with the world’s worst air pollution across the world, 99 of the top 100 cities with the worst air pollution in 2023 were in Asia, with the climate crisis significantly contributing to deteriorating air quality and endangering billions of lives worldwide. India accounted for the majority with 83 cities exceeding the World Health Organisation’s (WHO) air quality guidelines by more than tenfold, based on the IQAir report, which monitors air quality globally.
The study focused on particulate matter PM2.5, the smallest yet most hazardous air pollutant. Among the more than 7,800 cities analyzed worldwide, only 9% met the WHO’s air quality standard, which recommends that average annual PM2.5 levels remain below 5 micrograms per cubic meter.
While Chennai was not among the top 100 cities with the worst air pollution, the statistics for the city are not something to be happy about. Historically (from 2017), Chennai consistently exceeds the WHO recommended air quality guidelines by at least 5 to 7 times.
Figure 1: Benchmarking Chennai’s PM2.5 levels with WHO’s recommended limit. Source: IQAir, WHO
What are LEZs?
Low emission zones or LEZs are designated areas or zones within cities or regions that have restricted access for vehicles based on their emission levels. This typically applies to internal combustion engine vehicles that operate with petrol, diesel, compressed natural gas, and liquefied petroleum gas. These vehicles may either be restricted based on factors such as vehicle age, emission standard, and fuel type or allowed only after charging a fee. This kind of area based approach was brought in for regulating mobility and vehicular movement in targeted zones especially within cities as a way to combat air pollution. Beyond promoting low/zero emission vehicles, LEZs also aim to reduce congestion and decarbonize the transport sector by encouraging public transportation, cycling, walking, and other cleaner mobility options.
LEZs across the World
Globally, LEZs have not been a new concept, going as far back as 1996, where they were established as Environmental Zones in Sweden. Other European Union countries and cities adopted different phases of LEZs since, owing to the multitude of benefits they offer.
Environmental Benefits: Cleaner Air, Healthier Lives
LEZs help reduce air pollution by restricting high-emission vehicles, leading to improved air quality and better public health.
London, UK – Pioneering Clean Air with ULEZ
According to a report that evaluated the impact of the Central London Ultra Low Emission Zone (ULEZ) in its first six months of operation, roadside nitrogen dioxide (NO₂) levels dropped by up to 36% between 2017 and 2021 based on the zone they were implemented in. At the same time, none of the air quality monitoring stations located on ULEZ boundary roads have measured an increase in NO2 concentrations since the introduction of the ULEZ, thus avoiding spillover. Similarly, in the first six months after implementation CO2 emissions from road transport in the central zone in London reduced by 4% (9,800 tonnes) compared to a scenario where there was no ULEZ. When compared to 2016, this equates to a 13% reduction.
Brussels, Belgium – Air Quality Breakthrough
In Brussels, Belgium LEZs were introduced in 2018. Between 2018 and 2022, Brussels saw significant air quality improvements, with NO2 concentrations reduced by around 30% along major roads, keeping levels below the EU legal limit of 40 μg/m³ (though still exceeding the WHO recommendation of 10 µg/m³). Additionally, black carbon emissions fell by 62%, while PM10 and PM2.5 emissions decreased by 19% and 30%, respectively, highlighting the effectiveness of low-emission zones in reducing urban air pollution.
Health Benefits: Protecting Public Well-being
LEZs have shown improved air quality, which has led to significant public health benefits. Several studies conducted across the world have also shown evidence that LEZs in cities reduce heart and circulatory problems.
Europe – Cutting Heart Disease and Strokes
A comprehensive study by Imperial College London analyzed over 320 European LEZs and found a decline in air pollution-related health conditions. It also confirmed that these zones contribute to lower rates of cardiovascular diseases.
In London, policies such as the Low Emission Zone (LEZ) reduced overall health issues by 7%, with a notable 14.5% reduction in Chronic Obstructive Pulmonary Disease. The Ultra Low Emission Zone (ULEZ) in London had an even greater impact, reducing health problems by 22.5%.
Economic Benefits: Driving Sustainable Growth
LEZs promote sustainable economic growth by reducing healthcare costs due to better air quality and by fostering clean transportation industries.
Germany – Reduced Healthcare expenses
A German study analyzing hospital data from 69 cities with Low Emission Zones (LEZs) found a 2%- 3% decrease in heart-related issues and a 7%-12% reduction in strokes, with the most significant benefits observed among older individuals. These health improvements translated into estimated cost savings of 4.4 billion euros in healthcare expenses.
Milan, Italy – A Shift to Eco-Friendly Transport
Milan’s Area C congestion charge has significantly altered commuting patterns. The number of private vehicles entering the city center declined by 43% between 2011 and 2023. Meanwhile, electric vehicle usage surged from 0.1% in 2012 to 6% in 2023, and hybrid vehicle adoption rose from 5.3% to 32.3% in the same period with a steady decline in the most polluting vehicles (diesel). The latter changed from accounting for 52% of the vehicular fleet in 2012 to just one-third (33%) in 2023. These changes not only reduced pollution but also boosted the market for cleaner transportation technologies.
