by Samyra Sosa

The Metropolitan Air Quality Index is based on the Environmental Standard of the Federal District NADF-009-AIRE-2006 and is an indicator designed to inform the population about the state of air quality.

In recent weeks, high temperatures and even historical records have been reported in Mexico City due to rising temperatures. Here, EL UNIVERSAL explains the measurement of air quality and UV radiation.

The National Water Commission (Conagua) predicted at least five heat waves during 2024, with high temperatures causing forest fires and poor air quality.

The Atmospheric Monitoring System reports on circumstances and areas at risk due to ozone levels or concentration of environmental particles (PM).

What is the Metropolitan Air Quality Index (IMECA)?

The IMECA is an indicator designed to inform the population about air quality conditions, indicating how polluted the air is and potential health effects. Since 2006, the IMECA has been based on the Environmental Standard of the Federal District NADF-009-AIRE-2006, calculating for five criterion pollutants: sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone, and suspended particles.

The purpose of the IMECA is categorized into five levels, each corresponding to an interval in the index and indicating the health risk level, on a scale from 0 to 500, where 100 represents the value indicated by the Official Mexican Standard for each pollutant.

What is the Solar UV Intensity Index?

Sunlight is the primary source of UV radiation, although lamps and tanning beds also emit this radiation. Prolonged exposure to UV radiation can have health effects, especially on the skin (cancer) and eyes (cataracts).

The UV index is a measure of solar UV radiation intensity at the Earth’s surface, expressed as a value above zero, where higher values indicate a greater likelihood of skin and eye damage.

Therefore, it’s important to take basic sun protection measures:

-Reduce sun exposure, especially during peak hours from 11 a.m. to 4 p.m.
-Seek shade and use protective clothing.
-Wear a wide-brimmed hat and sunglasses.
-Apply sunscreen with sun protection factor.
-Avoid tanning beds.

What are PM10 and PM2.5 particles?

According to the World Health Organization (WHO), particulate matter is an indicator of air pollution consisting of solid and liquid particles of organic and inorganic substances suspended in the air, composed of sulfates, nitrates, ammonia, sodium chloride, soot, mineral dust, and water.

The United States Environmental Protection Agency (EPA) indicates that particle size is linked to potential health problems, with the smallest particles of less than 10 micrometers in diameter causing the greatest problems.

The most common are fine particles of 2.5 micrometers or less in diameter (PM2.5) and coarse particles of 10 micrometers in diameter (PM10), which are major climate-affecting atmospheric pollutants, despite having a shorter lifespan than greenhouse gases.

What is Ozone?

According to the National Center for Disaster Prevention (CENAPRED), ozone is a gas naturally present in the atmosphere at very low concentrations. In the upper layers, it protects us from UV radiation from the sun, but at ground level, it can be harmful to health.

Ozone is considered an environmental pollutant, as high concentrations can cause health issues like irritating the respiratory system, worsening asthma and chronic lung diseases, reducing lung function, and decreasing life expectancy.

In cities, ozone can form in high concentrations due to chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.

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