Global smog season: How winter worsens air pollution worldwide

With the arrival of the winter season, a sharp decline in air quality has been observed worldwide.

While air pollution remains a year-round challenge, the experts warn that a combination of seasonal science and human behaviour makes it worse in the colder months, posing an adverse threat to public health.

The researchers attribute the intensification of air pollution during colder months to a phenomenon known as “thermal invasion.”

This occurs when a layer of warm air traps colder air like a lid due to which pollutant-filled air stays at ground level.

With increased emissions from heating and idling vehicles, this creates a toxic blanket over urban areas.

An environmental scientist stated, “The same pollutants are there but winter weather acts like a cap, concentrating them where we breathe. It turns our cities into a confined chamber of poor air quality.”

What causes adverse air pollution in winters?

As described in the study titled "The Impact of Seasonality on Air Quality in Terms of Pollution with Substances Hazardous to the Environment" published in MDPI, cold air possesses less moisture as compared to warm air.

This minimizes the amount of rain and snow, which is a natural way of cleaning the atmosphere. Additionally, the absence of powerful winter winds has the effect that the polluted air lingers over urban areas.

Harmful substances or pollutants present in the atmosphere are the cause of air pollution. Global organizations as World Health Organisation (WHO) and U.S. Environmental Protection Agency (EPA) tracked the major air pollutants:

• Particulate Matter (PM): Microscopic solid and liquid particles (PM 2.5) from fuel combustion, traffic, and industrial processes. This is one of the most harmful pollutants.

• Nitrogen Dioxide (NO2) & Sulfur Dioxide (SO2): Gases primarily released from vehicle exhaust and the burning of fossil fuels.
• Carbon Monoxide (CO): A colorless, odorless gas from incomplete combustion.
• Ground-level Ozone (O3): A major component of smog, formed by chemical reactions in the presence of sunlight.

The pollution effects of the pollutants are very devastating. In 2019, WHO estimated 4.2 million premature deaths in the world due to the ambient (outdoor) air, which led to strokes, heart diseases, chronic respiratory diseases, lung cancer, and acute respiratory disorders.

How to protect yourself from smog and air pollution?

In order to avoid smog and air pollution in general, there are steps that people can take in order to reduce the exposure of the person, not to mention the contribution of air pollution.

• When there is a high Air Quality Index (AQI), the optimal solution is to stay indoors and restrict outdoor activity particularly when you have respiratory or heart problems.
• Wear an appropriately fitted N95 or P100 respirator mask in case of going outside because it is a mask that is designed to filter out the particulate matter as compared to the regular surgical mask.
• During the time of staying at home, make sure that the heating, ventilation and air conditioning (HVAC) system in your house has a high-quality filter (MERV 13 or higher).
• Buy a good quality air purifier with a HEPA filter to remove PM 2.5 of the indoor air.
• Avoid indoor smoking, candle, and incense burning, gas stove, and insufficient exhaust fan use, and high Volatile Organic Compounds (VOC) products.
• Drink plenty of water to stay hydrated to ensure you airways are kept moist.
• Consume foods high in antioxidants and Omega-3 fatty acids (such as fruits, vegetables, nuts, and fish) to assist your body to combat the oxidative stress of the pollutants.

As winter deepens, understanding the seasonal dynamics of air pollution is the first step towards mitigation.

Although long-term positive results can only be achieved through shifting to sustainable solutions, a combination of informed personal choices and strict policy implementation can help to address this global issue effectively.