Mercury Air Pollution in Delhi: What You’re Inhaling Without Knowing

Air pollution in Delhi is something we’re all painfully familiar with as smog, dust, and hazardous gases like nitrogen oxides and carbon monoxide. These seem to dominate every discussion about the city’s environment. But recent findings show that the danger doesn’t stop there. Mercury air pollution in Delhi is now emerging as a new, invisible threat that could be affecting your health every day.

Yes, mercury, a toxic heavy metal most of us associate with thermometers or industrial waste, is now in the air we breathe. It’s not just ordinary particles or smog anymore; it’s a metal contaminant silently invading our lungs. The alarming question is: where is this mercury in the air coming from? And how much of it are we breathing in without even realising it?

Recent research has revealed that Delhi is not only battling particulate pollution. It is also one of the hotspots for mercury air pollution in India. From coal-burning power plants and industrial emissions to daily traffic fumes, mercury is released into the atmosphere and lingers far longer than most pollutants. This blog delves into the study, examining what mercury is, its origins, its dangers, and its implications for the health of Delhi’s residents.

If you live, work, or raise a family in Delhi, understanding this invisible threat is not just important because it could change the way you think about the air you breathe every single day.

What Is Mercury and Its Sources?

Mercury (Hg) is a toxic heavy metal that exists in several forms. It includes elemental mercury (Hg₀), inorganic mercury compounds, and organic mercury compounds. Elemental mercury is a silvery-white liquid metal at room temperature. And it is commonly found in thermometers, fluorescent lights, and some electrical switches. When released into the atmosphere, mercury can travel long distances before settling onto land or water bodies, where it can enter the food chain.

The primary sources of mercury emissions include:

• Coal Combustion: Burning coal for electricity and heat is a significant source of mercury emissions.
• Industrial Processes: Certain industrial activities, such as cement production and metal processing, can release mercury.
• Vehicular Emissions: Automobiles, especially those using fossil fuels, emit mercury through exhaust gases.
• Waste Incineration: Burning waste materials can release mercury into the atmosphere.

Mercury Levels in Delhi: A Growing Concern

The study, spanning from 2018 to 2024, revealed that Delhi’s air contains the highest mercury concentration among the three Indian cities studied, significantly exceeding global background levels. Daily average gaseous elemental mercury (GEM) concentrations were highest in Delhi (6.9 ± 4.2 ng/m³), followed by Ahmedabad (2.1 ± 0.7 ng/m³) and Pune (1.5 ± 0.4 ng/m³). The elevated mercury levels in Delhi were consistent with conditions of atmospheric stability and shallow boundary layer height, indicating a significant local emission source.

The study attributed 72% to 92% of mercury emissions to human activities, primarily from the combustion of fossil fuels, industrial activities, and vehicular emissions. Natural contributions were estimated to account for 8% to 28% of the mercury levels. Annual GEM emissions in Delhi were estimated at 1.6–90.5 kg/year, with a 32% reduction over the study period, indicating the potential effectiveness of emission control measures.

Is Mercury Air Pollution in Delhi Really Dangerous?

Yes, mercury pollution poses significant health risks. While the study indicated that the hazard quotient (HQ) for chronic exposure to mercury in Delhi remained below World Health Organisation (WHO) thresholds, the elevated levels still present a cause for concern. Mercury exposure can lead to various health issues, including:

• Neurological Effects: Mercury can damage the nervous system, leading to symptoms such as tremors, memory loss, and mood swings.
• Kidney Damage: Inorganic mercury exposure may result in damage to the kidneys.
• Respiratory Issues: Inhalation of mercury vapours can cause respiratory problems.
• Skin and Eye Irritation: Direct contact with mercury can lead to skin rashes and eye irritation.

These health effects underscore the importance of addressing mercury pollution in urban environments.

Comparative Analysis of Mercury Air Pollution: Delhi, Ahmedabad, and Pune

A recent study published in the journal Air Quality, Atmosphere & Health has uncovered alarming findings about mercury air pollution in Delhi. The study also monitored mercury levels in Ahmedabad and Pune. While Delhi recorded the highest mercury concentrations, both Ahmedabad and Pune showed significant levels as well, highlighting the widespread nature of mercury pollution across Indian cities. The correlation between GEM and carbon monoxide (CO) suggests that combustion-related urban emissions, particularly from coal and industrial sources, are key contributors to mercury pollution in these cities.

How Exposure to Mercury Air Pollution in Delhi Can Harm Your Health?

Here are the health issues related to short-term exposure to high mercury levels:

• Acute Respiratory Distress: You can face sudden respiratory issues, such as breathing difficulty, chest tightness, cold/cough, etc. 
• Neurological Symptoms: Short-term exposure may also result in symptoms such as headaches, dizziness, and mood swings.

Long-term exposure can lead to:

• Chronic Neurological Disorders: Long-term mercury exposure can result in permanent nervous system damage. This nervous system damage can lead to motor dysfunction or cognitive deficits. 
• Kidney Damage: Long-term exposure can result in chronic kidney disease, such as kidney failures, severe infections or other issues. 
• Developmental Impacts: In pregnant women, mercury exposure can adversely affect fetal development, leading to developmental delays and cognitive impairments in children.

These health risks emphasise the need for stringent air quality monitoring and pollution control measures.

Conclusion

The recent study highlights a critical aspect of Delhi’s air quality that has often been overlooked: mercury pollution. While efforts have been made to control particulate matter and vehicular emissions, addressing mercury pollution requires targeted strategies, including:

• Enhanced Monitoring: Implementing comprehensive monitoring systems to track mercury levels across urban areas.
• Emission Control Technologies: Adopting cleaner technologies in industries and power plants to reduce mercury emissions.
• Public Awareness Campaigns: Educating the public about the sources and health risks of mercury pollution.

By taking proactive measures, Delhi can mitigate the health risks associated with mercury pollution and improve the overall air quality for its residents.