What is the Air Quality Index (AQI)?
The Air Quality Index, known as AQI, is a tool used by environmental and meteorological agencies to inform the public about how clean or polluted the air is at a given time. The AQI focuses on the health effects that air pollution can have, especially in the hours following exposure.
In South America, the AQI has become essential for natural risk management and agricultural planning, as air quality can affect everything from human health to crop productivity.
How is the AQI Calculated?
The AQI is calculated based on five main pollutants regulated by the Clean Air Act:
- Ground-level ozone (O₃)
- Particulate matter (PM2.5 and PM10)
- Carbon monoxide (CO)
- Sulfur dioxide (SO₂)
- Nitrogen dioxide (NO₂)
Each pollutant has a scale from 0 to 500. The higher the value, the greater the level of pollution and health risk. The final AQI value corresponds to the pollutant with the highest concentration at that time.
The Six AQI Levels and Their Meaning
The AQI is divided into six categories, each with a color and a level of health concern:
1. Good (0-50) — Green
Air quality is satisfactory, and pollution poses little or no risk. Ideal for outdoor activities and agriculture.
2. Moderate (51-100) — Yellow
Air quality is acceptable, but for some pollutants, there may be a moderate health concern for a very small number of sensitive individuals (e.g., asthmatics or children).
3. Unhealthy for Sensitive Groups (101-150) — Orange
Sensitive groups may experience health effects. The general public is less likely to be affected. Prolonged outdoor exposure should be reduced.
4. Unhealthy (151-200) — Red
Everyone may begin to experience health effects; members of sensitive groups may experience more serious effects. It is best to limit outdoor activities.
5. Very Unhealthy (201-300) — Purple
Health alert: everyone may experience serious effects. All outdoor activities should be avoided.
6. Hazardous (301-500) — Maroon
Emergency conditions: the entire population is likely to be affected. Authorities' instructions should be followed.
Why is the AQI Important in South America?
In South America, the AQI is especially relevant due to factors such as wildfires in the Amazon, agricultural burning in the Southern Cone regions, and urban pollution in large cities like Santiago de Chile, São Paulo, or Buenos Aires. These events can drastically increase levels of fine particulate matter (PM2.5), affecting the respiratory health of millions of people.
Furthermore, in the agricultural sector, air quality influences photosynthesis and crop yield. A high AQI can reduce available solar radiation, affecting the growth of crops such as soybeans, corn, or wheat.
How to Use the AQI in Your Daily Life
To make the most of this tool, follow these practical tips:
- Check the AQI daily through apps like Contingencias, which integrate real-time data from monitoring stations.
- Plan outdoor activities according to the level: if the AQI exceeds 100, reduce intense outdoor exercise.
- Protect vulnerable groups: children, the elderly, and people with respiratory illnesses should avoid exposure when the AQI is orange or higher.
- In agriculture, monitor the AQI to schedule fumigations or harvests, avoiding days with high pollution that could interfere with crops' biological processes.
Differences Between the AQI and Other Indices
It is important not to confuse the AQI with the UV Index or the Air Quality Index (ICA) used in some countries. While the AQI focuses on pollution, the ICA may include other parameters such as pollen or humidity. At Contingencias, we unify these metrics to provide you with a comprehensive view of weather and risks.
Conclusion
The Air Quality Index is a powerful and accessible tool for protecting your health and optimizing activities like agriculture. Interpreting it correctly allows you to make informed decisions, from when to go for a run to when to harvest your crops. Stay alert, check the AQI daily, and protect your well-being and that of your community.