It is a normal day when most Mexicans leave their homes to go to work or school, on the way they hear some birds, dogs barking, and car noises such as engines or horns; but at the same time you see garbage, excrement from dogs and other animals, smoke coming from cars or public transport. The only thing that cannot be observed is what Mexicans breathe in Mexico City.
Recently, the Environmental Commission of the Megalopolis (CAMe) has alerted the population when any of the Environmental Contingency Phases is activated, mainly due to ozone, and the double program Hoy no Circula is usually implemented. It also mentions that the objective of this measure is to reduce the population’s exposure to polluted air and the risk to their health, but what does it mean?
From the fecal matter of dogs, cats, pigeons, and even people; vehicle emissions, both private and public transport; industrial emissions; combustion of forest fires; evaporated fuel, cigarette smoke; garbage, which at the same time generates spores, viruses, and fungi. Everything we throw on the ground and in the air, we are going to breathe.
According to the biologist Gabriela Gutiérrez Olguín, talking about air pollution is not only saying “it hurts to see the smoke coming out of the cars” but it is causing suffering from migraines, fatigue, or irritability since there have been studies that talk about how pollution affects the biochemical processes of our brain.
Gutiérrez Olguín stated that until a few years ago, data from the World Health Organization (WHO) indicated that at least 7 million people die prematurely each year due to air pollution. There is also data that some of the particles we breathe can cause obesity since they lodge in the fatty part of our body; even some of the contaminants are transmitted through breast milk.
The biologist expressed her concern about the lack of reports on how illnesses associated with contamination have increased, resulting in a burden on the health system. “No one is calculating what the burden is on the health sector when you are hit by these chronic diseases like cancer or COPD (Chronic Obstructive Pulmonary Disease) that are lifelong,” she said.
She considers that there is a great need for these types of studies to be funded and commented: “You cannot have a productive population if, apart from the long journeys of public transport, you are getting sick.”
Dr. Elizabeth Vera Rangel, senior researcher at the Institute of Atmospheric Sciences and Climate Change of the National Autonomous University of Mexico (UNAM), explained that before it was believed that pollution only affected the respiratory because the particles are inhaled; however, now there are many studies where it has been seen that air pollution can be a precursor to cancer, heart attacks, arterial obstructions, hypertension, and she agrees with the biologist Gabriela that obesity has been associated with this problem.
She collaborated in an investigation on the follow-up of pregnant women exposed to high concentrations of pollutants, what was seen was that their babies had a lower weight than the average.
“Before they told us that only the respiratory tract was affected because you inhale large particles such as PM10, which can be retained with the hairs that we have in our nose, such as dust and some bacteria, fungi, etc; but the others that are combustion like PM2.5 if they pass directly to our lungs and smaller particles reach the alveoli (where the exchange of gases between the blood and the inspired air takes place) this causes many diseases”, she indicated.
The researcher commented that the quality of the air will depend on the season of the year in question, what has been noticed is that in the dry-hot season, which runs from March to May, as well as the dry-cold season, from November to February, is when the concentrations of polluting particles in the atmosphere increase.
The CAMe has indicated in various bulletins that the highest radiation of the year that occurs in the hot months, plus the lack of rain and a weak wind are factors that contribute to environmental contingencies. Vera Rangel added that it is a time when ozone concentrations increase and in other months there is not so many problems.
Carbon monoxide, nitrogen oxide, and sulfur dioxide are associated with vehicle emissions; however, the main pollutant is the concentration of ozone, although this is not emitted directly. “It is formed from what are called precursors, that is, nitrogen oxides, all vehicle exhaust emits them and also volatile organic compounds, there are a variety of these compounds,” said Dr. Elizabeth.
Although it is believed that industries and vehicles are solely to blame, Vera Rangel pointed out that there are many factors that contribute to poor air quality, and we are all part of that problem. In the dry season, many forest fires occur, these generate a great deal of particle pollution as they travel into the atmosphere and have an impact on Mexico City. These are caused by some human carelessness or actions such as cigarette butts that remain lit and even the burning of garbage that is still very present in the City, especially in rural areas.
The doctor commented that despite the combustion generated by private and public vehicles, any activity, no matter how small, will contribute to poor air quality. For example, people who smoke, or use anything that contains a solvent, such as in some trades such as screen printing; but do not minimize things as simple as acetone to remove nail polish, light a candle or incense also contribute to the problem.
Technologies now used by transport in the capital are cleaner, they are called euro 6 and euro 7, they require better fuel and that greatly reduces air pollution.
The Hoy no circular program, in her opinion, has managed to reduce pollutants. It is a sum of factors: the change in public transport technology, vehicle maintenance, and stopping driving when there is an environmental contingency has contributed to reducing pollution.
“In the strictest COVID stage, we were able to observe that the concentrations of pollutants such as carbon monoxide and nitrogen oxide were reduced because we did not go out. However, the particles did not decrease as much because even though we were in the hardest stage of COVID, there were a lot of wildfires .”
Regarding the refinery in Tula, Hidalgo, the researcher commented that the emissions that are emitted travel to Mexico City and impact air quality. Biologist Gutiérrez mentioned that some of the sanitary landfills are within the City, such as the one in Tlalpan, and next to it there is a school, so all the emissions that come out of there are breathed by the children.
It is recommended to put gasoline in the morning or at night, this prevents the fuel from evaporating and emitting that unpleasant smell of gasoline; deciding not to smoke contributes to not generating so many lethal compounds that it contains. Use the car less and also tune it up when appropriate; avoiding the burning of fireworks should already be a priority.
Researcher Elizabeth highlighted that at the worst moment of COVID, common diseases such as throat infections decreased because the use of face masks helps stop certain particles, but not all. Both specialists agree that face masks can stop certain particles. But there is PM2.5, which Vera Rangel explained can fit in a hair, which is 70 micrometers per cubic meter, these particles are 2.5 micrometers per cubic meter, so only a really closed filter could help considerably.
People in Mexico City think that the air smells like: “burnt”, “garbage”, “food”, “smoke”, “dirty leaves”, “diesel”, “spout”, “soot”, “smog”, “dust”, “grease”, “drainage”, among others. To this Vega Rangel added that we are all part of the problem and we are also part of the solution since everyone thinks that the industry pollutes too much, but we cannot forget that it does what we ask for and we have to be aware of what we want to consume.