Dallas, TX – Dallas ISD is checking the air quality at Lakewood Elementary because of parents’ concerns about a possible carbon monoxide leak.

The district has not yet released any findings on the school’s air quality, but the school is open this morning, district spokesman André Riley said.

Staff monitoring began this weekend and was expected to end at 7 a.m., when a third party took over, said district spokesman André Riley.

Some children have been reporting headaches and nausea. In March, a gas leak sickened more than a dozen children and several teachers, prompting parents to demand improvements at the aging school.

“In addition to the installation of a professional-grade carbon monoxide monitor during the previous year, the district will dispatch personnel today as well as deploying data loggers to monitor conditions at the school,” the district said in a written statement Sunday.

Voters approved a $1.6 billion bond package last year that included $3 million for renovations at Lakewood.