Last week fog crept over the Tijuana Estuary in Imperial Beach, oozing a pungent rotten-egg smell, as hydrogen sulfide bubbled up from the polluted Tijuana River. … Later that day, Thursday, March 19, air pollution monitoring data showed hydrogen sulfide levels at 500 parts per billion, more than 15 times the California state standard of 30 parts per billion. … When raw sewage enters the river in Mexico because of wastewater system failures or spills, the health impacts are felt across the border. Imperial Beach residents describe asthma, migraines, rashes, nausea, eye irritation, dizziness and brain fog when the sickening smell of hydrogen sulfide wafts off the water. 

Other Tijuana River news:

• KPBS (San Diego): Spikes in sewer gas levels in Tijuana River Valley highlight gap in a public alert system
• Times of San Diego: Sewage discharge causes county to close dog area in Ocean Beach