Ambient Air Pollution: Database And Symbaloo Guide

The World Health Organization (WHO) has been compiling and publishing ground measurements of air quality since 2011. The WHO Ambient Air Quality Database collects data on the annual mean concentrations of nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) to represent air quality in cities and towns. The database is regularly updated and provides critical information for global assessments and efforts to mitigate health risks associated with air pollution, which is currently the largest environmental risk to health. The data is used to establish baselines, track progress, and advocate for actions to improve air quality and protect public health.

Annual mean concentrations of nitrogen dioxide (NO2)

Nitrogen dioxide (NO2) is one of the principal nitrogen oxides associated with combustion sources. It is a strong oxidant, corrosive, and poorly soluble in water. In ambient conditions, both outdoors and indoors, nitrogen dioxide exists in its gaseous form, and inhalation is the major route of exposure. Direct contact with the eyes may lead to eye irritation, although this is more likely to occur in industrial settings after accidental contact with high gaseous nitrogen dioxide concentrations.

The WHO Ambient Air Quality Database compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2) to represent the average for a city or town as a whole. The database is updated regularly every 2-3 years and was last updated in January 2024. The data is used to derive the Sustainable Development Goal Indicator 11.6.2, Air quality in cities. The primary sources of data are official reports of countries sent to the WHO, official national and subnational reports, and national and subnational websites that contain measurements of NO2. The WHO also uses modelled estimates that rely on information available in the WHO Ambient Air Quality Database when ground monitors are not available.

The annual mean concentrations of NO2 in urban areas throughout the world are generally in the range of 20–90 μg/m3. In the European Community Respiratory Health Survey (ECRHS II), which covered 21 European cities, annual ambient nitrogen dioxide concentrations ranged from 4.9 μg/m3 in Reykjavik to 72 μg/m3 in Turin. The maximum hourly mean value may be several times higher than the annual mean. For example, a range of 179–688 μg/m3 of nitrogen dioxide has been reported inside a car in a road tunnel during rush hour.

The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb. The form of the 1-hour standard is the 3-year average of the 98th percentile of the yearly distribution of 1-hour daily maximum NO2 concentrations.

Particulate matter of a diameter ≤ 10 μm (PM10)

Particulate matter (PM) refers to a wide range of tiny solid or liquid substances that float in the air. PM is frequently classified by size according to its aerodynamic diameter. PM10 refers to "coarse particulate matter", which includes particles with a diameter of 10 micrometres or less. Other categories include PM2.5, or "fine particulate matter", which includes particles with a diameter of 2.5 micrometres or less, and PM0.1, or "ultrafine particulate matter", which includes particles with a diameter of 0.1 micrometres or less.

The World Health Organization (WHO) has been compiling and publishing ground measurements of air quality, including the annual mean concentrations of particulate matter, since 2011. The WHO Ambient Air Quality Database includes data on ground measurements of PM10, which originate mainly from human activities related to fossil fuel combustion. The database is updated regularly every 2-3 years and is used to derive the Sustainable Development Goal Indicator 11.6.2, Air quality in cities, for which the WHO is the custodial agency. The data is also used to derive robust estimates of population exposure for studies of the burden of disease analysis due to ambient air pollution.

The current WHO annual standard for PM10 is 20 μg/m3. Long-term exposure to high levels of PM10 can cause significant damage to the immune, respiratory, circulatory, and endocrine systems, and may even lead to cancer. It can also interfere with development and cognition and cause oxidative stress, inflammation, cerebral vascular injury, and neurological disorders.

The US EPA has set national standards to protect against the health and welfare effects associated with ambient exposures to fine and coarse particles. The current US primary national 24-hour standard for PM10 is 150 μg/m3.

Particulate matter of a diameter ≤ 2.5 μm (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 includes data on PM2.5, or particulate matter with a diameter of 2.5 μm or less. PM2.5 is classified as fine particulate matter, and these particles are known to pose a significant risk to human health.

PM2.5 particles are emitted directly from sources such as construction sites, unpaved roads, fields, smokestacks, and fires. They are also formed in the atmosphere through complex reactions of chemicals like sulfur dioxide and nitrogen oxides, which are pollutants released from power plants, industries, and automobiles. These particles are microscopic solids or liquid droplets that can be inhaled, causing serious health issues. Due to their small size, they can penetrate deep into the lungs, and may even enter the bloodstream.

The health risks associated with PM2.5 exposure include respiratory infections and diseases, lung cancer, and selected cardiovascular diseases. The World Health Organization has set a standard for PM2.5 levels, recommending that they should not exceed 25 µg/m3 of air in a 24-hour period. However, it is estimated that 92% of the world's population lives in areas where the annual mean PM2.5 levels exceed this standard.

