Every year, as the temperature drops and the winds calm, the familiar chill in the air can be felt, followed by something less welcoming. A thick, greyish haze fills the air, often known as smog. Smog is a type of air pollution that is a mixture of fog and smoke, which creates a heavy, toxic haze in the air. Many factors can contribute to the formation of smog, such as the burning of fossil fuels, industrial pollution, vehicle emissions, weather, and geographic conditions. You may have also heard that there is a rise in the Air Quality Index (AQI) due to smog during this season. But is it a health emergency that can affect our lungs?
In December 2024, according to data collected from the Central Pollution Control Board (CPCB), there were significant fluctuations in AQI levels during winter. For instance, in Delhi and the NCR regions, the air quality index value was reported as worse than any year in 2024, which was far above the safe limit of 100. [1]
However, you can’t change the air quality overnight, but for sure can protect your lungs and reduce their exposure. Now let’s just dive in to know how smog affects your body in winter and what steps you can take to stay safe.
What Is AQI?
The Air Quality Index (AQI) is the simplest way to measure the air pollution levels. It is a colour-coded system that can help evaluate the health risks and effects. Different colours mean different air quality levels:
- 0-50: The colour is green, and it is considered good air quality.
- 51-100: The colour is often represented as yellow, and the air quality is moderate.
- 101-150: It is considered unhealthy for sensitive groups, and the colour is often orange.
- 151-200: It’s represented by the red colour, and the air quality is considered unhealthy and very poor.
- 201-300: Air quality is severe and highly unhealthy, and it is represented by the purple colour. Even healthy people can experience symptoms.
- 301-500: Hazardous level of air quality, and the colour is maroon.
Why Does Air Quality Worsen in Winter?
Have you ever wondered why pollution is worse in winter? During colder months, a temperature inversion occurs where warm air traps colder air (along with pollutants) close to the ground, preventing them from dispersing. Combined with this, when lower wind speeds and higher emissions from vehicles and heating sources occur, it can create a dense layer of smog that hangs over cities, along with the air around. Burning fossil fuels or agricultural residues can also add to this pollution load and push the AQI levels even higher, making the situation even worse.
Impacts of Smog On Health
Breathing in polluted air does not just irritate your lungs – it can affect your entire body. While the effects of smog (air pollution) are not just visible in the grey sky. For many, it can be coughing, burning eyes, or heaviness in the chest. For others, especially children, the elderly, and those with any ongoing illness (like asthma or chronic obstructive pulmonary disease), it can be more severe. Lungs, being the vital organ, need much protection from this fatal smog, and hence, there is an emerging urge to know the early signs for maintaining their health.
Early Signs Your Lungs May Be Struggling
It is often easy to ignore the first few signs of pollution-related effects on your body, but being aware can help you act early.
– Shortness of breath even when you are just climbing stairs
– Frequent colds or bronchitis
– Persistent cough or throat irritation
– Pain or tightness in the chest
If these symptoms persist beyond a week, there is a higher risk to your lung health. In such a case, you need to consult a medical professional to get it corrected, especially in cases of an earlier history of any other respiratory issues like asthma, etc., which can make it even worse.
7 Smart Ways to Shield Yourself from Pollution This Winter
1. Go for Eco-Friendly Transport Options
Opt for clean, sustainable, and environmentally friendly options to get around. Consider carpooling, public transport, or eco-friendly transport options (like cycling, electric vehicles, etc.) for day-to-day activities. One step from an individual can cause an initiative towards better air.
2. Invest In Air Purifiers
For those who live in high-pollution areas, an air purifier can significantly reduce indoor air pollution levels. Keep windows closed during smog-heavy mornings and evenings, but ventilate briefly in the afternoon when the air clears.
Get good and affordable air purifier options delivered at your doorstep in just a click.
3. Use Protective Masks
Not all masks are effective against pollution. Choose an N95 mask for good protection, as it can filter out fine particles (like carbon monoxide) and reduce the carbon monoxide levels of air pollution [2] that a cloth or fabric mask doesn’t offer.
4. Do Smart Exercise
Physical activity is essential for a healthy body, but be mindful of where and when. Do indoor workouts or yoga on high-AQI days. Simple breathing exercises like pranayam can also help strengthen your lungs.
5. Eat Lung-Friendly Foods
Foods rich in antioxidants and omega-3 fatty acids can help reduce oxidative stress caused by inhaled pollutants. Eating right can help enhance and support lung health.
6. Stay Hydrated
Polluted air can dry out your airways. Drinking enough water helps the body flush out toxins and keep the mucous membranes moist, which can improve respiratory defence.
7. Stay Updated On Air Quality
Start your day by checking the air quality index on your smartphone or local news. This small step can alert you and help you avoid outdoor activities when the AQI levels cross 200.
Lung-Friendly Takeaway
You may see foggy mornings and feel nostalgic, but when that haze turns into smog, it is a warning sign that we cannot ignore. India has the most polluted cities in the world, according to the World AQI Report 2025 [3], which means protecting your lungs is not just a seasonal thing – it is an everyday responsibility. So this winter, just adapt small lifestyle changes, stay alert, and make choices for better health for you and your family.
FAQs
Q. How to protect your lungs from bad air quality?
Limit outdoor activities during high air quality index days, wear an N95 mask if going out is important, use indoor air purifiers, stay hydrated, and eat good food – all these steps can support lung health.
Q. Why does the air quality index rise in winter?
Winter brings temperature inversion, low wind speeds, and increased emissions from vehicles & crop burning, trapping pollutants near the ground and thus raising the levels.
Q. What are the first signs of lung problems?
Persistent coughs, wheezing, shortness of breath, chest tightness, frequent respiratory infections, or unusual fatigue may indicate early lung problems.
Q. How to keep lungs healthy in winter?
Exercise indoors or when air quality is better, avoid smoking and indoor pollutants, eat antioxidant-rich foods, stay hydrated, and monitor the air quality index regularly.
Q. What is the difference between smog and smoke?
Smoke comes from burning materials, while smog is a mixture of smoke, fog, and air pollutants that is present in the air, especially during winter.
References
1. Central Pollution Control Board AQI Report – December 2024
https://cpcb.nic.in/uploads/AQM/AQ-NCR-31122024.pdf
2. Soeroso N, Intan T, Ichwan M, Fadlurrahman M, Ananda F. Four-type of Masks and its Effectiveness Based on Reduced Level of Expiratory Carbon-monoxide. Medical Archives. 2020;74(5):342. doi:10.5455/medarh.2020.74.342-345
3. AQI Ranking 2025: Real-time World most polluted cities. AQI.in. https://www.aqi.in/in/real-time-most-polluted-city-ranking. Published October 24, 2025.
(The article is written by Sneha Jajoo, Intern, Clinical Health & Content, and is reviewed by Dr.Subita Alagh, Assistant Team Lead, Disease Content.)