Understanding Pollen Pollution and Impact on Health in Mexico City

Experts have revealed that only certain types of pollen found in the atmosphere of Mexico City (CDMX) are allergenic, meaning they contain specific proteins that can trigger symptoms in susceptible individuals. Pollinosis, or allergic disease, affects between 15 and 25 percent of the population in some regions, including the capital.

However, not all pollen grains cause allergies. During a recent press conference on "Pollen Pollution: How is it affecting us?", María del Carmen Calderón Ezquerro, the coordinator of the Mexican Aerobiology Network (REMA), based at the Institute of Atmospheric Sciences and Climate Change (ICAyCC) of the UNAM, explained that this winter, there has been an increase in the presence of pollen in Mexico City compared to last year.

For example, in the Chapultepec area, pollen levels have increased by almost 100 percent, and in Coyoacán, they have increased by 40 percent. However, these grains are not concentrated in areas with more vegetation, as the wind carries them from one location to another, not just within the city but also in neighboring states.

The most common pollen types include those from ash trees, thuja trees, junipers, oaks, various types of pines, and eucalyptus. The ash tree, which makes up 50 to 55 percent of the pollen in the air, is the most likely to cause allergies. However, there are annual and biannual tree species with higher concentrations, such as oaks, which start to diminish in May, while others, such as pastures, emerge.

Calderón Ezquerro also emphasized that tree pollens, like ash trees, tend to increase their concentration between noon and five or six o'clock in the afternoon, while decreasing slightly in the morning and at night, depending on the type of pollen. Those responsible for reforestation in the capital of the Mexican Republic consider allergenicity among the factors when developing their tasks. "It is not a matter of removing ash or oak trees, but of changing some species for others," she said.

She also noted that pollen concentration is not yet included in the air quality criteria, and the Secretariat of the Environment of the capital city should consider this parameter in the warnings and indexes provided to citizens. REMA carries out monitoring to show the main pollen types and their concentration levels present in the air during the year, through five stations located in Mexico City and its metropolitan area, as well as one in the states of Sonora and Sinaloa.

Allergy Symptoms and Treatment

Guillermo Guidos, an allergist affiliated with REMA, explains that pollen can have a direct impact on people's quality of life. This condition, formerly known as "hay fever" or "spring allergy", is called pollinosis and is multifactorial.

The main symptoms of pollinosis include conjunctivitis, which is characterized by red, itchy, and inflamed eyes, as well as respiratory issues such as an itchy nose, frequent sneezing, nasal secretion or obstruction, and for some individuals, asthma, which may cause shortness of breath, choking sensation, or wheezing chest.

Although patients may experience more symptoms during the winter and spring months, it's important to note that pollen is present throughout the year, even if it's from different species. REMA is a vital tool that helps identify which substances are in the environment and their impact on health. By analyzing allergenic grains, physicians can study the effectiveness of treatments and provide personalized recommendations to patients.

Guidos notes that allergies typically develop during childhood and adolescence, but they can occur at any point in life. For those with sensitivities, it's recommended to keep windows closed during the day and use protective gear such as high-efficiency masks that can trap pollen particles.

If you've already been diagnosed with pollinosis, it's important to follow the treatment plan prescribed by a certified allergist. Guillermo Guidos emphasizes that treatment and recommendations should be tailored to the individual.

Pollen Transport by Wind

According to Benjamín Martínez López, a researcher from the Climate Change and Solar Radiation Group at ICAyCC, wind plays a crucial role in transporting pollen from point sources in specific regions of the Valley of Mexico. Generally, the prevailing wind circulation in this area moves from the highlands to the lowlands in the afternoon-evening, while during midday, the air moves from lower altitudes to the mountains.

To understand how pollen moves from specific point sources, numerical models are essential to simulate atmospheric conditions, including wind, temperature, and precipitation. This information is crucial for the public.

Martínez López added that rainfall positively "washes" the atmosphere, but the absence of rain may impact the development cycle of trees, grasses, and plants.

Long-term variations in pollen presence can occur due to atmospheric or climatic events, as was the case during the winter of 2009-2010 when its presence decreased or increased.

Martínez López acknowledged that predicting drought conditions in the country for the upcoming months is complicated. Thus, there is a need for an accurate seasonal forecast system to help predict pollen presence on longer timescales.