To address the health risks posed by PM2.5, regulatory agencies worldwide have started monitoring these fine particles. Additionally, the EPA has implemented national and regional rules to reduce emissions of pollutants that form PM2.5, aiding state and local governments in meeting air quality standards. These efforts are crucial in mitigating the harmful impacts of PM2.5 on human health and the environment.

WHO's database on PM2.5 and other air pollutants serves as a valuable resource for countries and the global community to establish baselines, track progress, and advocate for actions to improve air quality and protect public health. The data collected by WHO helps to derive robust estimates of population exposure, contributing to studies on the burden of disease analysis due to ambient air pollution.

Ground measurements of air quality

The World Health Organization (WHO) has been compiling and publishing ground measurements of air quality since 2011. 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 database is updated regularly every 2-3 years.

The WHO Ambient Air Quality Database compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2), 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 for individual stations. Both groups of pollutants originate mainly from human activities related to fossil fuel combustion. To present air quality data that represents human exposure, the database uses mainly urban measurements, including urban background, residential areas, commercial and mixed areas, or rural areas and industrial areas close to urban settlements.

Ground-level ozone and airborne particles are the two air pollutants that pose the greatest risk to human health. They are also the main ingredients in smog, a type of air pollution that reduces visibility. Ground-level ozone is created when sunlight reacts with certain chemical emissions, such as nitrogen dioxide, carbon monoxide, and methane. These chemicals can come from industrial facilities, car exhaust, gasoline vapors, and other sources. Airborne particles are solid and liquid droplets suspended in the air, which become airborne at construction sites, smokestacks, car exhaust pipes, wildfires, and volcanoes, among other places.

Air quality is typically measured using the Air Quality Index (AQI), which works similarly to a thermometer, indicating changes in the amount of pollution in the air. The AQI has six categories that communicate the level of health concern using specific colors. For instance, Code Green and Yellow indicate that the air is generally safe for everyone, while Code Red and Purple mean the air is unhealthy for everyone. In addition to ground instruments, satellites orbiting the Earth, such as those in NOAA's GOES-R series and the Joint Polar Satellite System (JPSS), also collect information about particles in the air.

Air pollution health risks

Air pollution is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke, or vapour, in quantities and durations that can be harmful to human health. 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, last updated in 2024, compiles data on ground measurements of annual mean concentrations of nitrogen dioxide (NO2), 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 pollutants originate mainly from human activities related to fossil fuel combustion.

The health risks and disease pathways from exposure to ambient air pollution depend on the types and concentrations of pollutants in the air pollution mixture. Fine particulate matter, for example, is a common and critical pollutant in both ambient and household air pollution, leading to negative health impacts. These very small particles can penetrate deep into the lungs, enter the bloodstream, and travel to organs, causing systemic damage to tissues and cells. Exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections, and aggravated asthma from short-term exposure. Long-term or chronic exposure to fine particulate matter increases a person's risk for diseases with a longer onset, such as some non-communicable diseases including stroke, heart disease, chronic obstructive pulmonary disease, and cancer.

In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen. A large study of more than 57,000 women found that living near major roadways may increase a woman's risk of breast cancer. Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's lymphoma. Additionally, a long-term study from 2000 to 2016 found a link between lung cancer incidence and increased reliance on coal for energy generation. Exposure to the air pollutant PM2.5 is associated with an increased risk of death, with research showing that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired.

Children are particularly vulnerable to the health impacts of air pollution. Higher air pollution levels increase short-term respiratory infections, leading to more school absences. Children who play several outdoor sports and live in high-ozone communities are more likely to develop asthma. Children living near busy roads have an increased chance of developing asthma, and those exposed to high levels of air pollutants are more likely to develop bronchitis symptoms in adulthood. Living in communities with higher pollution levels can cause lung damage, and breathing PM2.5, even at relatively low levels, may alter the size of a child's developing brain, increasing the risk for cognitive and emotional problems later in adolescence.

Other factors that influence an individual's level of risk from air pollution include exposure, susceptibility, and access to healthcare. Where someone lives, goes to school, and works makes a difference in how much air pollution they breathe. In general, the higher the exposure, the greater the risk of harm. Susceptibility to the health impacts of air pollution may be higher for individuals who are pregnant, children, older adults, and people living with chronic conditions, especially heart and lung disease. Access to healthcare, including health coverage, a healthcare provider, and access to appropriate health information, may also influence an individual's overall health status and how they are impacted by air pollution.

Frequently asked questions