Air Quality Index Calculator
Compare a country's average PM2.5 air quality against WHO guidelines and see how it ranks globally.
Source: WHO Global Health Observatory (SDGPM25) · 2023 · last verified 2026-09-12
How this is calculated
Your country's annual mean PM2.5 is compared against the WHO guideline of 5 µg/m³ for an exceedance multiple and health risk classification, and ranked against every other covered country for a global percentile. PM2.5 is used as the benchmark pollutant because it is the pollutant most strongly and consistently linked to premature death and chronic disease across the largest body of epidemiological research, making it the standard yardstick for comparing air quality between countries.
An exceedance multiple of 3× means a country's annual PM2.5 average is three times the WHO guideline — common in many of the world's most polluted regions. Air quality is closely tied to two other topics covered elsewhere on this site: much of the fine particulate pollution that drives PM2.5 levels comes from the same fossil-fuel combustion that drives carbon emissions, and a country's electricity grid carbon intensity is often a useful proxy for how much of its air pollution comes from power generation specifically.
Frequently asked questions
- What is the WHO guideline?
- The WHO Air Quality Guidelines (2021) recommend an annual mean PM2.5 exposure of no more than 5 µg/m³.
- What does "global percentile" mean here?
- Where a country ranks among all covered countries sorted by PM2.5 — a lower percentile means cleaner air relative to the rest of the list.
- Measured vs modelled?
- Some countries' figures come from dense ground-monitoring networks (measured); others rely more on satellite and atmospheric modelling (modelled) due to sparser monitoring infrastructure.
- What is PM2.5 and why is it the key measure?
- PM2.5 refers to fine particulate matter 2.5 micrometres or smaller in diameter — small enough to penetrate deep into the lungs and enter the bloodstream. It is considered the single most health-damaging air pollutant, which is why it is the primary metric in most air quality guidelines and indices.
- What does the WHO guideline of 5 µg/m³ mean?
- It is the annual mean PM2.5 concentration the WHO recommends as an upper limit for minimising health risk, updated and tightened in the 2021 WHO Air Quality Guidelines. Most of the world's population currently lives in areas that exceed this guideline.
- What is an AQI and how does it relate to PM2.5?
- An Air Quality Index (AQI) is a standardised scale (often 0–500) that converts pollutant concentrations — including PM2.5, but also others like ozone and NO2 — into a single number and category (e.g. "Good", "Unhealthy"). This tool focuses specifically on annual mean PM2.5 rather than a composite daily AQI.
- Which countries have the worst and best air quality?
- Countries in South Asia (particularly India, Pakistan, and Bangladesh) and parts of the Middle East and West Africa consistently report the highest annual PM2.5 levels, often many multiples of the WHO guideline. Countries with the cleanest air are typically ones with strong emissions regulation, low population density, or favourable geography — Nordic countries, Australia, and New Zealand rank among the best.
- What health effects does long-term PM2.5 exposure cause?
- Long-term exposure is linked to increased risk of respiratory and cardiovascular disease, stroke, lung cancer, and reduced life expectancy. The WHO estimates outdoor air pollution contributes to millions of premature deaths globally each year, making it one of the largest environmental health risks worldwide.