Air pollution from asparagus burning in Caborca, Mexico

Problems

• Agricultural waste burning in Sonora

  The region of Caborca in Sonora, Mexico, is one of the most essential sources of asparagus. Caborca weather is particularly favorable for producing asparagus – hot days, cooler nights, and plenty of sunshine throughout the growing season provide optimal conditions for asparagus growth. These ideal conditions have enabled Caborca’s farmers to establish large-scale production and supply asparagus demand nationally and internationally.
  
  However, in order to stimulate its growth and to obtain more profitable results from the production of the asparagus, once foliage is removed and shredded, it is burned in December when its growth cycle has finished and the plants have dried.
  
  According to one study published by the Commission for Environmental Cooperation (CEC) of the North American Free Trade Agreement, the burning of these residues releases dioxins, listed as persistent bioaccumulative toxicants (PBTs) because they contain chlorine and residues of pesticides absorbed into the tissues of the leaves and stems, as well as being the source of 40% of the CO2, 32% of CO, 20% of suspended particulate matter, and 50% of the polycyclic aromatic hydrocarbons emitted into the atmosphere on a worldwide basis.
  
  These substances contribute to climate change because they contain greenhouse gases and other short-lived contaminants like soot, which cause severe harm to human health, even in very small amounts. For example, effects are seen as reduced sperm count in male infants and children; changes in human thyroid hormone levels, neurological effects from in-utero fetal exposure, low testosterone levels; and reproductive problems in women such as decreased fertility, prolonged menstrual cycles, and early menopause, among others.
  
  In Caborca, the asparagus growers argue that burning is necessary to guarantee the high quality of the product. Nonetheless, Peru and China, the largest producers of asparagus in the world, do not follow this practice. Neither does Spain. In Mexico’s state of Guanajuato, another big asparagus producer, they don’t burn the residue either. It has been shown scientifically that burning is unnecessary in the grower's fields, but they refuse to stop the practice.
  
  The poisoned air drifts across the border into the United States and California’s Imperial Valley, entering the smaller city of Calexico. The pollution here regularly violates U.S. air quality standards, and children in Imperial County are taken to emergency rooms for asthma at one of the highest rates in the state.
  
  The air pollution plagues the Mexicali area isn’t just some of the worst in Mexico. It’s also some of the worst particulate pollution measured anywhere in the Americas.
  
  The toll of lives lost is ghastly. Mexican health records show at least 78 people died of asthma and 903 died of chronic obstructive pulmonary disease in the Mexicali area between 2010 and 2016. Officials in Baja, California, have estimated that pollution causes about 300 premature deaths annually in Mexicali.
  
  Researchers have found that Mexicali’s pollution is among the deadliest in Mexico. In a 2013 study, the independent Mexican Institute for Competitiveness examined data for 34 of the country’s biggest cities. It estimated Mexicali had the highest rates of premature deaths and hospitalizations due to air pollution.
  
  With the asparagus industry, what Caborca gets in return is environmental contamination since 95% of the economic benefits are bound for the United States. There is a need to prohibit the burning of asparagus stalks for the well-being of the local population whose health is at constant risk, not to mention the high incidence of cancer that has exploded in the region in recent years, as well as asthma and acute respiratory illnesses.