What are the trends in air quality since 1990?

What are the global trends in PM2.5 exposures from 1990 to 2016?

Globally, fine particulate matter (PM2.5) concentrations (calculated in µg/m3 as population-weighted annual averages) have been climbing steadily from about 43 µg/m3 in 1990 to 51 µg/m3 in 2016, an increase of about 27%. Some of the steepest increases have occurred since 2010, driven by increases in a relatively small number of highly populated countries.

Trends in population-weighted annual average PM2.5 concentrations in the 10 most populous countries plus the European Union, 2010–2016.

 [Figure E, © HEI]


The figure shows the global PM2.5 concentration trends from 2010 to 2016 compared with trends in the world’s 10 most populous countries and the European Union (see Explore the Data for all years 1990 to 2016). 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 26 years. 

Where have increases in PM2.5 concentrations occurred?

India, Bangladesh, Pakistan, and China have all experienced some of the highest exposures to PM2.5 globally, but the trends in these countries are markedly different in some cases. Pakistan, Bangladesh, and India have experienced the steepest increases in air pollution levels since 2010 and now present the highest sustained PM2.5 concentrations among the countries shown here.

Although China experienced substantial increases in population-weighted exposures before 2010 — reflecting in part the dramatic scale of economic development over the last 25 years — exposures since have started to stabilize and even decline slightly.

The dramatic increases in PM2.5 concentrations in Nigeria illustrated here are likely to have resulted from an extensive dust storm in late 2015 and early 2016. However, longer-term trends in the data suggest declines in PM2.5 exposures in Nigeria.

Among the most populated regions of the world, Russia, Indonesia, the European Union, Japan, and Brazil continue to have among the lowest PM2.5 levels of the countries shown here. However, none of these countries yet meets the WHO Air Quality Guideline for healthy air.

What are the trends for ozone exposures over the last 26 years?

Globally, population-weighted seasonal average ozone concentrations have continued to increase since 1990, led by upward trends in South and East Asia and in tropical Latin America. The increases reflect a combination of factors, including increased emissions of ozone precursors such as nitrogen oxides coupled with warmer temperatures, especially at mid-latitudes in rapidly developing economies. The levels and trends in ozone concentrations for individual countries from 1990 to 2016 can be explored using the interactive tools in Explore the Data.

What are the trends in exposure to household air pollution?

Although large numbers of people worldwide are still exposed to household air pollution, the numbers have been declining in many regions of the world over the last 26 years. Some of the most dramatic declines have occurred in Asia, southern Africa, and throughout most of South America, most significantly in middle- and high-income countries. China, for example, has reduced the population relying on solid fuels from about 996 million in 1990 to about 416 million in 2016. On the other hand, there has been little change in East, Central, and West sub-Saharan Africa where the proportions of population exposed to household air pollution have remained the highest.

Trends in the proportion of population exposed to household air pollution from burning of solid fuels for selected regions of the world.

[Figure F, © HEI]


Explore the data 

You can explore patterns and trends in exposure to fine particulate matter, ozone, and household air pollution in 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.