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Air Quality Declines in San José

Contaminant levels in San José’s air are on the rise and an increase in the number of vehicles, particularly those powered by diesel fuel, is to blame, according to a study released Tuesday by Universidad Nacional (UNA).


The ¢15 million-per-year study, jointly funded by UNA and the San José Municipality and carried out by UNA researchers, measured changes in contaminate levels from the periods between 2003-2004 and 2004-2005.


Using electronic sensors placed on light posts in 14 of the most congested areas in downtown San José, researchers measured levels of nitrates, sulfates and particulate material (mostly vehicle exhaust), explained Jorge Herrera, coordinator of UNA’s Environmental Analysis Laboratory. Overall, contaminant levels in these 14 points rose from one year to the next.


For example, nitrogen dioxide levels rose anywhere from 3% to 20% in 12 of the 14 points. Four of these points showed nitrogen dioxide levels exceeding acceptable levels established by the World Health Organization: Hospital San Juan de Dios, the Metropolitan Cathedral,Ave. 10 and Paseo de los Estudiantes.


In 2004, another UNA air-quality study, which used white sheets against screens to gauge air pollution, also found contamination levels exceeding health limits at some of these same points (TT, Nov. 5, 2004). Costa Rica does not have its own standards for nitrates and sulfates in the air, Herrera said, and one of the study’s goals is to help authorities establish them. Breathing heavily contaminated air can cause dizziness, nausea and headaches, particularly in people who suffer from asthma or other respiratory problems.


The use of contaminant-producing diesel fuel surpassed that of gasoline last year as consumers sought to save money, explained UNA Rector Olman Segura. This, along with more imported, used cars on the roads and lack of a centralized bus system, which makes for congestion in the city center and multiple buses along the same routes, are to blame for declining air quality, he said.


San José Vice Mayor Maureen Clarke said the municipality asked UNA to carry out the study.


“We wanted to have statistics to be able to intervene,” Clarke said. A tree-planting project, monitoring of birds and butterflies and the construction of a botanical garden are part of the Municipality’s plans to beautify San José and improve its environment, Clarke said.


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