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What are the trends in air quality since 1990?

What are the trends in PM2.5 exposures from 1990 to 2015?

Globally, fine particulate matter (PM2.5) concentrations (calculated as population-weighted annual averages) have been climbing steadily since 1990, as shown in the first graph. They have increased by about 11 % overall. Some of the steepest increases in individual countries have occurred since 2010.

The figure shows PM2.5 concentration trends for the world’s 10 most populous countries and the European Union, ranked in order of the concentrations observed in 2015. Overlying these trends are the WHO air quality guideline and interim air quality targets (IT) for marking progress toward the guideline. The figure reveals that the disparity between the countries with the poorest air quality and those with the best air quality has grown substantially over the past 25 years. 

Trends in population-weighted fine particulate matter concentrations in the 10 most populous countries and the European Union (1990–2015).



Where have increases in PM2.5 concentrations occurred?

The increases in global exposure to PM2.5 have been led by increases in Bangladesh and India, particularly since 2010. Ambient particle levels in China increased steadily from 1990 to 2010 but — despite continued dramatic economic growth — did not increase as rapidly in the last 5 years.

Better news for some areas

Russia, Indonesia, the European Union, Japan, and Brazil have experienced declines in PM2.5 concentrations since 1990 and now have among the lowest levels of the countries shown here. However, none of these countries yet meets the WHO Air Quality Guideline for healthy air.

The ability to map and compare trends around the world also brings to light apparent dramatic declines in PM2.5 levels in other countries such as Nigeria. Scientists think this decline may be related to reductions in open burning and windblown dust, but the trend shown is based on limited data and needs to be studied further.

What are the trends for ozone exposures over the last 25 years?

Like PM2.5, population-weighted (seasonal average) concentrations of ozone have been increasing globally. The global trend line in the second graph shows about a 7% increase from 1990 to 2015. Among the 10 most populous countries and the European Union, the largest increases (of 14% to 25%) were experienced in India, Bangladesh, Pakistan, China, and Brazil. The United States and the European Union have experienced small declines in ozone concentrations since 1990 (5% and 2%, respectively).

Trends in seasonal average population-weighted ozone concentrations in the most populous countries and the European Union (1990 to 2015).


Explore the data 

You can explore patterns and trends in fine particulate matter and ozone pollution levels in other countries and regions around the world using the interactive tools in Explore the Data. Compare results in your country with those of other countries in your region or economic group. See the How To page for more detailed instructions.