FEATURE - Mexico City breathes easier as air quality improves
Date: 25-Sep-01
Country: MEXICO
Author: Fiona Ortiz
Despite the reputation, the air quality in the metropolitan area has actually improved in recent years. And the city is planning to get tougher, cracking down on exhaust-spewing trucks that have skirted strict rules imposed on cars and lowering the bar for declaring pollution emergencies.
The Metropolitan Environmental Commission, an agency drawn from different levels of government for one of the biggest cities in the world, plans to unveil this month a new 10-year air quality plan, replacing a 5-year program that expired in 2000.
Mexico City Environment Secretary Claudia Sheinbaum said the aim of the 2001-10 plan is to bring down stubbornly high levels of ozone and fine particulate air pollution, by toughening standards and calling more pollution emergencies.
When pollution alerts are called, higher-emission cars are banned from the roads, which over the long term motivates people to get cleaner vehicles.
"We still are not doing as well as we could. We still have very high levels of ozone. Ninety percent of days we are higher than international standards for ozone levels," said Sheinbaum, a university researcher on energy issues.
The ozone layer in the upper atmosphere protects the earth from harmful ultraviolet radiation, but ground-level ozone, formed when pollutants from vehicles and industry are baked by the sun, is a key component of smog and is unhealthy for lungs.
Other key elements of the plan are to retire old trucks, limit cargo circulation hours, use more natural gas in public buses, give taxi drivers incentives to buy newer cars, make fuel efficiency standards stricter, and introduce hybrid gas-electric cars and buses when the proper fuel is available.
Sheinbaum said the new rules have been delayed because of difficulties coordinating the government of the federal district of Mexico City proper, the Mexico State government that administers the sprawling working-class neighborhoods that ring the city, and the national government, but that all agree tougher measures are needed.
STUBBORNLY HIGH OZONE
Pollution here is so thick the World Resources Institute in 1999 named Mexico City as the unhealthiest in the world for small children due to combined high levels of various pollutants measured from 1993-95.
Emissions from vehicles cause some 70 percent of pollution in the urban area, which spans 1,500 square miles (4,000 square km).
A string of measures adopted in the early 1990s and intensified under the 1995-2000 Air Quality Program took aim at curbing car emissions, including rules that keep older and more-polluting cars off the street one day a week, introduction of catalytic converters and lower sulfur levels in gasoline.
The good news is the measures have brought down levels of lead, sulfur dioxide, carbon monoxide and nitrogen dioxide to lower than international safety norms almost every day.
The clearer air in recent years is also due to favorable weather conditions including fewer thermal inversion layers and winds that have kept pollution from being trapped in this valley 7,350 feet (2240 meters) above sea level, experts said.
The difference over recent years is palpable. In the center of town, lungs strain and eyes tear less, and on fewer days. In the rainy season, from May to November, smog-free clear views across the spectacular Valley of Mexico seem more common.
The bad news is ozone and levels of total suspended particulates are still way too high. Fine particle pollution levels exceed international safety levels some 13 percent of days, Sheinbaum said. Tiny pollution particles penetrate deeply into the lung's air sacs and are associated with various health problems.
NEW BAR FOR EMERGENCIES
The problem is that while ozone and fine particle pollution levels in Mexico City hover well above what is considered dangerous by international standards, they are still below the emergency levels established here 6 years ago.
When the city declares pollution emerg
