Cardiovascular health and air pollution during winters

Dr. Pranab Jyoti Bhattacharyya

Pranab Bhatta Pic — Prof. (Dr.) Pranab Jyoti Bhattacharyya

Vehicular traffic, crop stubble burning (especially in North India), and municipal solid waste burning are identified as the major sources of winter air pollution in India.

Bursting of crackers during Diwali, the festival of lights, also contribute to a spike in air pollution levels for a brief period of 3 to 4 days per year.

Household air pollution including cooking with wooden stove and cigarette and bidi smoking – a danger to both the smoker and those nearby (second hand or passive smoker) do add to ambient air pollution.

Cardiovascular health and air pollution during winters — Image: Powershift

In Delhi by the end of October, when the rains have ceased, the winds begin to blow in from the northwest, carrying fumes from burning fields of the farmers in the neighboring states of Punjab and Haryana who burn the stubble from the previous harvest to prepare land for the next sowing season, and the smoke is carried to Delhi contributing to the smog.

Then there is Diwali, where millions burst fire crackers to celebrate. Both events synergistically contribute to the winter air pollution during this time. Air pollution is worse in the winter months (October—January) as particles remain suspended in the air for longer duration of time due to the lower temperature, wind speed as well as higher relative humidity.

The tradition of bursting crackers during Diwali is often seen as a joyous activity. However, the harmful effects of crackers on both human health and the environment need to be appreciated. The pollution caused by crackers is multidimensional and may include air pollution, noise pollution, and even soil and water contamination.

Air pollution from crackers is particularly concerning due to the release of fine Particulate Matter (PM2.5 and PM10), which can penetrate deep into the lungs and bloodstream, causing severe health issues.

Noise pollution from crackers can lead to hearing loss and can disturb both humans and animals, leading to changes in behavior, stress, and even death in some cases.

The environmental impact of crackers is profound. The release of greenhouse gasses like carbon dioxide contributes to global warming and climate change. The heavy metals and toxic chemicals released can settle on plants, affecting their growth and contaminating the food chain. Additionally, the remnants of crackers can contaminate soil and water bodies, affecting plant and animal life.

Crackers are made using a variety of chemicals that contribute to their explosive properties and vibrant colors. Some of the common chemicals used include:

Potassium Nitrate: acts as an oxidizer and produces oxygen to sustain the combustion of the cracker,

Sulfur: helps in the ignition and burning process,

Charcoal: serves as a fuel source,

Aluminum: used to create bright flashes and sparks,

Barium Nitrate: produces green colors,

Strontium Nitrate: creates red colors,

Copper Compounds: generate blue hues.

These chemicals, when burned, release toxic fumes that contribute to air pollution and pose serious health risks.

Green crackers developed by the Council for Scientific and Industrial Research (CSIR), emits pollutants at a 30% lesser rate than their conventional counterparts. These are made using less polluting raw materials.

Their chemical formulation ensures reduced particle emission into the atmosphere by suppressing the dust produced. While regular crackers emit about 160 decibels of sound, green crackers’ emission rate is limited to 110-125 decibels. Highly pollutant substances like potassium nitrate or barium nitrate are avoided in their production.

There are three types of green crackers available in India – SWAS (Safe Water Releasers), STAR (Safe Thermite Crackers) and SAFAL (Safe Minimal Alluminium). Despite the reduced release of harmful substances, the bursting of green crackers also constitutes to air and noise pollution.

Growing medical evidence links air pollution and heart disease. Whether one live in a city where smog forecasts are routine or in a less populated place, tiny pollution particles in the air can lead to serious cardiac problems. Winter months see some of the worst air pollution levels in Delhi. In Assam, recent report suggests Guwahati, Nalbari and Nowgaon as the cities with worst air quality.

Short-term exposure to air pollution can increase the risk of heart attack, stroke, abnormal heart rhythm (arrhythmia) and heart failure in susceptible people, such as the elderly or those with preexisting medical conditions.

Patients who have undergone angioplasty and cardiac stent implantation earlier, those with coronary artery bypass graft surgery, patients with coronary blocks currently symptomatic on exertion despite being on medication, those with uncontrolled blood pressure, diabetes and blood cholesterol levels, obese persons with sedentary lifestyles, bidi and cigarette smokers, chewing tobacco users, those with chronic kidney disease are particularly vulnerable to the cardiovascular effects of environmental pollution.

The risk of death is greater from long-term exposure. Current scientific evidence suggests air pollution contributes to the development and progression of atherosclerosis, plaque that builds up in the artery walls and causes heart disease (coronary artery disease). Pollution also may play a role in high blood pressure and diabetes.

Acute and chronic exposure to Particulate Matter (PM_2.5) may even cause venous thromboembolism. This is a condition when a blood clot blocks the flow of blood through the veins. The clot can be stuck in the deep veins of the legs or arms (deep vein thrombosis) or a break away portion of the clot can travel through the veins to the lungs (causing pulmonary embolism). Pulmonary embolism can be life threatening.

The mechanisms mediating cardiovascular disease in response to air pollution are complex and may be viewed as cascading responses beginning with pollutant inhalation in the lung that results in initiating responses; recognition and transmission of these responses; and finally end-organ effector mechanisms responsible for causing cardiovascular and metabolic diseases within the human body.

Effective societal and personal strategies may help to reduce cardiovascular effects of air pollution. Urban strategies including land use, green belts, separation of pollution sources (industrial factories, roads), and planned residential communities that emphasize healthy living can avert not only air pollution but other concomitant exposures as well.

Use of personal-level low cost protective measures against PM _2.5 exposure seem to be logical. Personal measures include avoiding commuting in traffic, use of car air conditioning, and closing windows while commuting in an automobile. Improvements in home and building designs that include home ventilation and air conditioning with appropriate air filters can help avert exposures while indoors.

Face masks (cloth masks, surgical, N95) are cheap and widely available and have obtained widespread societal acceptance in the context of COVID-19 exposure. Cloth masks have the least filtration efficiency for PM_2.5, whereas N95 masks have the highest efficacy.

N95 masks worn over periods of hours to days have demonstrated significant reduction in blood pressure and improvement in other markers of cardio metabolic risk. Portable air cleaners are practical and inexpensive in-home strategies suited for at-risk populations and can effectively reduce PM_2.5 exposures by as much as 30% to 60%.

At present very little is known about the causal impact of Diwali on winter air quality. The question of how much does air pollution increase because of firecracker burning is an important one, because measures such as the ban on the sale of firecrackers impose significant costs in the form of reduced livelihoods of vast numbers of people involved in the trade.

Future research also needs to address the contribution of vehicular pollution relative to firecrackers at the same time. Although the ultimate solution to avert air pollution exposure is its elimination. A shift to zero emissions by 2045 with near 90% elimination by 2035, a minimal requirement for averting catastrophic climate changes, should help improve air quality in the near term and produce large public health effects.

Cardiovascular health — Image: Powershift

Prof. (Dr.) Pranab Jyoti Bhattacharyya, Professor of Cardiology, Cardiothoracic and Neuroscience Centre, Gauhati Medical College & Hospital, Guwahati, Assam (India) -781032 , Ph. 9435555572, E-mail: drpranabguwahati@gmail.com

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