AQI:Air Quality Index and Pollution:

This comprehensive article explores the global and national dimensions of AQI -Air Quality Index, a critical indicator of air pollution and public health. Focusing on countries like the USA, Japan, China, and India, it highlights the contrasting air quality trends across the world. The article delves into the National Air Quality Index (India) and provides detailed AQI statistics for Greater Noida, emphasizing the urgent need for action. 10 most polluted cities exists world wide or globally.

What is AQI -Air Quality Index ? AQI Full Form and Meaning “

AQI stands for Air Quality Index. It is a standardized metric used globally to communicate the level of air pollution in a specific area. The AQI measures pollutants like PM2.5, PM10, Ozone (O₃), Nitrogen Dioxide (NO₂), Sulfur Dioxide (SO₂), and Carbon Monoxide (CO). AQU indexing  ranges from 0 to 500 and with higher values indicates the  worse air quality , which can leads ill health concerns.​

AQI -Air Quality Index Categories:

• Good or Normal Range : 0 – 50: Satisfactory AQI
• Moderate Range : 51 to 100 : Moderate health challenges -small number of people may affected.
• Unhealthy for Sensitive Groups Range : 101 to 150 . Health effects may be identified in  sensitive people.   if AQI range between 101 to 150.
• Unhealthy Range : 151 to 200 . Everyone may  experience the health challenges or  health effects if AQI range between 151 to 200.
• Very Unhealthy Range : 201 to 300 . Its Health alert; Maximum people  may experience serious health challenges or health  effects at maximum level if AQI range between 201 to 300.
• Hazardous Range : 301 to 500 . Emergency health conditions  if AQI range between 301 to 500.

 aqi Air Quality Overview: USA, Japan, China, India and United States

In 2025, almost 156 million people in the United States—that’s about 46% of the entire population—are breathing air that’s considered unhealthy due to high levels of ozone and fine particle pollution.

Some of the worst-affected cities of USA : According to recent data, the following cities have reported the highest AQI levels:​

1. Calipatria – AQI: 1571 :Hazardous AQI Range (USA )
2. Westmorland– AQI: 1527 : Hazardous AQI Range
3. Brawley– AQI: 1168 :Hazardous AQI Range
4. Salton City– AQI: 1141
5. North Shore of USA – AQI: 878 : Hazardous AQI Range
6. El Centro– AQI: 806 :Hazardous AQI Range
7. Mecca– AQI: 533 :Hazardous AQI Range

Japan

Japan generally maintains good air quality due to strict environmental regulations and advanced technology. However, urban areas occasionally experience moderate pollution levels, primarily due to vehicular emissions and industrial activities.​

China

China has made significant strides in improving air quality, aiming to eliminate severe air pollution by 2025. some cities still experience high pollution levels, with Kashgar recording an AQI of 294, categorized as “Severe.”

India

India continues to face severe air pollution challenges. Cities like Delhi, Ghaziabad, and Meerut frequently report AQI levels in the “Unhealthy” to “Very Unhealthy” categories. Delhi recorded an AQI of 280, indicating very unhealthy air quality. ​

2025 : World‘s Top Most Polluted Cities :

According to recent data, the following cities have reported the highest AQI levels:​

1. Calipatria – AQI: 1571 :Hazardous AQI Range (USA )
2. Westmorland– AQI: 1527 (Hazardous AQI Range) (USA )
3. Brawley– AQI: 1168 :Hazardous AQI Range
4. Salton City– AQI: 1141
5. North Shore– AQI: 878 (Hazardous AQI Range)(USA)
6. El Centro– AQI: 806
7. Mecca– AQI: 533 (Hazardous AQI Range)(USA)
8. Kashgar – AQI: 294 (China )
9. Rohtak Haryana  – AQI: 212 (Severe AQI Range) (India )
10. New Delhi – AQI: 263 (Severe AQI Range) (India )

According to IQAir’s 2024 report, the following cities recorded the highest levels of air pollution:​

1. Greater Noida, India – AQI: 272

12. Noida, India – AQI: 262
13. Ghaziabad, India – AQI: 252
14. Baghdad, Iraq – AQI: 202
15. Cairo, Egypt – AQI: 201
16. Lahore, Pakistan – AQI: 200
17. Hanoi, Vietnam – AQI: 198
18. Dhaka, Bangladesh – AQI: 195
19. Kabul, Afghanistan – AQI: 190 ​

National aqi Air Quality Index (NAQI) – India

India’s National Air Quality Index (NAQI) provides real-time data on air quality across various cities. The AQI measures pollutants like PM2.5, PM10, Ozone (O₃), Nitrogen Dioxide (NO₂), Sulfur Dioxide (SO₂), and Carbon Monoxide (CO). The Central Pollution Control Board (CPCB) publishes daily AQI bulletins to inform the public.​

aqi Air Quality Index in Greater Noida

As of April 25, 2025, Greater Noida recorded an AQI of 210, categorized as “Poor.” The primary pollutant was PM10. ​

Real-time data indicates that the AQI in Greater Noida remains in the “Unhealthy” category, with PM2.5 levels at 62.5 µg/m³. ​

Strategies & Suggestions for Betterment of AQI –Air Quality Index

1. Improving AQI is not just the responsibility of governments—every individual and community has a role to play. With increasing air pollution levels across cities and even rural regions, it’s crucial to adopt sustainable practices that positively impact the Air Quality Index (AQI) and ensure a healthier environment for current and future generations.

