Air Quality Health Impact Calculator
Estimate the annual economic health burden of PM2.5 air pollution on a population. Use it when assessing urban air quality policy, environmental impact studies, or public health planning.
Last updated: September 2026
Formula below · 2 sources (climate.gov, Wikipedia) · Updated Sep 2026
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About this calculator
Fine particulate matter (PM2.5) causes measurable health damage at any sustained concentration; this calculator counts exposure above 10 μg/m³ (the WHO 2005 annual guideline — the 2021 WHO guideline is 5 μg/m³ and the US EPA annual standard is 9 μg/m³ since 2024). This calculator quantifies the economic cost of that excess exposure using the formula: Cost = round(max(PM2.5 − 10, 0) × 0.008 × population × (exposureHours / 24) × ageRiskFactor × healthcareCost × 0.01). The excess concentration (above 10 μg/m³) drives the base risk. Multiplying by 0.008 applies an assumed risk coefficient linking exposure to health events; the result is an illustrative estimate, not a calibrated health-impact assessment such as EPA BenMAP. Daily exposure fraction (hours/24) scales for part-time outdoor exposure, while the age risk factor accounts for vulnerability differences across age groups. The result is the estimated annual economic health impact in dollars for the affected population.
How to use
Suppose a city of 50,000 people experiences PM2.5 of 35 μg/m³, with 8 hours of daily outdoor exposure, an age risk factor of 1.2, and average healthcare costs of $3,000/person/year. Step 1: Excess PM2.5 = 35 − 10 = 25 μg/m³. Step 2: 25 × 0.008 × 50,000 × (8/24) × 1.2 × 3,000 × 0.01 = 25 × 0.008 × 50,000 × 0.333 × 1.2 × 3,000 × 0.01 = $120,000. The calculator performs this multiplication and rounds to two decimal places, giving the annual estimated health cost.
Frequently asked questions
What does PM2.5 level mean and why does 10 μg/m³ matter in this calculator?
PM2.5 refers to airborne particles smaller than 2.5 micrometres, which penetrate deep into the lungs and bloodstream. The WHO's 2005 annual guideline was 10 μg/m³; its 2021 update lowered it to 5 μg/m³, and the US EPA annual standard is 9 μg/m³. This calculator treats any PM2.5 above 10 μg/m³ as 'excess' exposure that drives health risk, so concentrations at or below 10 produce zero estimated impact. Regions consistently above this threshold face measurable increases in respiratory and cardiovascular disease rates.
How does the age group risk factor affect the health impact estimate?
Certain populations — particularly children under 5 and adults over 65 — are significantly more vulnerable to PM2.5 exposure than the general working-age population. The age risk factor (entered as a numeric multiplier) scales the output to reflect this heightened susceptibility. A factor of 1.0 represents working-age adults and 1.1 a mixed population, while higher values (1.2 children, 1.4 elderly) increase the estimated impact for more vulnerable groups. Choosing the correct age group factor makes the estimate more representative of real-world public health costs.
Why are daily exposure hours important when calculating air pollution health costs?
Not everyone is exposed to outdoor air pollution for a full 24 hours. People who spend most of their time indoors — where filtration and building envelopes reduce PM2.5 levels — accumulate far less exposure than the outdoor ambient concentration would suggest. The exposure fraction (hours ÷ 24) adjusts the health impact proportionally. For example, 8 hours of outdoor exposure represents only one-third of the maximum possible dose, substantially reducing the calculated economic burden compared to continuous outdoor exposure.