Air quality in Medellin

What is the current level of air pollution in Medellin city?

Medellín, officially the Municipality of Medellín, is the second-largest city in Colombia, after Bogotá, and the capital of the department of Antioquia. It is situated in the Aburrá Valley, a central region of the Andes Mountains in South America. A census conducted in 2018 found that Medellin had an estimated population of approximately 2,500,000 people. When taking into account the nine other cities within the metropolis the population figure expands to over 3.7 million people which makes Medellin the second-largest urban conglomeration in Colombia.

The state of the air in August 2021 was “Moderate” with a US AQI reading of 57. This United States Air Quality Index number is calculated using the levels of six of the most prolific air pollutants, such as nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and both sizes of particulate matter, being PM2.5 and PM10. It can then be used as the metric when comparing air quality in other cities around the world. If data is unavailable for all 6 pollutants, a figure can still be calculated by using what figures there are.

For Medellin, the only record was for PM2.5 which was 15 µg/m³. This figure is one and a half times the recommended level of 10 µg/m³ which is the suggested maximum figure by the World Health Organisation (WHO), although no amount of air pollution is considered to be safe.

With a level such as this, the advice would be to stay indoors and close the windows and doors to prevent the ingress of more polluted air. Those who are sensitive to poorer air quality should avoid undue outdoor contact. If journeying outside is unavoidable, then a good quality particle filtering mask should be worn at all times. The table that is published at the top of this page should help with that decision or download the AirVisual app for constant updates as to the state of the air in real-time.

Does the level of pollution stay the same throughout the year in Medellin?

Air pollution can be very volatile and change very quickly depending on meteorological conditions. Looking at the figures published by IQAir.com for 2020, it can readily be seen that the worst month for air quality was March when a figure of 41.9 µg/m³ was recorded. This places it in the “Unhealthy for sensitive groups” category with figures between 35.5 and 55.4 µg/m³ to be classed as such. The remaining 11 months of the year were all classified as being “Moderate” with figures between 12.1 and 35.4 µg/m³. It seems that the best time of year for air quality is from April until August with figures ranging from 13.3 to 15.7 µg/m³.

Records relating to air pollution were first kept in 2019 when a figure of 19.9 µg/m³ was recorded. This, again, put Medellin in the “Moderate” air quality category. The following year of 2020 saw a slight improvement with a recorded figure of 19.1 µg/m³. This coincided with the COVID-19 pandemic when many vehicles were no longer in daily use in an attempt to halt the spread of the virus. Many factories and non-essential production units were also required to close which removed their emissions from the atmosphere and therefore, most cities revealed very good figures for air quality. Often much lower than their usual standards.

Where does the air pollution come from in Medellin?

As much as 80 per cent of Medellin’s pollution is emitted by mobile sources. Dumper trucks and trucks are the ones that pollute the most (59%), followed by the 750,000 motorcycles that circulate through the territory daily (23%), then buses (10%), private vehicles (6%) and, finally, taxis (2%). In the gas emission controls, between 40 and 50 per cent of the evaluated vehicles do not pass the required standards tests.

The growth of the vehicle fleet also has important effects. While in 2005 478,000 vehicles circulated in Medellín, in 2016 the traffic of 1,400,000 vehicles was reported. 90 per cent are cars and motorcycles.

The topography of the area exacerbates the problem because Medellin sits in a valley, only 7 kilometres wide which traps the air inside. A phenomenon known as temperature inversion.

The air quality of the Aburrá Valley which is the conurbation around Medellín, Colombia's second city, which includes a total of ten municipalities and just over 3.5 million inhabitants has become harmful to the health of its inhabitants: concentration of PM2.5 particles that can enter the bloodstream, exceeded the limit of 55 micrograms per cubic meter, a level considered in the city the limit to declare a red alert.

Can anything be done to reduce air pollution in Medellin?

The latest plan proposed by the mayor includes 10 points that include, among other things, the financing of electric bicycles, an increase in charging stations for electric mobility, the transformation to gas of brickyards and industries. The first line of the plan is that EPM will finance a minimum of 50,000 electric bicycles, which will be accompanied by the second point, which is to double the charging stations for electric mobility. Third, there will be a transformation of brickworks and industries, to gas.

Another of the actions involves the students of the public educational institutions of the municipality, who will take part in the planting of 70,000 trees in the surrounding area.

What are the detrimental effects of air pollution in Medellin on our health?

Air pollution causes serious risks, harm or annoyance to people. It can enter by 3 routes or means: respiratory, cutaneous or digestive route; and its actions in the body can be irritating, suffocating, narcotic or toxic.

Among its effects are: headaches, dizziness, nausea, vomiting and dyspnoea, through visual disturbances, disorientation, loss of consciousness, even respiratory infections, such as bronchitis and pneumonia, decreased lung function, arrhythmias, acute vascular accident and death.

Epidemiological studies from around the world show that this contamination generates an increase in asthma symptoms, and chronic effects at the respiratory and cardiovascular level. If exposure to pollutants is high and prolonged, it can lead to death from respiratory and cardiovascular diseases.

The concentration of PM2.5 particulate matter is the key to identifying air quality. Particulate Matter comes mainly in two noticeable sizes, PM2.5 and PM10. The number value indicates the diameter of the substance. PM2.5 are particularly hazardous because of their size. On that microscopic scale, they can easily bypass the body’s natural defence system and penetrate deep inside the lungs. Once in the lungs, they travel to the base of the bronchial tubes where they lodge in the alveoli. These are the millions of air sacs that a body has to exchange oxygen for carbon dioxide. From here, they can also enter the bloodstream.