Nancy and Bryan Lara, ages 10 and 8, knew something was wrong when they saw a tractor surrounded by white clouds near their school bus stop in Caruthers.
"I know that clouds are not on the ground, they're in the sky," Bryan said.
The children hid behind a row of grapevines, but they could taste the noxious blend of liquid sulfur, gibberellic acid, insecticide and fertilizer as the rig rolled past them, billowing out its chemical cargo.
Moments earlier, the mist had enveloped 17-year-old Carina at another stop about two blocks away.
"I felt it. It was wet. I was wet," said Carina, who asked that her last name not be used.
School bus driver Crystal Wells drove up in time to see Nancy and Bryan running for cover. She pulled her bus to the side of the road to avoid exposure. Her decision kept 50 children from being exposed.
The May 14 incident was the third case in seven months in which San Joaquin Valley children were exposed to pesticides while at stops or on school buses. Despite regulations and laws in place to protect children, including programs to encourage growers to be aware of school bus routes, authorities estimate that school buses are still drifted on once or twice a year in Fresno County alone.
Though relatively rare, such incidents remain a reminder of the daily hazards of life in California's agricultural hub.
"Children are almost like a different species in terms of how they metabolize," said Nina Holland, the lead researcher of a UC Berkeley study that found children are more susceptible than adults to organophosphate pesticides. "We are talking about a very significant difference. We really need to look at protecting children."
Kryocide, the chemical that the children were sprayed with, is not an organophosphate. It is "slightly toxic if inhaled" and can damage a person's kidneys and bones if they are repeatedly exposed to it, according to a manufacturer's information sheet.
But what happened next shows how pesticide exposure can cause more than physical harm.
The bus driver picked up the three children, called her supervisor and drove them to Caruthers High School, where they were met by firefighters, medics and investigators. Soon, the three began to suffer headaches, nausea, itchiness and breathing difficulties.
Erika Lara arrived to find her two children hooked up to oxygen.
"I cried because they had oxygen on," Lara said. "I wasn't expecting that."
The mother's first instinct was to hug her children. The chemicals on their clothing made her arm red and itchy, she said.
All three children were escorted to showers and told to change into clean clothes. But investigators never collected the contaminated clothing, saying the children's father refused to give them the samples. Francisco Lara said he was never asked for the clothes.
After showering, the children were taken to the hospital. They were released by late afternoon.
The event has left a strong impression on the Lara children.
"They saw my brother and me and they never stopped the tractor," Nancy said. "They don't care if they get on us and they don't have to pay the cost."
Such feelings are typical in cases of pesticide exposure, according to Gina Solomon, a physician and scientist with the Natural Resources Defense Council.
"Sometimes the anger and fear and anxiety of being exposed to a potentially toxic chemical against your will is as bad as the effects of the chemical or even worse," Solomon said.
When asked if he felt angry, Bryan Lara nodded. "I wanted to beat them up," he said.
According to a sheriff's report, the man Fresno County Sheriff's officials identified as the tractor driver, Manuel Medeiros, said he did not see any children.
Medeiros declined to respond to questions for this article. He could be fined between $250 and $5,000 per person exposed.
Without clothing samples, the investigation will rely on chemical tests of surface and plant samples collected at the bus stop.
The agricultural commissioner will make the final decision on whether to levy a fine and how much it should be.
Some believe the fines aren't enough.
"The fines are so small that they don't deter the growers," said Teresa DeAnda, an activist with Californians for Pesticide Reform. "The growers just see it as a cost of business."
Growers say they are careful to avoid exposing people.
"We definitely do not like any kind of drift situations where it's affecting human beings, or an animal even," said Nat DiBuduo, president of the Fresno-based Allied Grape Growers, an association that represents about 600 California growers. He said the incident in Caruthers was "rare and unacceptable."
Fresno County has seen a decline in the number of children exposed to pesticides during the last decade, said Deputy Agricultural Commissioner Karen Francone, because of county efforts to teach bus drivers to pull over when they see rigs and to encourage growers to contact transportation authorities before they spray. But even armed with education, some growers still break the law.