About this report

This 2021 World Air Quality Report presents an overview of the state of global air quality in 2021. The report is based on PM2.5 air quality data from 6,475 cities in 117 countries, regions and territories around the world. The data used to create this report was generated by tens of thousands of regulatory and low-cost air quality monitoring stations operated by governments, non-profit organizations, research institutions, educational facilities, companies, and citizen scientists around the world.

The PM2.5 data presented here is reported in units of micrograms per cubic meter (µg/m³) and utilizes the latest World Health Organization (WHO) annual PM2.5 air quality guideline and interim targets as a framework for data visualization.

The dataset used to generate this report was derived from the IQAir real-time online air quality monitoring platform, which aggregates, validates, calibrates, and harmonizes data from air quality monitoring stations around the globe.

Additional information on real-time and historic air quality conditions in cities, countries, and regions around the world is available on the IQAir website, with a ranking of annual air quality data for 6,475 cities and an interactive global map of annual city concentrations.

With these resources, IQAir endeavors to engage, educate, and inspire governments, researchers, NGOs, companies, and citizens to work together to improve air quality and create healthier communities and cities.

Executive summary

Air pollution is now considered to be the world's largest environmental health threat, accounting for seven million deaths around the world every year. Air pollution causes and aggravates many diseases, ranging from asthma to cancer, lung illnesses and heart disease. The estimated daily economic cost of air pollution has been figured at $8 billion (USD), or 3 to 4% of the gross world product.

Air pollution affects those that are most vulnerable the most. It is estimated that in 2021, the deaths of 40,000 children under the age of five were directly linked to PM2.5 air pollution. And in this age of COVID-19, researchers have found that exposure to PM2.5 increases both the risk of contracting the virus and of suffering more severe symptoms when infected, including death.

In September 2021, the World Health Organization (WHO) released a timely and ambitious update to its global air quality guidelines, 15 years after the last update released in 2006. Acknowledging the significant impact of air pollution on global health, the WHO cut the recommended annual PM2.5 concentration by half, from 10 µg/m³ down to 5 µg/m³, with the ultimate goal of preventing millions of deaths.

IQAir's annual World Air Quality Report aggregates and compares millions of PM2.5 measurements taken in thousands of locations around the world. The data is gathered over the course of the year from a combination of regulatory and non-regulatory ground-based air quality monitors. Although many areas around the world still lack access to publicly available air quality information, global air quality data continued to increase in 2021.

While the 2020 World Air Quality Report included data from 4,745 locations in 106 countries and regions, the 2021 report coverage expanded to 6,475 locations in 117 countries, territories, and regions. This is in part due to the increasing number of low-cost air quality sensors mostly operated by non-profit organizations, governments, and citizen scientists. The increased number of PM2.5 stations helps to create a more accurate picture of hyper-local air quality, and global air quality.

VIETNAM

PROGRESS

In 2021, Vietnam continued to exhibit a declining trend in annual average PM2.5 concentrations. Peaking in 2019 at a concentration of 34.1 µg/m³, annual PM2.5 concentrations fell in 2021 to 24.7 µg/m³. Despite declining concentrations, none of the 15 Vietnamese cities included in this report met the annual average WHO PM2.5 air quality guideline concentration of 5 µg/m³. Annual average PM2.5 concentrations for the capital city of Hanoi decreased by 4.5% in 2021 compared to 2020, dropping from 37.9 to 36.2 µg/m³ and achieving the WHO's annual PM2.5 Interim Target-3. Air quality in Ho Chi Minh City, Vietnam's most populous city, also improved in 2021 with a decrease in PM2.5 concentration from 22 µg/m³ in 2020 to 19.4 µg/m³ in 2021.

CHALLENGES

As manufacturing activity increased in Vietnam, the country's economy has grown over the past decade, increasing the demand for electricity. In 2020, half of the electricity generated in Vietnam came from coal-fired power plants. Vietnam's usage of fossil fuels for power generation is a primary cause of air pollution, along with exhaust from cars and motorbikes, and factory emissions.

HIGHLIGHT: AGRICULTURAL BURNING

At the UN COP26 conference in 2021, Vietnam vowed to reach carbon neutrality by 2050. With the largest solar power infrastructure in Southeast Asia and the addition of offshore and onshore wind farms, Vietnam is poised for a transition away from the use of fossil fuels to power its growing economy [35]. Actions to achieve carbon neutrality will also have the co-benefit of improving air quality by reducing the use of fossil fuels, the country's major source of air pollution.

Source: IQAir International