Heat and Haze: Air pollution worsens in Indian cities during summer

Additionally, the PM2.5 average in 35 cities exceeded the National Ambient Air Quality Standards (NAAQS) limit of 60 micrograms per cubic metre (µg/m³). The analysis, conducted between April and June 2024 by Pune-based Respirer Living Sciences (Respirer), used primary data collected from the Central Pollution Control Board (CPCB) portal to assess air quality during these summer months.

“Our findings indicate a significant increase in PM2.5 levels in numerous cities this summer, challenging the perception that air pollution is only a winter concern,” said Ronak Sutaria, CEO and founder, Respirer.

City Rankings: Assam’s Byrnihat recorded worst PM2.5 levels this summer

The data from Respirer’s analysis platform, AtlasAQ, showed that Byrnihat located near the Meghalaya-Assam border recorded the highest average PM2.5 levels at 116.35 µg/m³, falling into the ‘poor’ category, according to the CPCB. Despite being part of the National Clean Air Programme (NCAP), Byrnihat's levels exceeded the NAAQS limit for approximately 73% of the summer days. However, it managed to decrease its summer PM2.5 levels by about 17% compared to the summer of 2023.

"Byrnihat's high pollution levels highlight the growing air quality crisis in Northeast India, driven by industrial activities and inadequate pollution controls. The industrial town…has recorded high pollution levels throughout the year, and even during summer," said Sutaria.

Faridabad and Gurugram in the National Capital Region followed Byrnihat with averages of 104.88 and 95.5 µg/m³, respectively, both categorised as 'poor'. Faridabad experienced a substantial increase in PM2.5 levels of 94.9%, shifting from 'satisfactory' to 'poor'. “This rise is attributed to vehicular activity, construction dust, and meteorological factors prevalent in the National Capital Region,” said Sutaria.

The role of industrial activities combined with growing urbanisation are the main causes of high summer pollution. “Increasing pollution levels in regions like NCR highlight the need for stricter measures and consistent monitoring throughout the year," added Sutaria. "It's critical to implement and enforce policies that can mitigate these issues, especially during the summer months."

Among the cleanest cities was Tirupur in Tamil Nadu, with PM2.5 levels at just 12 µg/m³. This stark contrast underscores the varying air quality conditions across different regions of India.

The top 10 polluted cities in the summer of 2024 in terms of PM2.5 levels are:

Byrnihat, Assam: 116.36 µg/m³

Faridabad, Haryana: 104.88 µg/m³

Gurugram, Haryana: 95.56 µg/m³

Mandi Gobindgarh, Punjab: 92.21 µg/m³

Ballabgarh, Haryana: 90.35 µg/m³

Muzaffarnagar, Uttar Pradesh: 85.11 µg/m³

Sri Ganganagar, Rajasthan: 85.03 µg/m³

Charkhi Dadri, Haryana: 84.51 µg/m³

Patna, Bihar: 82.87 µg/m³

Rohtak, Haryana: 81.76 µg/m³

45% of NCAP cities showed a rise in PM2.5 during summer 2024

The NCAP, launched in 2019, is a long-term, time-bound strategy targeting a 20-30% reduction in PM2.5 and PM10 levels by 2024, using 2017 as the base year. Extended to 2026 with a 40% reduction goal, NCAP focuses on 131 non-attainment cities, those that have consistently failed to meet the NAAQS, and implements city-specific action plans.

Out of the 131 NCAP cities, data was available for 100 cities on the CPCB’s website, the Respirer analysis said. Among these, 59 cities or 45% showed an increase in PM2.5 levels, while 31 showed a decrease compared to the previous summer. Monitoring stations were unavailable for the remaining cities in the previous year.

“After completing 5 years of NCAP, the limited monitoring coverage of just 75% of NCAP cities having reliable and comparable long-term monitoring data also reflects the fact that the existing monitoring network is not adequate. Alternate scientifically validated and scalable solutions need to be adopted to get an urgent and immediate understanding of the scale and magnitude of the challenge affecting us every day,” said Sutaria.

Delhi, ranked 13th overall and 6th among NCAP cities with a PM2.5 value of 79.25 µg/m³, saw an increase of 22.4% from last summer.

"These findings from NCAP cities reveal that despite ongoing efforts, air quality is still deteriorating in many regions. Separate investigations need to be part of city action plans to identify and address the dominant pollution sources in each city," added Sutaria.

Troubling trend for multiple pollutants across diverse regions during summer

In addition to PM2.5, Respirer monitored several other pollutants, including particulate matter (PM10 - larger coarser particles of 10-micron size), nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), and ozone across cities.

The findings reveal troubling trends that extend beyond particulate matter. For instance, Sri Ganganagar, Rajasthan recorded the highest PM10 levels, increasing by 21% from the previous year to 298 µg/m³, making it the most polluted city in terms of PM10 this summer.

The analysis also showed significant increases in NO2 levels, with Chengalpattu in Tamil Nadu and Dhanbad, Jharkhand experiencing substantial rises of 593% and 505%, respectively. SO2 levels, although below the NAAQS limit, saw increases in Imphal, Manipur, and Raichur, Karnataka. CO surged in Vijayapura, Karnataka, and Siwan, Bihar, reflecting the worsening air quality. Ozone, another critical pollutant, increased in 127 out of 262 cities, with Baddi in Himachal Pradesh and Ujjain in Madhya Pradesh showing sharp rises.

“Increases in NO2 have been mainly due to intensified industrial activities and traffic emissions while SO2 is linked to industrial emissions and coal burning. Meanwhile, the surge in CO can be attributed to vehicle emissions and urban sprawl whereas the sharp rise in ozone is likely from higher temperatures and vehicular pollution," explained Sutaria.

The latest State of Global Air 2024 report shows that air pollution remains a critical health risk in India, being the second leading risk factor for death globally and responsible for 8.1 million deaths in 2021. This includes deaths from noncommunicable diseases like heart disease, stroke, diabetes, lung cancer, and COPD. For the first time, the report includes data on NO2 exposure, highlighting its impact in densely populated urban areas where traffic emissions are significant. South Asia, including India, bears some of the highest burdens of air pollution-related health impacts.

Air pollution leading cause of cardiovascular deaths in India: Doctors

Air pollution has emerged as the most powerful cause of cardiovascular deaths in India, surpassing traditional risk factors such as hypertension, diabetes, and lipid profile, said doctors.

BB Bharati, member of the executive committee of the Cardiology Society of India, said the alarming rise in heart attacks among the youth can partly be attributed to air pollution. "Heart attacks in youth are happening 10 times more frequently than a decade ago, primarily due to air pollution. If current trends continue, India is poised to surpass China as the country most affected by air pollution-related health issues," he said.