Outdoor PM_2.5 pollution levels and their degree of compliance with WHO air quality guidelines across 760 cities in China, India, and Pakistan

Particulate matter (PM_2.5) has long been recognized as a lethal air pollutant. Multifarious anthropogenic activities, especially in the urbanized belts, lead to this pollution, and the humans and other life forms thriving in these regions suffer the worst. In this regard, the present study collated the PM_2.5 data for seven years (2017–2023) across 760 cities, encompassing three neighbouring countries, China, India, and Pakistan, that comprise more than 38% of the global population in the present date. Analyzing this comprehensive dataset, it could be inferred that 100% of the three countries’ cities exhibit PM_2.5 > 5 µg/m³, the WHO-prescribed standard limit. The PM_2.5 load in Pakistani and Indian cities was more than double that observed in Chinese cities. However, this study also noted a lack of an adequate number of monitoring stations in Pakistan compared to those in China and India. The national capital region of Delhi (India) was the worst polluted region (97.5 µg/m³) out of 63 states/provinces of these three nations. The developed belt in the Indo-Gangetic plain of India, the north-central parts of Pakistan, and the central-east regions of China showed the highest concentrations of PM_2.5. The present situation warrants immediate intervention from government levels to reduce the PM_2.5 levels, given the rate of urbanization witnessed throughout these three countries. Prolonged exposure to such high PM_2.5 levels could harm humans and these regions’ overall ecological health. Real-time PM_2.5 concentrations in all the major and minor metropolises, cities, and townships should be seriously monitored by the respective countries to prioritize research and propose effective solutions.