In Mexico City, they say, the air is so bad that birds fall out of the sky.
Ranked most polluted of the world's capital cities in 1992 by the UN, and the fifth most polluted capital city in the world in 2007, Mexico City is home to 22 million people, most of them at or below poverty level.
As the world's largest city, with 570 square miles and a population density of more than 30,000 people per square mile, Mexico City once teetered on the edge of becoming an apocalyptic vision of mankind's worst nightmare - total ecological collapse.
The city is built on a 7,000-foot plateau surrounded by mountains. This has the effect of creating frequent thermal inversions, also known as the ‘bowl effect', which exacerbate air pollution by trapping layers of pollutants under a layer of warmer air.
But things are changing. To understand how much, you have to understand the air quality index (AQI), an internationally standardized formula which measures ground-level ozone and particulates. According to the AQI, 0 to 100 is satisfactory, 100 to 200 is not satisfactory, over 200 is bad, and over 300 is lethal.
In the mid-1990s, Mexico City's AQI was over 100 about 90 percent of the time. In 1996, it topped 394 for five consecutive days. During that time, more than 300 people died. By January of 2001, however, there had not been a smog alert for 15 months and now, in 2009, Mexico City has dropped to number 30 on the list of the world's most polluted capital cities in terms of emissions and particulates.
A recent Associated Press article ascribes the pollution to vehicles, and its reduction to a group of government workers who call themselves the ‘ecoguardia' or eco-guard. These ecological watchdogs go around checking tailpipes for emissions and tagging cars that clearly violate pollution standards. The penalty for visibly noxious emissions is either a $100 fine or the loss of the car's license plate, which effectively takes the offending vehicle off the streets.
Unfortunately, the other (and highly significant) cause of Mexico City's bad air is unregulated factories on the rim of the city. This is an issue which Mexico City's Democratic Revolution Party (PRD), headed by Mayor Andrés Manuel López Obrador, either doesn't know how to address or doesn't have the cojones to take on. Many of the factories are owned or run by multinational corporations. Regulating vehicles, or appearing to, is less confrontational and does less damage to Mexico City's economic infrastructure - not to mention the coffers of said political party.
One PRD plan, dubbed "hoy no circular" (today your car does not drive), reduced the number of cars on city streets by instituting no-driving days according to the color of the license plate. This one-day-a-week restriction had little effect because only the wealthiest of Mexico City's inhabitants have cars, and those half-million individuals frequently own two or more cars. When a no-drive, yellow-plate day came around, they simply switched to another vehicle.
This is not to denigrate the efforts of the Mexico City's ecoguardia, who - like Gabriela Escalante - patrol the streets of the city looking for violators. This small but determined force of men and women has is to be congratulated for its efforts, which have become a model for improving urban air quality in other large cities like Hong Kong.
In spite of these efforts, the city's cloud of ozone pollution persists. This layer - a secondary manifestation of pollutants like nitrogen oxides (NOx) from burning fossil fuels and volatile organic compounds (VOCs) from industrial processes - hovers close to the ground, plaguing the lungs, eyes and noses of Mexico City's inhabitants. High-altitude sunshine further exacerbates the process, transforming the chemicals into a lethal haze that settles, especially in winter, like a smudge of burning rodent fur over this teeming metropolis. On the worst days, cyclists still wear masks, reminding world travelers of the recent Olympics in Beijing.
Mexico City plans to spend $3 billion by 2012 to expand public transit and further slash emissions. Data from AQI monitoring stations confirm that lead, sulfur dioxide, carbon monoxide and ozone levels are all appreciably below 1991 levels. In spite of that, ozone levels still exceed recommendations more than half the time.
According to Mexican-born Dr. Mario Molina, the 1995 Nobel Prize-winning chemistry professor at MIT (Massachusetts Institute of Technology) who was recently appointed president-elect Barack Obama's transition team advisor on environmental issues:
"There has been a large improvement, and it's important to show it could be done. But there's still a long way to go to get really satisfactory air."
It doesn't help that the government still subsidizes gasoline, even though state-run oil company Pemex has failed to introduce low-sulfur fuel, or that most trucks and buses are exempt from emissions testing. Nor the situation likely to improve now that NAFTA regulations have gone into effect, allowing a flood of used cars to cross the border from the U.S.
From north of the border, we can only hope Gabriela Escalante's small army is staunch, persistent and indefatigable, and that the PRD finds the courage to take on the multinationals.