A groundbreaking district-level analysis has exposed a critical and often overlooked driver of toxic air in Haryana. The study reveals that secondary pollutants, specifically ammonium sulfate, constitute nearly one-third of the deadly PM2.5 particulate matter across most of the state, including the bustling National Capital Region (NCR) districts.
District-Level Data Paints a Stark Picture
The research, conducted by the Centre for Research on Energy and Clean Air (CREA), provides granular data on this invisible threat. It found that concentrations of ammonium sulfate range from 12 to 20 micrograms per cubic meter (µg/m³), accounting for a significant 29% to 34% of the total PM2.5 mass in various districts.
Faridabad emerged as the most impacted area, where ammonium sulfate contributes a staggering 34% to PM2.5 levels at an average concentration of 20 µg/m³. The situation is equally severe in Gurgaon, Sonipat, and Palwal, where this secondary component makes up 33% each, with concentrations hovering around 19 µg/m³. High levels were also recorded in Rohtak and Jhajjar, with a 32% contribution.
A Structural, Not Marginal, Problem
These findings confirm earlier state-level research indicating that secondary pollution—formed in the atmosphere from precursor gases—is a structural pillar of Haryana's annual PM2.5 burden. Notably, even districts with relatively lower overall pollution are not spared.
For instance, Panchkula and Yamunanagar report average ammonium sulfate concentrations of 12 µg/m³, which still makes up 30% of their PM2.5. The share is 31% in Ambala and 29% in Sirsa. A consistent pattern is visible across central and western Haryana, including Hisar, Fatehabad, Karnal, and Nuh, where contributions remain between 31% and 32%.
"What the district-level data from Haryana shows clearly is that secondary pollution, especially ammonium sulfate, is not a marginal or seasonal issue but a structural driver of PM2.5," stated Manoj Kumar, an India analyst at CREA.
Implications for Policy and Clean Air Programs
The data underscores a crucial flaw in current air quality management strategies. Fine particle pollution in Haryana is not solely a product of local dust, traffic, or construction. A major portion is secondary PM2.5, formed from chemical reactions involving sulfur dioxide (SO2), nitrogen oxides, and ammonia in the atmosphere.
This revelation coincides with the Centre's consideration of revisions to the National Clean Air Programme (NCAP). Experts have long criticized NCAP's predominant focus on PM10 and visible dust, arguing it fails to address cross-boundary secondary PM2.5. India remains the world's largest emitter of sulfur dioxide, primarily from coal-fired power plants.
CREA has issued a stern warning: unless emissions of SO2 and other precursor gases are stringently controlled—including through strict enforcement of power plant norms—PM2.5 levels in Haryana and the wider NCR are unlikely to see sustained improvement, even if local dust management measures are enhanced.
