The Tijuana river is a watercourse that crosses Mexico and flows into the ocean reaching the South Bay region, in the County of San Diego, California: here some beaches have remained closed for almost 1,300 consecutive days due to the contamination of the water due to the presence of industrial waste and untreated waste water.
For some time, however, the residents of the area have complained of health problems – such as nose irritation, throat and eyes, respiratory and headache problems – connected to the air quality and bad smells from the river: a study published on Science Confirm that the tijuana does not only pollute the water, but also the air, emitting large quantities of sulphide acid, a toxic gas typical of sewers with a characteristic smell of rotten eggs.
The study. Air analysis were taken to South Bay starting from September 2024 for three weeks in a very turbulent stretch of the river from which particularly strong smells came. The tools revealed peaks of sulphide acid concentrations of 4,500 parts per billion (PPB) for at least one minute, and up to an average of 2,100 ppb for an hour.
To have a comparison term, the California Office of Environmental Health Hazart Assessment establishes a limit of 7.3 ppb for a chronic exposure to toxic gas. The highest levels were recorded at night, when the wind calms down. “We have shown for the first time that a poor water quality can greatly worsen the quality of the air, exposing entire toxic gas and other polluting communities,” comments Kimberly Prather, research coordinator.
What solutions? To solve the problem in the short term, researchers advise to increase the use of air purifiers, provided free of charge by San Diego County to residents to allow them to breathe a cleaner air at night.
On the long term, the government must solve the problem at the root, enhancing the infrastructure of water treatment on both sides of the border (Mexican and US) and updating the policies that regulate river management.
