Background

Air pollution ranks among the leading environmental threats to human health globally. The World Health Organization identifies ambient (outdoor) air pollution as a major cause of mortality, attributing millions of premature deaths to it annually, as well as a significant contributor to morbidity and disability-adjusted life years (DALYs). India is among the world's fastest-urbanising nations. Each year, millions of people migrate to cities in search of educational, employment, and lifestyle opportunities, while metropolitan boundaries continue to expand, incorporating peri-urban areas into city limits. This influx intensifies demand for transport, energy, housing, infrastructure, and employment. Consequently, cities experience more vehicles, more industries, more construction, and higher emissions. The resulting increase in ambient pollutant concentrations degrades air quality, elevates carbon emissions, and poses serious risks to public health.

In 2023, the average particulate matter (PM2.5) concentration in India was 41.0 µg/m³, making it the world's second most polluted country. Air pollution shortens the average life expectancy in India by 3.5 years relative to what it would be if the World Health Organization's (WHO) guideline of 5 µg/m³ were met, amounting to a cumulative loss of approximately 4.9 billion life years. Since 1998, pollution levels have increased by 63%, further reducing life expectancy by an estimated 1.5 years. In 2019, premature deaths and illnesses attributable to air pollution resulted in economic losses of US$28.8 billion and US$8 billion, respectively. Together, this represents a total loss of US$36.8 billion—equivalent to approximately 1.36% of India's GDP. In urban areas, air pollution reduces labour productivity, increases healthcare costs for employers and households alike, and discourages investment, as businesses may be hesitant to bear the additional economic costs associated with operating in heavily polluted cities.

Mumbai, a megacity with a population exceeding 12 million—and more than 20 million across the Mumbai Metropolitan Region, which contributes over 6% of India's GDP, 25% of its industrial output, and 70% of its maritime trade—is experiencing acute air pollution driven by commercial activity, rapid construction, and increasing vehicular traffic. As a result, air pollution not only has a significant adverse impact on public health and well-being but also imposes substantial economic costs through personal financial burdens, increased government expenditure, broader societal costs, and mounting pressure on the healthcare system. Every fiscal year, Indian businesses lose an estimated US$95 billion owing to reduced productivity, workplace absenteeism, premature deaths, and morbidity attributable to air pollution.

The mean PM10 concentration in Mumbai in 2024 was approximately 115 µg/m³—almost twice the Central Pollution Control Board (CPCB) annual standard of 60 µg/m³, nearly three times the European Union's annual limit of 40 µg/m³, and more than 7.5 times the World Health Organization's guideline of 15 µg/m³. The city's mean PM2.5 concentration was approximately 83 µg/m³—more than twice the CPCB annual standard of 40 µg/m³, over three times the European Union's annual limit of 25 µg/m³, and more than sixteen times the WHO guideline of 5 µg/m³. Over the five winter seasons (October to February) between 2021 and 2026, Mumbai recorded only seven days of 'Good' air quality (daily average AQI below 50). Instead, the city's air quality was consistently dominated by 'Moderate' AQI days (101–200). In both December 2024 and January 2025, for example, Mumbai recorded 31 consecutive 'Moderate' AQI days, meaning residents did not experience a single day of either 'Good' or 'Satisfactory' (51–100) air quality across two consecutive months.

The burden of air pollution is also unevenly distributed across the city. Mumbai's air pollution is highly localised, with neighbourhoods only a few kilometres apart experiencing markedly different air quality. Industrial areas such as Mahul and Dharavi, which are also home to large low-income communities, record dangerously high concentrations of SO₂ and PM10 due to smelting, oil combustion, and coal burning. Adjacent to the Deonar dumping ground, Deonar recorded an average winter PM2.5 concentration of 80 µg/m³, while nearby Shivaji Nagar recorded 76 µg/m³. In these pollution hotspots, particulate matter concentrations are up to 60% higher than the citywide average.

Construction dust is one of the primary sources of PM10 and PM2.5 pollution in Mumbai. Experts have attributed the recent deterioration in the city's Air Quality Index (AQI) and that of its satellite cities to the rapid increase in construction activity driven by major infrastructure projects, alongside rising vehicular emissions. India's construction industry is expanding rapidly, growing at a compound annual growth rate (CAGR) of 14.2% between 2021 and 2025, and is projected to grow by a further 8.8% annually between 2026 and 2030. To meet this demand, the country is expected to add between 700 and 900 million square metres of commercial and residential built space each year.