Delhi Air Pollution: Is There A 'Safer' Time To Step Outdoors? Here's What You Should Know

Delhi-NCR's air quality continues to be a cause of concern with pollution levels fluctuating through the day. On Wednesday (November 11), Delhi's AQI was around 300 in the morning, putting it in the 'very poor' category. But several other monitoring stations recorded even higher readings. At 12 PM, some stations were reporting AQI levels above 350, including 406 at Delhi Technological University and 380 at Burari Crossing.

Air pollution does not remain constant throughout the day. Weather conditions, wind speed, temperature, traffic, sunlight and the height at which pollutants are trapped can all impact AQI levels. Recent AQI data has also shown how pollution can change between night, early morning and daytime hours. In Delhi, pollution increased after sunset and in the early hours following Diwali, while levels fell later in the morning.

This raises an important question for people who need to commute, exercise or run errands outdoors, is there actually a safer time to step outside when the AQI is high?

Is There A "Safer" Time To Step Outdoors?

There is no universally safe time of day to go outdoors when the AQI is very poor or severe. However, pollution levels can be relatively lower during certain hours of the day depending on the weather and other conditions. For people who have the option, late morning to afternoon may sometimes be a better option than early morning or late evening.

However, this does not mean that afternoon outdoor activity is automatically safe. On November 11, several Delhi monitoring stations continued to report 'very poor' air even around noon, with some showing AQI in the severe category. This shows why checking the live AQI for your area is more useful.

Early Morning May Not Always Be Better

Many people prefer early-morning walks or outdoor exercise because the weather is cooler and roads may be quieter. However, during winter and post-Diwali pollution episodes, early morning can coincide with stagnant air and poor dispersion.

When wind speeds are low, pollutants can stay suspended close to the ground. Temperature and atmospheric conditions can also prevent pollutants from dispersing quickly. This is one reason why an early morning walk may expose you to high concentrations of particulate matter even when the weather feels pleasant. So, if the AQI is already very poor, it is better to stay indoors.

Evenings Can Also Be Risky

Evening is another period when people often step out for walks, shopping or exercise. But pollution can increase after sunset, especially due to traffic emissions. Recent data shows how pollution increases after sunset, with high levels recorded overnight before falling later in the day. This does not mean every evening will have worse air than every afternoon as conditions can change from day to day.

Instead of relying on a fixed "safe" hour, check the AQI before leaving home. Pollution can vary significantly between different parts of Delhi-NCR. For example, the current readings from Delhi stations have ranged from the poor category to very poor and severe. This shows that two people living in different parts of the city can have different exposure levels at the same time.

Tips To Follow When You're Going Out

• Wear a well-fitting mask: When pollution is high, a properly fitted N95 or equivalent respirator can reduce exposure to fine particles.
• Avoid outdoor exercise during very poor AQI: Exercise increases breathing rate, which means you inhale more air and more pollutants. Move your workouts indoors when pollution levels are high.
• Choose less busy routes: If you have to walk or cycle, avoid roads with heavy traffic and areas with smoke or dust. Vehicle exhaust and road dust can add to your exposure.
• Make your outdoor trips short: When the AQI is very poor, reduce unnecessary time outdoors, particularly if you are a child, older adult or have asthma, heart disease or other respiratory problems.
• Keep checking the AQI: Do not assume that yesterday's better air means today will be similar. AQI can change over several hours.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.