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Friday, June 05, 2020

Amid coronavirus lockdown, world’s top 5 polluted cities breathe clean air

With lockdown in place, here's how the world's top five polluted cities fare in air quality index

By: Express Web Desk | New Delhi | Updated: April 8, 2020 9:31:08 pm
coronavirus pollution impact, aqi delhi, aqi today, india lockdown, lockdown coronavirus, covid 19 lockdown measures Clear blue skies adorn the iconic Red fort in Delhi amid a nationwide lockdown to contain the spread the novel coronavirus (Express Photo by Amit Mehra)

With the lockdown in place to contain the spread of the novel coronavirus, cities across the world are breathing cleaner air as human activity is virtually brought to a standstill.

India especially has more reason to rejoice this silver lining. According to the 219 world ranking, India accounts for two-thirds of the world’s most polluted cities — 21 of the most polluted 30 cities; 14 of the highest 20; and six of the highest 10.

According to the Air Quality Index scale, as defined by the US-EPA 2016 standard, an AQI between 0 and 50 is considered to be “good” while between 51-100 is considered “moderate”. And between 101-150, it is considered “unhealthy for sensitive groups”. The air quality is rated “unhealthy” if AQI is between 151-200 and “very unhealthy” between 201-300. The AQI is considered to be “hazardous” if it is found above 300.

With the lockdown in place, here’s how the top five polluted cities fare now

  1. Ghaziabad, India

With an average AQI of 110.2 in the year 2019, Ghaziabad topped the list of the most polluted city in the world, its March average being 89.3.

Come 2020, the city saw a significant improvement in its air quality, as constructions were banned and people directed to stay indoors in a bid to flatten the curve of COVID-19.

According to the data from March 10 to April 8, air quality in the city improved to “moderate” on March 27. In the almost one-month period, its peak was on March 19, when the air quality dropped to 177 on the air pollution index.

Data sourced from

On March 22, when the Janata Curfew was announced, the air quality improved to 160, but it was still unhealthy. A day after a 21-day nationwide lockdown was announced on March 23, pollution levels dropped significantly, bringing the AQI to moderate for eight consecutive days, from March 27 to April 3.

However, April 5 reversed the trend, bringing the AQI to 158 — same as the pre-lockdown days–with many bursting crackers at 9 pm when Prime Minister Narendra Modi asked people to turn lights off and light diyas and candles to unite in the challenge to “fight the darkness of coronavirus”.

It took two days until April 7 to bring back the AQI to moderate, now at 83.

2.  Hotan, China

China has been struggling for years to enforce environmental rules and crackdown against polluting industries. A few cities, however, continue to be major offenders. This includes Hotan. Not far behind Ghaziabad, Hotan had an average AQI at 110.1 in the year 2019, becoming the second most polluted city in the world.

With China being the first nation to be hit by the novel coronavirus, and the first to subsequently enforce stringent lockdown measures, the city did see an improvement in its air quality, which, however, continued to remain unhealthy.

Data sourced from

As per data between March 10 and April 8, Hotan witnessed the peak on March 11 with the AQI crossing 1700. While the air quality did improve, the AQI remained between 152 and 273 from March 14 to 25.

3. Gujranwala, Pakistan

With Pakistan reporting over 4,000 cases of coronavirus, including 60 deaths, the country hasn’t yet enforced a complete lockdown. The country, however, was making frantic efforts to tackle the pandemic and Prime Minister Imran Khan once again warned the people to follow official guidelines on self-isolation or the virus would spread further.

Gujranwala is a district in Pakistan’s Punjab province, which has recorded the most number of coronavirus cases in the country at over 2,000. The district is also notorious for its high pollution levels. Both Gujranwala and Faisalabad, which rank third and fourth, respectively, in the 2019 index, experience annual average PM2.5 levels that are more than 10 times the WHO target for annual PM2.5 exposure.

Data sourced from

While the city’s 2019 average AQI was 105.3, data for March this year shows an incremental improvement in its air quality.

From March 10, the city has recorded air quality at moderate or good, barring seven days when it remained unhealthy. From March 24, the air quality has remained consistently moderate, as the country goes into lockdown, with only essential services allowed to operate.

4. Faisalabad, Pakistan

With an AQI of 72 Wednesday, Faisalabad in Pakistan is witnessing an improvement in its air quality, which remained favourable since March 24. In 2019, the city’s average AQI was at 104.6.

Data sourced from

With the country, as the rest of the world, stays in lockdown and self-isolation to contain the spread of the Covid 19, Faisalabad has reported a substantial improvement in its air quality, since Paksitan reported its first casualty on  March 18.

5. Delhi, India 

With industries, private vehicles and public transport shut during the lockdown, air in Delhi and NCR, among the worst in the country, was the least polluted in March since air quality records have been maintained. Delhi had an average AQI of 98.6 in 2019, making it the fifth most polluted city in the world that year.

The capital’s air quality plunged Sunday evening, after several residents went a step ahead in heeding Prime Minister Narendra Modi’s call to light diyas by setting off firecrackers. Data from six monitoring stations of the Delhi Pollution Control Committee showed concentration of PM 2.5 and PM 10 spiked suddenly after 9pm, when firecrackers were set off. A Delhi environment department official said, “The spike was due to firecrackers, as currently there is no other source of emission.”

Here’s a quick Coronavirus guide from Express Explained to keep you updated: What can cause a COVID-19 patient to relapse after recovery? | COVID-19 lockdown has cleaned up the air, but this may not be good news. Here’s why | Can alternative medicine work against the coronavirus? | A five-minute test for COVID-19 has been readied, India may get it too | How India is building up defence during lockdown | Why only a fraction of those with coronavirus suffer acutely | How do healthcare workers protect themselves from getting infected? | What does it take to set up isolation wards?

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