Air Quality
Annual mean concentration of particulate matter with diameter of 2.5 micrometers or less (roughly 3% of the width of a human hair).
Why did we include this measure?
Our lungs are designed to provide oxygen to the body and to remove pollution that interferes with basic bodily functions. However, this only works for larger particles that our bodies can filter out—not tiny particles. The main source of these tiny particles is combustion of fossil fuels—the same source as greenhouse gas emissions (transportation, electricity generation, etc.). This particulate matter directly enters our respiratory systems and bloodstreams and can bypass the usual defenses. This appears to create harmful breathing problems (asthma and bronchitis) and an increased risk of heart attacks, strokes, and hypertension.
How does the US rank globally?
- Specific Measure: (Same as above.)
(Source: Authors’ analysis of World Health Organization data).
- Percentage of countries the US outperforms: 73% (out of 30 countries)
- International Rank Trend: Worsening
National Trend Improving
What do the data show?
Particulate matter has declined by almost 50% since the year 2000, and we rank ahead of almost three-quarters of higher-income countries, just behind Denmark, Sweden, and Portugal. However, other countries are improving faster than we are, so our relative position is declining.
What might explain these patterns?
Given that greenhouse gas emissions and particulate matter have the same sources, the decline in the burning of fossil fuels partly explains the decline in particulate matter. But particulate matter has declined much more quickly than carbon dioxide emissions because it has been subject to government regulations.
For more information about data sources and treatments, download the Data Notes.