In the seven years from 2017, Noida recorded its best average AQI in 2023 and the second-best average PM10 and PM2.5 concentrations in the air, according to official data. The average Air Quality Index (AQI) for 2023 in Noida was recorded at 188. It was recorded at 199 in 2022, 208 in 2021, 189 in 2020, 218 in 2019, 229 in 2018 and 214 in 2017, according to the annual CAAQMS (Continuous Ambient Air Quality Monitoring Stations) data.

According to the Central Pollution Control Board (CPCB), an AQI between 0-50 is ‘good’, 51-100 is ‘satisfactory’, 101-200 is ‘moderate’, 201-300 is ‘poor’, 301-400 is ‘very poor’ and 401-500 is ‘severe’, with the possible impact of air quality on health increasing at every stage.

In terms of particulate matter (PM)2.5, the average for 2023 was 83, up from 79 in 2022 but down from 99 in 2021, 94 in 2020, 111 in 2019, 116 in 2018 and 163 in 2017, the data showed.

In terms of PM10, the average for 2023 was 189. The figure was 210 in 2022, 221 in 2021, 183 in 2020, 221 in 2019, 210 in 2018 and 189 in 2017, according to the data.

PM2.5 and PM10 refer to fine particulate matter in the air, with the numbers indicating their size in micrometres.

PM2.5 are fine particles with a diameter of 2.5 micrometres or less, about the width of a human hair. These are so small that these can penetrate deep into the lungs and even enter the bloodstream, posing significant health risks.

PM10 are coarser particles with a diameter of 10 micrometres or less, about the width of 10 human hairs. While not as concerning as PM2.5, these can still irritate the airways and worsen respiratory problems.