THE State of Global Air is a research and outreach initiative of the United States’ Health Effect Institute and the Institute for Health Metrics and Evaluation’s Global Burden of Disease project. In collaboration with the United Nations International Children’s Emergency Fund, the State of Global Air has published the State of Global Air Report 2024 on June 18. The report has presented information on exposures to and health impact of exposure to common air pollutants including fine particulate matter (PM2.5), ozone (O3), and for the first time, nitrogen dioxide (NO2).
Along with the publication, the State of Global Air through on its web site has made public the air quality data from 1990 to 2020 of all the countries. This report offers a great significance on the reflection of air quality status of Bangladesh in the midst of the continued propaganda on the dire situation of air pollution. It is worth noting that earlier this year, another global report was published by an international group IQAir-AirVisual, where Bangladesh with the mean population-weighted PM2.5 concentration of 79.9 µg/m3, was shown as the most polluted country.
Contrasted to that, the State of Global Air data reveal that Bangladesh with mean population-weighted PM2.5 concentration of 42.4 µg/m3 was standing in the 21st position among the countries in 2021 (See table). The major fundamental issue lay in this difference between the two global reports was the way they produced the data. While the IQAir received data from some of the urban air monitoring stations and extrapolated it on to the whole country, the State of Global Air collected data from all the available reference instrument operating throughout the country as well as used satellite and global chemical transport model to produce air quality data in the places where no instrument for air quality monitoring was running. Thus, the State of Global Air results reflect much accuracy in the context of the whole country whereas the IQAir report suits better for urban status such as for the Dhaka city.
The State of Global Air data reveal that PM2.5 concentrations were decreasing globally. The global average exposure for ambient PM2.5 in 2020 was 31.3 µg/m3. However, air pollution in the African countries, the Middle East and the South Asia is still far from the target set by the World health Organisation. Worldwide, eight of the 10 countries with the highest PM2.5 exposures are in Africa and the remaining two are in the Middle East. Major sources of PM2.5 in the Middle East and North Africa include dust, power plants, transport and industries while in South Asia the sources include residential fuel use, energy generation, industries and agriculture. It is important to note that the high PM2.5 exposures in North and West Africa are influenced by windblown mineral dust whereas those in South Asia are mostly anthropogenic.
The South Asian countries have shown a very good progress in improving their PM2.5 exposure in five years. Compared with 2016, population-weighted PM2.5 concentrations in Bangladesh, India, Nepal and Pakistan has dropped by about 33.5, 36.0, 36.8 and 37.2 per cent respectively in 2020 although the number of death from air pollution in these countries has not changed much in recent years. However, the ambient O3 concentration in these countries has increased by about 15–20 per cent in the past decade.
According to State of Global Air, the total number of death associated with the exposure to air pollution globally is calculated at 8.1 million in 2021, which is about 21.6 per cent greater than the number estimated in the earlier report of 2019. Advancement in scientific research on the assessment of health impact of air pollution has led to find more death in the latest report and to know that air pollution is the second largest risk factor of death in 2021 just behind high blood pressure, compared with its fourth position of the risk factors shown in the previous report in 2019. Ambient PM2.5 and household air pollution was responsible for 58.0 and 38.0 per cent of the total number of death in 2021.
The matter of hope is that the death from the exposure to household air pollution has decreased by 36.0 per cent in 20 years and as a consequence, the impact on the children under 5 has declined by around 35.0 per cent in 10 years. This success has come mainly because of the widespread adaptation of cleaner fuel for cooking and room heating in China and South Asia. India and China together share most of the deaths (~54.0%) because of the impact of air pollution while the number of death in some of other populated countries in 2021 are as follows: Pakistan (256,000), Bangladesh (236,300), Indonesia (221,600), Nigeria (206,700), Egypt (116,500) and Myanmar (101,600).
Most of the death (~96.3 per cent) are associated with PM2.5 exposure (58.0 per cent with ambient PM2.5 and 38.3 per cent with household PM2.5). Of all the death attributable to ambient PM2.5 in 2021, heart disease-related death are linked to 19Ìý per cent (or ~1.5 million). It is important to know that long-term exposure to high level of PM2.5 is associated with illness and early death from diseases, including heart diseases, lung cancer, chronic obstructive pulmonary diseases, stroke, Type 2 diabetes, lower respiratory infections, etc. Ozone pollution was responsible for 6.0 per cent of the total number of death in 2021.
State of Global Air Report 2024 has dedicated a special chapter to the health impact of air pollution on children under 5. It claims that air pollution caused death of 700,000 children under 5 in the world in 2021, tagging it as the second leading cause, after malnutrition. In Bangladesh, more than 40 per cent of all deaths from lower respiratory infection in children under 5 are attributed to air pollution. It is studied that being exposed to air pollution in the womb increases the likelihood that a baby will be born too small (low birth weight) or too early (pre-term birth). The conditions, in turn, make babies more susceptible to lower respiratory and other serious infections.
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Md Masud Rana is an air quality expert, Nature Conservation Management.
