Faridkot in Punjab has emerged as the most polluted city in India, recording an Air Quality Index (AQI) of 1,009.Bathinda and Jalandhar, also in Punjab, occupy the second and third positions, with AQI readings of 739 and 695, respectively.The ranking shows that air quality has reached the hazardous category across all 10 cities on the list. Punjab and Uttar Pradesh account for four cities each, while Haryana and Jammu and Kashmir have one city each.ALSO READ: Delhi's Diwali Pollution Worst In 5 Years, AQI Stays 'Very Poor' Next MorningSirsa in Haryana ranks fourth with an AQI of 566, followed by Hoshiarpur in Punjab at 558.Aligarh and Budaun in Uttar Pradesh occupy the sixth and seventh positions, recording AQI levels of 474 and 468, respectively.Srinagar in Jammu and Kashmir ranks eighth with an AQI of 450. Lucknow follows closely at ninth with a reading of 448, while Prayagraj rounds off the top 10 with an AQI of 439.Top 10 Most Polluted Cities In India: Full ListWhich States Have The Most Cities In The Top 10?Punjab and Uttar Pradesh have the highest representation in the ranking, with four cities each.ALSO READ: Dehradun Records PM2.5 Levels Of 830 After Diwali Fireworks, Expert Warns Of Health RisksPunjab's Faridkot, Bathinda, Jalandhar and Hoshiarpur feature in the list. Uttar Pradesh is represented by Aligarh, Budaun, Lucknow and Prayagraj.Sirsa is the only city from Haryana, while Srinagar is the sole entry from Jammu and Kashmir.What Does AQI Mean?The Air Quality Index (AQI) is a measure used to communicate air pollution levels and their potential impact on health. It converts data on different air pollutants into a single number, making it easier for people to understand the quality of the air they breathe.India's Central Pollution Control Board (CPCB) classifies AQI readings into six categories: Good, Satisfactory, Moderate, Poor, Very Poor and Severe.The AQI is calculated using pollutants such as PM2.5, PM10, nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide, ammonia and lead.The categories under India's National Air Quality Index are:Good: 0-50Satisfactory: 51-100Moderate: 101-200Poor: 201-300Very Poor: 301-400Severe: 401-500What Are PM2.5 And PM10?AQI readings are based on several air pollutants including particulate matter.PM2.5 are fine particles with a diameter of 2.5 micrometres or smaller. PM10 are particles with a diameter of 10 micrometres or smaller.These particles can be inhaled into the respiratory system. PM2.5 is particularly concerning due to its size that enables it to penetrate deep into the lungs.High concentrations of particulate matter can cause breathing discomfort and it can aggravate existing respiratory and cardiovascular conditions.Who Should Be Careful?People with asthma and other respiratory conditions, children, older adults and those with heart-related illnesses are more vulnerable to the effects of air pollution.Prolonged exposure to polluted air and strenuous outdoor activity can increase the risk of health complications, particularly when air quality is in the Severe category.ALSO READ: Dehradun Records PM2.5 Levels Of 830 After Diwali Fireworks, Expert Warns Of Health RisksResidents in affected cities should monitor local air quality updates and follow appropriate precautions. Limiting prolonged outdoor activity and reducing exposure to polluted air may help minimise health risks.Air quality readings can change throughout the day depending on weather conditions, wind speed and pollution levels. The figures in this ranking reflect the readings supplied for this copy and may vary across monitoring stations and air quality platforms.