It is interesting to note that Mexico City’s metropolitan area experienced similar conditions in the early 1990s, and was infamous for its high air pollution levels. Fast forward to today, and the situation is vastly different. Mexico City has set an example for Indian cities like Delhi.
Today, most cities are suffering from air pollution and are urged to take actionable steps for cleaner air, and to minimize its negative impact on health, ecosystems, vegetation, climate change, water and energy. As concentrated areas of population, cities have the potential to leapfrog the process of managing and controlling air pollution, by learning from other cities that have successfully done so.
How did Mexico City achieve results?
In Mexico City, air quality improved as a result of a wide set of measures to reduce emissions from different sources including transport, services, and industries. Over the last three decades, these sectors have come together to work in a cohesive way.
According to a recent study by experts from the Harvard School of Health and Mexican researchers, air quality improvements from 1990 to 2015 in PM2.5 and ozone helped prevent 22,500 premature deaths and increased the life span of Mexico City residents by almost three years. In fact, data generated by a robust air quality monitoring system has shown reductions in all pollutants.
In the case of some pollutants like ground-level ozone and PM2.5, the levels should continue to reduce further. In 2017, Mexico City’s average concentration of PM2.5 was 23 micrograms per cubic meter (g/m3), which indicates that current efforts should be maintained until 12 g/m3 – the Mexican air quality annual standard – is achieved.
Identifying the sources of air pollutants, what they do, and understanding how these pollutants interact in the atmosphere in a specific city is among the key elements for improving air quality.
Use of data to monitor and control air pollution
In Mexico City, data and knowledge have been key to designing, tracking and evaluating an air quality management strategy through robust monitoring, emissions inventories, and studies in collaboration with leaders in the scientific community. Data and knowledge have been used by decision-makers to prioritize, monitor, and evaluate the effectiveness of actions implemented, while civil organizations have used them to evaluate and demand immediate steps to improve air quality.
Communicating the dangers
An ‘Atmospheric Contingency Plan’ was implemented three decades ago and has evolved. The plan includes alerting and even declaring an emergency when pollutant levels touch the brink in one of the 34 automatic air quality monitoring stations. The action that different sectors need to enforce is communicated through press releases, announcements, and reports.
Some of these steps are, more restrictions on vehicles that are high emitters, reducing operational capacity of industries and limiting construction, among others. The impact on health is communicated specifically to those most vulnerable, to spread awareness and reduce exposure to high levels of pollutants.
Rethinking Mass Public Transit
Actions to reduce emissions from transport have been one of the most effective ways to reduce pollutants like carbon monoxide, sulfur monoxide and PM2.5 in Mexico City. These include the elimination of leaded gasoline, use of ultra-low sulfur content gasoline and diesel, a catalytic converter, inspection of exhaust emissions every six months, restricting most polluting vehicles and heavy duty diesel vehicles.
A big role was played by the aggressive transformation of the public transport network comprising of 12 subway lines, an electric train, electric buses, and seven Bus Rapid Transit (BRT) lines. Bike roads and a public bicycle system were implemented. Over the years, all these actions resulted in better access to public transportation, and improved air quality was achieved.
To reduce industrial emissions, the closing of a refinery had an immediate impact on reducing levels of sulfur dioxide and particulate matter as well as other air toxins. Voluntary emission was reduced with the help of pollution control devices. Local regulations were published, including emission limits for small and medium-sized boilers and even crematories, to keep in check sulfur and nitrogen oxides, particulate matters and volatile organic compounds emissions.
Addressing the Biomass burning challenge
In Mexico, waste burning is prohibited by federal law. However, backyard waste burning still takes place; in addition to awareness campaigns, Mexico City has implemented a city-wide program to separate, collect, and treat urban waste.
Communicating air quality status
A mobile application, a dedicated phone line, and a user-friendly web page have been developed to inform the society of the air quality situation on an hourly basis as well as communicating the air quality forecast 24 hours in advance.
Cleaning the air is not a one-time step since cities are continuously changing and adverse conditions resulting from climate change are worsening air pollution levels. Mexico City also has a long road ahead, and can learn from other cities that have reduced air pollution and implemented mitigation strategies. Last May, Mexico City experienced one of the worst episodes of high PM2.5 levels that led to an atmospheric contingency. Besides daily pollutants, forest fires, agricultural burning and atmospheric stability were some of the causes.
Mexico City could learn from other cities that are experiencing high levels of PM2.5. How cities like Delhi and Beijing have responded can perhaps help Mexico City update its current emergency program.
(Beatriz Cardenas is Air Quality Manager, WRI Mexico. She is an expert in air pollution, with experience in both science and policy, and works on developing strategies and programs to accelerate the path to a cleaner air in Mexico. She has worked as the General Director of Air Quality Management in Mexico City’s Secretary of Environment in 2017-18.)
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