Promote Clean Transportation

One of the fastest ways to improve AQI in urban areas is by reducing emissions from vehicles. Opt for public transport, electric vehicles, cycling, or walking whenever possible. Governments should invest more in green public transit systems and create infrastructure that supports eco-friendly mobility. Each private vehicle taken off the road directly improves the local AQI.

Increase Urban Green Spaces

Trees and plants naturally purify the air .  Absorb carbon dioxide and release oxygen is nature of trees and plants. Planting more trees in urban and industrial zones. Significantly lower particulate matter in the air, thereby improving the AQI. vertical green walls, and community parks  and Rooftop gardens, are great solutions in  populated cities having high density .

Strict Industrial Pollution Control

Industries are major contributors to poor AQI, especially when they release pollutants without adequate filtration. Governments must enforce stricter emission standards and require industries to install real-time air quality monitoring systems. Sustainable manufacturing practices and regular audits can go a long way in keeping the AQI within safe limits.

Stop Crop and Waste Burning

Burning of agricultural residue and garbage, especially in rural and peri-urban areas, releases high volumes of harmful gases and particulate matter, drastically lowering AQI. Awareness campaigns, alternatives like composting, and government subsidies for bio-decomposers can help farmers and citizens switch to cleaner waste disposal methods.

Control Construction Dust

Construction activities generate fine dust particles that heavily pollute the air. Ensuring proper dust management at construction sites—like covering materials, watering down surfaces, and using dust barriers—can significantly reduce airborne particles and improve the AQI around these zones.

Support Clean Energy Initiatives

Shifting from fossil fuels to renewable energy sources like solar, wind, and hydro power helps reduce emissions at the source. Government incentives for installing solar panels or switching to clean cooking fuels not only improve the environment but also support better AQI in both rural and urban areas.

Adopt Indoor Air Quality Measures

While outdoor AQI gets the most attention, indoor air can also be highly polluted. Use air purifiers, avoid smoking indoors, ensure proper ventilation, and reduce the use of synthetic cleaning products. Cleaner indoor environments contribute to overall public health, especially when outdoor AQI levels are poor.

Raise Awareness and Public Participation

The public needs to be educated on the impact of their actions on the AQI. Campaigns in schools, workplaces, and local communities about air pollution and its health risks can drive change. Apps and websites that display real-time AQI levels can empower people to take informed decisions and pressure authorities into action.

1. These practical steps, when adopted collectively by individuals, communities, corporations, and governments, can lead to a meaningful reduction in air pollution and a visible improvement in AQI. Cleaner air is not a luxury—it’s a necessity.
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Summary

The Air Quality Index (AQI) serves as a crucial indicator of air pollution levels, impacting health and the environment. Countries like the USA, Japan, China, and India face varying challenges in maintaining air quality. Urban areas, especially in India and parts of the USA, report alarming AQI levels, necessitating immediate action. Implementing sustainable practices and raising public awareness are vital steps toward improving air quality globally.

Frequently Asked Questions (FAQs)

Q1: What is AQI?

A: AQI stands for Air Quality Index, a tool used to communicate how polluted the air currently is or how polluted it is forecast to become.​Wikipedia

Q2: How is AQI measures ?

A: The AQI measures pollutants like PM2.5, PM10, Ozone (O₃), Nitrogen Dioxide (NO₂), Sulfur Dioxide (SO₂), and Carbon Monoxide (CO).

Q3: Write about high AQI effects on health  ?

A: High AQI levels can lead to respiratory issues, cardiovascular diseases, and other health problems, especially for sensitive groups like children and the elderly.​

Q4: How can any individuals can reduce their exposure in  air pollution?

A: Limit outdoor activities during high pollution days, use air purifiers indoors, and wear masks when necessary.​

References

1. Air Quality Index | American Lung Association
2. Air Quality Index
3. Greater Noida Air Quality Index (AQI) : Real-Time Air Pollution, Graph, Historical Data| AQI USA
4. The Guardian
5. Prana AirReuters
6. cpcb.nic.in+1airquality.cpcb.gov.in+1
7. aqicn.org+5AQI.in+5IQAir | First in Air Quality+5IQAir | First in Air Quality+12aqicn.org+12Wikipedia+12IQAir | First in Air Quality+10cpcb.nic.in+10NRDC+10
8. The Guardian+4Health Policy Watch+4IQAir | First in Air Quality+4
9. IQAir | First in Air QualityThe Sun

10. AirNow.gov – AQI Basics
11. AQI.in – Real-time Most Polluted City Ranking
12. CPCB – AQI Report

Bala Datt Sharma,Managing Editor,Prakriti Darshan ,International Journal of Environment Science and Multidisciplinary Studies ,Nature & Environment Magazine

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