Should Travellers Be Concerned About The Causes Of Air Pollution In Buenos Aires?

The most significant causes of air pollution in Buenos Aires stem from the high concentration of unregulated vehicle pollutants throughout the city during peak hour when it mixes with the emissions coming from the nearby power stations.

But is air pollution really that bad in Buenos Aires?

As you may already know, Buenos Aires is situated on a vast flat plain right next to La Plata River system and as such is frequently buffeted by moderate to strong and gusty winds throughout most of the summer. These winds combined with the flat terrain prevents the accumulation of air pollution over Buenos Aires. In comparison to other large cities (for example, Mexico City) that are surrounded by high mountains that act as havens for smog, Buenos Aires has far less air pollution to worry about.

Do air pollution levels vary in Buenos Aires over the course of the year?

During the warmer months of the year, the city regularly experiences quite a number of windy days and given that Buenos Aires is located over flat terrain with no nearby mountains, there's little chance for air pollution levels to build up.

If you suffer from asthma, it's quite safe for you to walk around the streets of Buenos Aires from late spring to early autumn (fall) since the most of the smog is blown away by the wind. Also, there's far less traffic on the roads during summer school holidays and this of course greatly reduces the air pollution levels.

However, it's during the winter that you need to be particularly careful if you're susceptible to respiratory illnesses, since a combination of meteorological factors (light winds and a strong shallow temperature inversion) occasionally prevents the air pollutants from escaping beyond Greater Buenos Aires.

What is worrying is that in recent years, air pollution during the winter months has been getting worse due to the larger volume of traffic on the roads. This has encouraged many local residents to raise concerns over the risks posed by poor air quality on human health and this has finally spurred the government to address the Buenos Aires air pollution problem by setting up two air quality monitoring stations in areas of the city with the worst air pollution concentrations.

So what are the main causes of air pollution in Buenos Aires?

The city proper has a population of nearly three million residents, all of whom reside in an area that covers just 202.9km².

There's approximately two million vehicles (trucks, buses and cars) driving throughout the city during the peak hour rush period on week days and this combined with the three adjacent thermal power plants is one of the leading causes of air pollution in Buenos Aires.

The two most frequent air pollutants in Buenos Aires city that occurs at moderately high levels is carbon monoxide (CO) and the nitrogen oxides (NO_x = NO + NO₂).

These come from:

1. Area sources
2. Point (stationary) sources

1. The main 'area sources' in Buenos Aires city come from residential, commercial and small industrial combustions as well as road traffic (cars/taxis, trucks and buses) and emissions from the domestic airport (aircraft landing and taking off) located within the city.
   
   
2. The main 'stationary sources' come from the 14 stacks of the three thermal power plants located on the north eastern edge of the city on the banks La Plata River. There is no other large industries within the urban part of Buenos Aires and thus the power plants are the only point sources. These power plants burn natural gas for about 350 days/year and then they must use gas-oil during the coldest days (around 15 days/year). It's this gas-oil combination that is one of the main causes of air pollution in the city and consequently leads to respiratory distress in people who live near the power stations.

The main reason why NO_x vehicle emissions are so high is because most vehicles in Buenos Aires are not installed with catalytic converters. The worst time for these types of emissions is during peak hour traffic times: from 8am-9am and 7pm-9pm.

If you plan to walk around the city during the day in winter, just be aware that it's not overly wise to do so. As you can see from the table above, you will be inhaling high levels of both NO_x and CO which are both detrimental to your health.

However, what you might find interesting about Buenos Aires is the fact that on most nights (not all) the smog quickly disperses after about 10pm and the air remains pollution free until peak hour traffic time the next morning.

Furthermore, nearly all of the Buenos Aires city carbon monoxide levels can by attributed vehicle pollutants. In comparison, power stations produce very little carbon monoxide (0.04%).

I have not mentioned sulfur dioxide (SO₂) emissions since it does not contribute to the causes of air pollution in Buenos Aires. SO₂ emissions are only high in cities that burn coal.

Unusual causes of air pollution in Buenos Aires

There is always abnormal causes of air pollution that take people by surprise. Such an event occurred in Buenos Aires city, when thick smoke from burning pastures moved over the city.

This smoke affected Buenos Aires from the 15th-20th April 2008 and caused severe respiratory symptoms and eye irritation in a large number of people living in Buenos Aires.

Furthermore, there was numerous traffic accidents since visibility levels dropped to less than 100 metres in the smoke. This of course led to the closure of many roads across Buenos Aires.

What made this event quite unusual was the fact that the smoke was blown in towards the city from the north west. Usually the winds blow in from the south east during April and under normal weather conditions, this smoke would not have passed over Buenos Aires.

This event is extremely rare, so please don't think that this will occur when you visit Buenos Aires.

References

1. Berbery EH, Ciappesoni HC and Kalnay E. The smoke episode in Buenos Aires, 15-20 April 2008. Geophysical Research Letters. 2008;35(L21801):doi:10.1029/2008GL035278.
   
   
2. Ostachuk A, Evelson P, Martin S, Davidowski L, Yakisich JS and Tasa t DR. Age-related lung cell response to urban Buenos Aires air particle solution fraction. Environmental Research. 2008;107:170-177.
   
   
3. Reich S, Magallanes J, Dawidowski L, Gómez D, Groselj N and Zupan J. An analysis of secondary pollutants in Buenos Aires City Environmental Monitoring and Assessment. 2006;119:441-457.
   
   
4. Venegas LE and Mazzeo NA. Modelling of urban background pollution in Buenos Aires City (Argentina). Environmental Modelling & Software. 21:577-586.