Air Quality slider — 25 July 2014

The University of Santiago (USACH) Department of Physics, has completed a report on the sources of air pollution in the Santiago metropolitan region.  The report was commission by the Ministry of the Environment. Dr. Ernesto Gramsch of The University of Santiago led the project.

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The report is an inventory of airborne contaminants from August to September 2012.  The data was collected by fixed and mobile monitors and loaded into software called Airviro.  This system uses Danish, MATCH, and Gauss sophisticated models that take into consideration the weather, the height of physical structures, light diffusion, and input from fixed and mobile chemical-level monitors to give a detailed picture of sources of contamination in Santiago, down to the street level.  The Airviro user can select an area of the map and get the sources of pollution for any particular day.  The system and report are so detailed that it has even inventories of such difficult-to-measure and smaller-scale items as the emissions of solvents from business who spray paint.

This model will be used as input for the detailed Plan for the Decontamination of Santiago to be published in 2016.  An intermediate proposal for the short term has just been released to the Ministry of the Environment from the Mario Molina Center in Mexico City. That proposal was headed up by Dr. Mario Molina, who is a Nobel Prize winner in chemistry.  Presumably he used Dr. Gramsch’s inventory as input to his recommendations.

We will publish a review of that plan shortly, but suffice it to say that it goes after the number one problem in Santiago, which is the use of wood for heating homes, plus the proposal makes incremental improvements to diesel-power buses, auto, and trucks by phasing out the worst polluters.  The plan also proposes to move public transportation to electric vehicles starting with a pilot program of 100 electric vehicles.  (Some of these vehicles could come from the new BYD electric bus and battery factory in Brazil, which we wrote about yesterday. The city of Bogotá, Colombia has already ordered 40 BYD electric vehicles, plus they ordered 800 diesel-electric hybrid vehicles from Volvo, to deal with its substantial air pollution problem there. The Minister of Transportation had stated a preference for all-electric vehicles over hybrid ones, according to other media reports.)

Now, here are some highlights of the Santiago inventory.  The report covers all the major pollutants, like carbon monoxide, nitrogen dioxide, and more.  At SPR, we are focused mainly on PM2.5, since it is the most visible problem in Santiago, as you can see this smog hanging over the city as a brown haze every day in winter.

PM2.5 is the most dangerous form of particulate matter, as it can penetrate deeply in the lungs.  It is responsible for the death of more than 4,000 people per year in Santiago.  The Chilean standard for PM2.5 pollution is much lower than the current EPA standard.  Also the Santiago Euro III standard for vehicle emissions, in particular for buses and heavy vehicles, is 14 years older than the Euro V and Euro VI standards.

At SPR, we maintain a real-time registry of PM2.5 pollution showing the absolute number and its rating on both the Chilean and EPA scale here. The data comes from the Ministry of the Environment. We have overlaid the EPA scale on top of that.

The other pollutants in the report are certainly crucial to reduce for health reasons.  Among these are carbon monoxide (which is fatal at high doses) and ozone (which causes respiratory problems).  But we do not have the resources here to study all of that at this at SPR.

For example, we looked at ozone readings in the Santiago area, but the American EPA told us that the results from the Chilean Ministry of Environment monitoring network cannot be translated to their air quality index (AQI).  That suggests there is something wrong with the numbers coming from the Chilean ozone monitoring stations.

The Chilean monitors consistently show that the ozone levels in Santiago are good.  But the USACH report says that nitrogen dioxide levels coming from vehicles in Santiago are high.  When the sun shines on nitrogen dioxide that produces ground-level ozone.  So the question about ozone levels in Santiago remains an open one.

Now, here are some highlights from the USACH report.

Overall, these are the sources of PM 2.5 pollution in Santiago. As you can see the Transantiago buses and other vehicles are responsible for 44% of this pollution. Wood-burning stoves are responsible for 22%. Where we list “other” sources, keep in mind that this report covers a large area including distant rural regions on the other side of the mountains.  For example, this report covers the Caletones copper smelter, plus farmers burning their fields, both of which, of course, are not in the city proper.

