Pima County warns residents near I-10 hazmat incident about possible breathing troubles

Pima County issued a public health advisory for residents living within a one-mile radius of Tuesday's chemical spill on Interstate 10, advising them to seek medical attention if any breathing problems arise.  

A truck carrying nitric acid, a major component in fertilizer, caused the incident when it toppled on a stretch of I-10 between Kolb and Rita Road on Tuesday afternoon. East Side residents living as far south as Valencia Road and as far east as Houghton Road were advised via an emergency text alert to shelter in place and keep their heating and cooling off to prevent inhaling the toxic fumes. It also caused the Vail Unified School District to cancel classes on Wednesday.

En español: Condado Pima advierte a residentes cerca de incidente de fuga de químicos en I-10 sobre problemas respiratorios

The advisory was issued Wednesday, following a limited evacuation of the area around the crash site on Tucson's Southeast Side right after the crash.

The spilled nitric acid released a reddish-orange plume as well as hazardous nitrogen dioxide, a gas that’s also a common but harmful air pollutant. A fire was also sparked by the crashed truck in the median of the highway.

Nitrogen dioxide, or NO2, can damage tissue and irritate lungs and airways badly enough to require immediate medical attention and hospital admission. It's considered “slightly irritant gas,” according to a Pima County health advisory, but concentrated exposure to it, especially while in a confined space, can cause delayed lung and breathing problems up to 24 hours later.

Anybody who believes they’ve been exposed to released nitrogen dioxide for at least 15 minutes should be cautious about possible breathing problems arising, the Pima County Health Department and Arizona Poison and Drug Information Center warned in the advisory.

People within a one-mile radius of the accident who had enough exposure to the gas might develop symptoms such as wheezing, shortness of breath, labored breathing or worsened asthma and COPD.

If anyone is feeling those symptoms or similar breathing problems, they should seek a medical evaluation from a doctor, urgent care center or emergency room, the county warns. If exposed, people will likely have delayed symptoms 12-24 hours later.

People living within one mile of the incident may have been exposed to the chemical fumes if they were inside their house but using climate controls that pulled air from outside, the county warns. Many heating and cooling systems include "make up air" that mixes outside air with recirculating air.

Drivers who passed the crash site and chemical plume, however, should be fine as they likely avoided the 15-minute threshold, according to the health advisory.

Pima County has a chart online to help people decide if they need to call 911 or go to urgent care or the ER.

Updates on the accident and details about where it took place are being posted online by the Arizona Department of Public Safety, which patrols the state’s highways.