Air Pollution's Worst Offenders: A Database

The World Health Organization (WHO) maintains an air quality database that compiles ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) in over 4300 human settlements across more than 100 countries. The database, which is regularly updated, provides a comprehensive overview of air pollution levels in cities worldwide, with data collected from various sources, including official country reports and websites. This information is crucial for raising awareness, establishing baselines, and advocating for actions to address the health risks associated with air pollution, which include respiratory infections, heart disease, and cancer.

WHO's air quality database compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 or PM2.5)

The World Health Organization (WHO) has been compiling and publishing ground measurements of air quality and the annual mean concentrations of particulate matter since 2011. The WHO Ambient Air Quality Database compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 or PM2.5) which represent an average for the city or town as a whole, rather than for individual stations. The database is updated regularly every 2-3 years and currently hosts data from 7,182 human settlements in more than 120 member states.

The primary sources of data are official country reports sent to WHO upon request, official national and subnational reports, and national and subnational websites that contain measurements of PM10, PM2.5, or NO2. The data is used to derive the Sustainable Development Goal Indicator 11.6.2, Air quality in cities, for which WHO is the custodial agency. The latest version of the database (Version 2024 V6.1) was released in January 2024.

The annual mean concentration of PM2.5 is estimated using improved modelling with data integration from satellite remote sensing, population estimates, topography, and ground measurements. PM2.5 particles can penetrate deeply into the respiratory tract and constitute a risk for health by increasing mortality from respiratory infections and diseases, lung cancer, and selected cardiovascular diseases. Therefore, it is critical to have robust data on air pollution to enable public action and advocate for actions that can improve air quality.

While the database includes data from many locations around the world, there are still some areas with little or no monitoring. The amount of monitoring varies by geographical area, and additional data is needed to produce global estimates at high resolution. The measurements in the database are localized averages, and the heterogeneity of measurement methods and techniques should also be considered when interpreting the data.

The data is used to derive the Sustainable Development Goal Indicator 11.6.2 for air quality in cities

The World Health Organization (WHO) is a custodian agency for the Sustainable Development Goals (SDG) indicator 11.6.2. This indicator measures the annual mean levels of fine particulate matter (e.g. PM2.5 and PM10) in cities (population-weighted). The data compiled in the WHO Ambient Air Quality Database is used as input to derive this indicator.

The database compiles ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter of a diameter equal to or smaller than 10 μm (PM10) or equal to or smaller than 2.5 μm (PM2.5). These measurements aim to represent an average for the city or town as a whole, rather than individual stations. Both groups of pollutants originate mainly from human activities related to fossil fuel combustion.

The database is updated regularly every 2-3 years since 2011. As of 2022, it hosts data on air quality for over 4,300 human settlements in more than 100 countries. The primary sources of data are official reports of countries sent to WHO upon request, official national and subnational reports, and national and subnational websites that contain measurements of PM10 or PM2.5 and ground measurements.

The data in the database serves several purposes. Firstly, it helps establish a baseline for air pollution levels globally, allowing countries and the international community to track progress, make comparisons, and advocate for actions to improve air quality. Secondly, it contributes to health indicators monitored by the WHO, such as SDG target 3.9.1, which aims to reduce deaths and illnesses from air pollution, and SDG target 7.1.2, which focuses on ensuring access to clean energy in homes. Finally, the data is used to derive the SDG indicator 11.6.2 for air quality in cities, which specifically targets reducing the environmental impact of urban areas by improving the air people breathe.

WHO monitors the exposure levels and health impacts of air pollution at the national, regional, and global levels

Air pollution is a critical global health issue, and the World Health Organization (WHO) is at the forefront of monitoring and addressing it. WHO's Air Quality and Health Unit works across three key areas: knowledge, evidence, and measuring progress; institutional capacity building and technical support; and leadership and coordination.

At the national level, WHO supports member states by providing technical guidance, tools, and authoritative advice on health issues related to air pollution. This includes monitoring and reporting on global trends and changes in health outcomes associated with actions taken to address air pollution. WHO also encourages countries to employ a mixture of measurements and modelling methods to address local air quality issues while balancing national priorities and resource availability. For instance, the new report, "Overview of Methods to Assess Population Exposure to Ambient Air Pollution," highlights emerging methods such as machine learning and geostatistical data fusion, which can be used locally and nationally to monitor air pollutants and track progress.