 PM 2.5 emissions by source
Transantiago + major highways 8%
other transportation 36%
residential wood-burning systems 22%
other (industrial, agricultural burning, outdoor grills, etc.) 33%

Here are the tons of MP2.5 pollution emitted by wood-burning stoves for selected communas (Santiago is divided into smaller cities called “communas,” each of which has its own mayor.).  The USACH inventory covers the entire metropolitan region, including rural areas distant from the city, so we don’t list small towns, like Curacaví, because the list is long and Curacaví is 53 km from downtown Santiago on the other side of a major mountain range. Instead, here we list the major neighborhoods inside Santiago.  We don’t list Providencia either, a wealthy area in Santiago, because all the readings there said “0,” suggesting the monitoring stations in that area were not working.

As you can see, Las Condes, is a major contributor to this pollution. Las Condes is another upper-class neighborhood.  So burning wood is not just a problem in the poorer neighborhoods to the west, although the report says that the majority of the pollution from wood-burning fireplaces comes from the western side of Santiago, it also says that Santiago residents across the whole of the city burn wood for heating. Regular fireplaces are banned in Santiago, but so-called double-combustion and indoor wood stoves are not.  As you can see, the double-combustion systems are not clean burning at all.

MP(ton) wood burning stove (salamandra) other wood burning Double combustion
El Bosque 1,0 2,0 17,1
Huechuraba 2,3 1,2 19,8
Independencia 0,0 0,4 1,9
Isla de Maipo 47,5 3,1 18,5
La Cisterna 1,2 1,3 10,3
La Florida 0,0 1,8 30,1
La Pintana 0,2 0,3 4,4
La Reina 0,0 0,8 11,7
Las Condes 2,5 2,6 41,9
Lo Barnechea 7,5 0,0 12,6
Maipú 41,5 13,2 17,1
Ñuñoa 0,0 0,3 5,9
Peñaflor 23,8 2,5 30,4
Peñalolén 0,7 2,2 11,4
Pudahuel 19,2 4,4 5,7
Puente Alto 0,0 12,8 71,7
Quinta Normal 5,4 4,5 1,4
Recoleta 0,5 1,0 7,7
San Bernardo 0,6 0,7 11,5
Santiago 5,0 1,0 10,7

This next graphic says much about the overall sources of PM2.5 pollution and the areas they affect. The graphic of annual levels paints quite a different picture than the hourly readings shown on the Ministry of the Environment website.

In Santiago, the PM2.5 pollution is worst in the winter, because cold air above traps warmer air below between the mountains that surround Santiago.  That is called thermal inversion. Plus there is less wind in winter and it only rains here maybe 4 to 6 times per year.  Rain cleans the air, at least for a day or two.

The air quality alerts in the city are based on hourly measurements.  For example, right now as we write this (25 July 2014) Cerro Navia is under an air quality alert for PM2.5 on the Chilean scale.  The latest hourly reading there was 84 microns per cubic meter.

An annual estimate would be much lower, since it includes the whole year, meaning the spring, summer, and fall, when the air is much cleaner because there is no more thermal inversion.

Taking together all the sources of PM2.5 emissions from the entire Santiago region, the graph below paints a much different picture than that given by the hourly air sampling network of the Ministry of the Environment.

The graphic below shows that the worst emissions are concentrated along the Alameda-Providencia corridor, which is of course where most of the traffic is and most of the office buildings are located.  There is not even an air quality monitoring station in La Providencia nor in downtown Santiago. The closest is in Parque O’Higgins.

The colors in red indicate PM2.5 >=20 µg/m3.  The annual EPA standard is 12 µg/m3. Anything that is yellow is above the EPA recommendation.



You can see the color coded scale a little better here.  Sorry, we do not have the larger graphic at any higher resolution, yet.


Anyway, there is a very brief overview of Dr. Gramsch’s very detailed report.  We will be drawing on it in detail as we continue to write about air quality in Santiago.




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