Figure 1: Distribution of fuel types of vehicles entering Area C in Milan from 2012 to 2023
India and LEZs
Several Indian cities have begun experimenting with Low Emission Zones (LEZs) to tackle air pollution. The Taj Trapezium Zone (TTZ) is an example of an LEZ in India, established in the 1990’s to protect the Taj Mahal and surrounding heritage sites from industrial pollution. Spread across 10,400 sq. km, the area includes Agra Fort and Fatehpur Sikri, both UNESCO World Heritage Sites. Following a 1996 Supreme Court ruling, industries within the TTZ were banned from using coal or coke and required to switch to cleaner fuels like natural gas, relocate, or shut down—marking a major regulatory push for air quality and heritage conservation. However, Agra is still faring very poorly on the Air Quality Index (AQI), due to uncoordinated urban development, shrinking green cover, rising vehicular emissions, and weak enforcement of regulations.
In Maharashtra, cities like Pimpri-Chinchwad, Pune, and Chhatrapati Sambhaji Nagar have been planning for implementing LEZs with a focus on restricting high-emission vehicles and promoting cleaner alternatives. According to a study in Pimpri-Chinchwad Municipal Corporation (PCMC), restricting older vehicle models and encouraging a shift to BS-VI vehicles in these zones, could reduce PM2.5 emissions from vehicles by up to 80% by 2030.
Ahmedabad has also been exploring an LEZ strategy for its walled city area. Given its high-density traffic and worsening air quality, a framework has been developed to balance economic activity with pollution control. Measures include managing freight movement, improving public transport, enhancing pedestrian accessibility, and encouraging electric vehicles.
While these initiatives are still in early stages, they offer promising pathways for reducing vehicular pollution and improving urban air quality in India.
LEZ toolkit for Chennai
The Low Emission Zone (LEZ) Toolkit for Chennai, developed by the State Planning Commission in collaboration with the British Deputy High Commission, is designed to help policymakers and stakeholders implement LEZs to improve air quality and reduce vehicle emissions. While the toolkit is intended to be used initially by city and state authorities in Chennai, Chandigarh, Kolkata, and Pimpri Chinchwad, it has also been designed to be applicable to other states and cities. The toolkit provides recommendations for both short-term actions and long-term strategies some of which are listed below.
Short-term actions
- Identify & Implement Pilot LEZs: Create low-traffic zones around schools and pollution-prone areas by implementing initiatives such as regular car-free days, restricted vehicle entry during peak hours, and promoting walking, cycling, and public transport.
- Enhance Public Transport & NMT Infrastructure: Enhance public transport by improving bus frequency, reliability, and coverage, while also strengthening first- and last-mile connectivity through safe, accessible pedestrian walkways and cycling infrastructure.
- Traffic Management & Enforcement: Introduce vehicle restrictions, regulate parking, and enforce emission norms. Optimize road layouts, junctions and signal operations to improve traffic flow and reduce congestion
- Awareness & Stakeholder Engagement: Launch awareness campaigns to educate the public on the health and environmental benefits of improved air quality. Actively engage with diverse stakeholders including residents, businesses, local authorities, and transport operators, to ensure better public buy-in and tailor LEZ strategies to local needs and priorities.
Long-term strategies
- Expand & Integrate LEZs: Scale up LEZ zones city-wide and integrate them into mobility plans. Align LEZ initiatives with Chennai’s broader sustainability and climate resilience goals. Integrating LEZs into city-wide planning enables long-term environmental benefits and supports the creation of healthier, more livable urban spaces.
- Strengthen Data Monitoring & Compliance: Implement Automatic Number Plate Recognition (ANPR) cameras and remote sensing devices (RSD) to monitor and regulate emissions. Improve monitoring stations and overlay air quality data with traffic patterns to identify high-risk zones.
- Stakeholder Collaboration: Foster stronger collaboration by working with transport departments, pollution control boards, local municipalities/ city administration and business communities.
- Phased LEZ Rollout: Begin with voluntary LEZs to build public awareness and encourage behavioral change without immediate penalties. Once reliable and accessible alternative transport options are in place, such as improved public transit, cycling infrastructure, or last-mile connectivity, a phased transition to a charging-based LEZ model can follow. This gradual approach can ease traffic redistribution challenges and promote public acceptance.
Conclusion
Low-Emission Zones (LEZs) are a concept worth exploring to address Chennai’s growing air pollution and traffic congestion. With high vehicular emissions, a dense urban landscape, and rising public health concerns, LEZs could contribute to cleaner air, safer streets, and more sustainable mobility. However, their implementation in Chennai comes with both challenges and opportunities. Infrastructure limitations, policy gaps, and public awareness are key hurdles, but pilot projects, effective enforcement, and stakeholder collaboration can pave the way for meaningful change. Without strong policies, viable transport alternatives, and widespread awareness, LEZs risk creating unintended mobility barriers. Therefore, a phased, well-planned approach backed by policy support, infrastructure development, public engagement, and adequate funding, could help determine whether LEZs are a viable solution for Chennai’s air quality challenges.
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