This dataset contains historical air quality measurements from three major urban areas: Madrid, Spain and Cali, Colombia, obtained from api.aqi.in, and London, United Kingdom, obtained from londonair.org.uk. The data were collected from 15 fixed monitoring stations in Madrid, 18 in Cali, and 40 in London, offering a comprehensive view of air pollution levels in each city over time. The pollutants and their corresponding measurement units are as follows: Pollutant Unit Ozone (O3) parts per billion Nitrogen dioxide (NO2) parts per billion Fine particulate matter (PM2.5) microgram per cubic meter Particulate matter (PM10) microgram per cubic meter Carbon monoxide (CO) parts per billion Sulfur dioxide (SO2) parts per billion Additionally, it contains the following meteorological data: Variable Unit Temperature degrees Celsius Dew point degrees Celsius Relative humidity percentage Finally, each measurement contains a topic value that serves to uniquely identify the monitoring station that produced it, the timestamp, and the GPS coordinates of the monitoring station. Data are divided into yearly CSV for the user's convenience. Data Collection and Processing for Madrid and Cali: Data were retrieved via the endpoint: https://api.aqi.in/api/v1/getMonitorsByCity, with the corresponding city specified in the request header. Records were collected at 5-minute intervals and stored in a MongoDB database in JSON format whenever new data became available. Non-essential fields (e.g., units, location name) were removed. Sensor topics were simplified by retaining only the final four digits of the topic tag. In Cali, 39 sensors that appeared only once were excluded to ensure data reliability. Data Collection and Processing for London: Data were downloaded from the API https://londonair.org.uk/london/asp/datadownload.asp, with the corresponding monitoring station as part of the URL and the period set as hourly. Data from all stations and pollutants were combined into a single CSV file. GPS coordinates for all stations were downloaded from https://londonair.org.uk/london/asp/publicdetails.asp and attached to the CSV file. Stations separated by less than one meter are combined into a single monitoring station. Dew point is calculated and added to the CSV. Source of Data: This dataset contains air quality data originally retrieved via the api.aqi.in platform and londonair.org.uk. The data is sourced from public air quality monitoring stations operated by: Alcaldía de Santiago de Cali for data related to Cali, Colombia (https://www.cali.gov.co/dagma/publicaciones/38365/sistema-de-vigilancia-de-calidad-del-aire-de-cali-svcac/) Ayuntamiento de Madrid for data related to Madrid, Spain (https://airedemadrid.madrid.es/portal/site/calidadaire) Imperial College London for data related to London, United Kingdom (https://londonair.org.uk/london/asp/datadownload.asp) Rights and Usage: The original data is made available through public monitoring systems by the respective municipal governments listed above. The data was accessed via api.aqi.in, which aggregates publicly available air quality information. This dataset is shared for academic and research purposes only, and to the best of our knowledge, the underlying data is in the public domain. Funding: This work was supported by the grant PID2023-148214OB-C21 funded by MICIU/AEI/10.13039/501100011033 and by FEDER/EU. This work was also supported in part by the grant PDC2025-165710-C22 funded by MCIN/AEI/10.13039/501100011033. This work was also supported by the grant PCI2024-153485 funded by MICIU/AEI/10.13039/501100011033 and by the European Union. This research was also funded by the PRIMA Programme under Grant Agreement No. 2431 (FUSION: Comprehensive and sustainable solution to minimize food loss and waste and promote food security in the Mediterranean region). The work of Francisco-Jose Alvarado-Alcon was supported by the Spain’s Ministry of Universities under Grant FPU22/00316.