PM2.5 stands for particulate matter 2.5 microns or smaller. These particles are 30 times thinner than a human hair and come from car exhaust, power plants, wildfires, and burning fuel. They are small enough to bypass your body's natural defenses and enter your bloodstream.

How does air pollution affect the body?

Air pollution affects virtually every organ in the body. PM2.5 particles enter your lungs, pass into your bloodstream, and travel to your heart, brain, kidneys, liver, and other organs. This causes chronic inflammation, increasing risks of heart disease, stroke, lung cancer, dementia, and many other conditions.

How many people are affected by air pollution?

99% of the global population breathes air that exceeds WHO safety guidelines. Air pollution kills approximately 8 million people every year—more than AIDS, malaria, and tuberculosis combined.

Costa Rica's Alajuela Air Pollution Report

Overview

Air Pollution in Alajuela

Alajuela faces significant air pollution challenges. 100% of districts exceed the WHO guideline for clean air. This is putting 1.1 million across 16 districts at risk.

The average PM2.5 over 2023 was 13.9µg/m³. That's 2.8 times the WHO guideline for clean air of 5µg/m³.

This is equivalent of everybody, including children, smoking about 231 cigarettes in a year.

Trends

Air Quality Trend

Annual PM2.5 levels from 2014 to 2023. The WHO guideline for safe air is 5 µg/m³.

Health Impact

Life Expectancy Impact

If Alajuela met the WHO guideline of 5 µg/m³, the average person would live 0.86 years longer.

That's 906K years of life stolen from 1.1 million people. Years of watching children grow up. Years of building a career. Years of quiet mornings and celebrations.

Lives cut short. Breathing kills.

Most Polluted

Districts with Highest Pollution

The top 10 most polluted districts in Alajuela. These areas face the greatest health burden from air pollution.

1.San Ramón
0.9 years lost
2.Palmares
0.9 years lost
3.Zarcero
0.9 years lost
4.Atenas
0.9 years lost
5.Naranjo
0.9 years lost
6.Alajuela
0.9 years lost
7.Upala
0.9 years lost
8.Guatuso
0.9 years lost
9.Grecia
0.8 years lost
10.Poás
0.8 years lost

Exposure

Population Exposure by Pollution Level

Distribution of population across different PM2.5 pollution levels. The WHO guideline is 5 µg/m³—only populations below this threshold are breathing safe air.

< 5 µg/m³

5-10 µg/m³

10-15 µg/m³

100%

1.1M

15-25 µg/m³

25-35 µg/m³

> 35 µg/m³

Districts

All 16 Districts in Alajuela

Complete air quality data for every district in Alajuela, sorted by population.

District	Population	PM2.5 µg/m³	Years Lost
Alajuela	321K	14.1	0.9 years
San Carlos	205K	13.3	0.8 years
San Ramón	96K	14.4	0.9 years
Grecia	76K	13.7	0.8 years
Upala	55K	14.0	0.9 years
Naranjo	50K	14.2	0.9 years
Palmares	42K	14.4	0.9 years
Poás	35K	13.7	0.8 years
Los Chiles	34K	13.3	0.8 years
Atenas	30K	14.4	0.9 years
Orotina	24K	13.1	0.8 years
Sarchí	23K	13.6	0.8 years
Guatuso	20K	13.9	0.9 years
Río Cuarto	19K	13.2	0.8 years
Zarcero	15K	14.4	0.9 years
San Mateo	7K	13.1	0.8 years

Showing 16 districts, sorted by population (largest first). PM2.5 values are for 2023. Years lost calculated against WHO guideline of 5 µg/m³.

Breathing in Alajuela is Injurious to Health.