mexico city is surrounded by mountains. what effect has this had on the air quality in this city?
Check the last sentence in the fifth paragraph.
http://encarta.msn.com/encyclopedia_761569238/mexico_city.html
This site may also help you.
http://visibleearth.nasa.gov/view_rec.php?id=3419
The surrounding mountains in Mexico City have had a significant effect on its air quality. Due to the geographical location of the city, it is located in a basin surrounded by mountains, which creates a natural barrier that traps pollutants, such as smog and particulate matter, within the city.
Here's how you can explain the effect on air quality in Mexico City:
1. Topographical features: The city's location in a basin surrounded by mountains prevents the free flow of air, creating a stagnant air mass. This leads to the accumulation of pollutants in the lower atmosphere.
2. Temperature inversion: Temperature inversion occurs when a layer of warm air traps cooler air near the surface. The mountains surrounding Mexico City contribute to this phenomenon, trapping pollutants closer to the ground and preventing their dispersion into the upper atmosphere.
3. Pollution sources: Mexico City is densely populated, with millions of vehicles on the roads and numerous industrial activities. The combination of pollution sources, geographical features, and temperature inversion exacerbates the air quality issues within the city.
4. Health effects: The poor air quality in Mexico City can have detrimental effects on the health of its residents. Exposure to high levels of pollutants such as ozone, particulate matter, and nitrogen oxides can lead to respiratory problems, eye irritation, exacerbation of existing conditions like asthma, and increased risk of cardiovascular diseases.
5. Mitigation efforts: Recognizing the severity of the air pollution problem, the Mexican government has implemented various measures to improve air quality in the city. These include implementing vehicle emission standards, promoting public transportation, limiting industrial emissions, and implementing programs to reduce agricultural and garbage burning.
By understanding the unique geographical and atmospheric conditions in Mexico City, we can better appreciate how the city's air quality has been affected by its surrounding mountains.