Regionally, WHO has identified that low- and middle-income countries disproportionately bear the burden of outdoor air pollution, with 89% of the 4.2 million premature deaths occurring in these areas, particularly in the WHO South-East Asia and Western Pacific Regions. WHO's regional offices play a crucial role in coordinating with member states and sub-national entities to implement policies promoting air quality and health.

At the global level, WHO provides leadership and advocacy for better air quality everywhere. They release country estimates on air pollution exposure and health impacts, with the latest model including data from over 3000 locations. WHO also serves as a custodian agency for the Sustainable Development Goals (SDG), specifically targeting the reduction of adverse per capita environmental impacts of cities by 2030. Additionally, WHO has developed the Data Integration Model for Air Quality (DIMAQ), which provides accurate global estimates of air pollution exposure. Furthermore, WHO launched BreatheLife, a global communications campaign to raise awareness about air pollution's health and climate risks.

WHO's database includes data from over 4300 human settlements in more than 100 countries

The World Health Organization (WHO) is committed to monitoring air pollution and its health impacts at the national, regional, and global levels. To this end, the organization has developed the WHO Ambient Air Quality Database, which compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5). The database aims to represent the average air quality for entire cities or towns, rather than individual stations.

The WHO air quality database is a valuable resource, currently encompassing data from over 4300 human settlements in more than 100 countries worldwide. It is regularly updated, ensuring that the information remains current and relevant. The data is primarily sourced from official country reports submitted to WHO upon request, as well as national and subnational reports and websites that include measurements of PM10 or PM2.5 and ground measurements.

The database serves multiple purposes, including contributing to the Sustainable Development Goal Indicator 11.6.2, for which WHO is the custodial agency. This indicator focuses on air quality in cities and the annual mean levels of fine particulate matter, such as PM2.5 and PM10. The data also assists in establishing a baseline for air pollution globally, allowing for progress tracking, comparisons, and advocacy for necessary actions.

The measurements in the database are localized, with city averages calculated as an average of ground measurement stations. However, it's important to acknowledge the heterogeneity of measurement methods and techniques used, as well as the different temporal coverage of certain measurements. For instance, if data was collected for only part of the year, it may deviate significantly from the annual mean due to seasonal variability.

The WHO's comprehensive database helps address the critical issue of air pollution, which poses a significant threat to global health. By providing valuable insights into air quality in various human settlements, the database supports informed decision-making, policy development, and initiatives to improve air quality and safeguard public health.

The monitoring data should be collected throughout the year and over several years to reduce bias due to seasonal fluctuations

The World Health Organization (WHO) maintains an Ambient Air Quality Database that compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) in more than 100 countries. The data is collected to represent an average for the city or town as a whole, rather than individual stations. The database is updated regularly every 2-3 years and serves as a critical tool for countries and the global community to establish baselines, track progress, and advocate for actions to improve air quality.

To ensure the accuracy and reliability of the data, it is recommended that monitoring data be collected throughout the year and over several years. This approach helps to reduce bias due to seasonal fluctuations and the potential impact of a non-representative year. Seasonal variations can significantly influence air quality, and collecting data year-round provides a more comprehensive understanding of pollution levels. For example, factors such as increased energy consumption during winter months or higher levels of pollen and plant emissions during the summer can impact air quality. By collecting data across different seasons, we can identify and account for these fluctuations, ensuring that the data accurately reflects the annual pollution levels.

Additionally, collecting data over several years helps to account for any unusual or extreme events that may occur in a given year, such as wildfires, heatwaves, or industrial incidents, which can significantly impact air quality. By including data from multiple years, we can identify and smooth out these anomalies, providing a more robust and representative picture of long-term air quality trends. This long-term perspective also enables us to track the effectiveness of pollution control measures and identify any areas where additional efforts may be required.

It is also important to ensure that the monitors used for data collection are not unduly influenced by a single source of pollution, such as a power plant or a highway. Instead, the monitors should reflect exposures over a wide area, including urban, residential, commercial, rural, and industrial areas. This comprehensive approach ensures that the data captures the diverse pollution levels experienced by different communities and helps identify areas where targeted pollution control measures may be needed.

By collecting monitoring data throughout the year and over several years, we can reduce bias, account for seasonal variations, and obtain a more accurate understanding of air quality. This robust data enables policymakers, scientists, and communities to make informed decisions, advocate for change, and implement effective strategies to improve the health and well-being of people affected by air pollution.

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