As soon as Christina Whitaker stepped inside D.C. General, the District’s troubled and dilapidated mega-shelter for homeless families, she knew she had to get out.

“Filthy” living conditions and dust immediately caused her 3-year-old grandson’s asthma to flare. Amir began wheezing at night — once so badly that an ambulance was called — and woke up most mornings to find his eyes swollen shut with rheum.

And Whitaker knew things were about to get worse — the city will begin demolishing a vacant building just 250 feet from D.C. General’s main shelter next month, possibly exposing residents to lead and asbestos. Advocates and health experts are demanding the city relocate the more than 150 families living in D.C. General before demolition begins.

On Tuesday, staffers for D.C. Council member Trayon White Sr. (D-Ward 8) said he intends to introduce emergency legislation that would bar the city from beginning demolition until all current residents have found new homes, according to Amber Harding, an attorney with the Washington Legal Clinic for the Homeless.

“The city is proposing to start demolishing a large building feet away from where those children and those families play in the playground, where they eat their meals,” Harding said. “Our position is it’s the city’s responsibility and the council’s responsibility to protect those children and their parents from the environmental and health hazards that the city is going to cause.”

Brian Butler, project manager with the Department of General Services, which is overseeing the demolition, said the city is taking every precaution to ensure the safety of residents at D.C. General.

He confirmed the building slated to be demolished contains lead and asbestos but said officials are going “above and beyond” by conducting extra testing not mandated under federal demolition regulations.

“Safety is the number one priority — we’re taking this building down in a very slow, systematic way to ensure that the process is done correctly and safely,” Butler said. “If I felt it wasn’t being done safely, I would be the first person to put my hand up and say, ‘Stop.’ ”

D.C. Council member Mary M. Cheh (D-Ward 3) said late Monday that White’s D.C. General legislation has gone through multiple revisions and that it was unclear exactly what the bill would contain if and when it came up for a vote Tuesday.

White did not respond to repeated requests for comment.

The Whitakers have left D.C. General, but hundreds of others remain. A Department of Human Services spokeswoman said 155 families — including 289 children — live at the shelter.

No matter the extra precautions, several doctors and demolition experts said they believe these families will suffer health complications if they are not gone before August.

Lead poisoning poses a particular risk for young children, said Janet Phoenix, an assistant professor at George Washington University and an official with Breathe DC, which tracks asthma in the city. Demolition can release lead-containing dust particulates — and children, who “have a lot of hand-to-mouth” activity, may end up swallowing lead, which can cause brain damage. There are no safe levels of lead exposure.

“Whether it’s the ability to acquire language skills or whether it’s growth and development, hearing, intelligence, all of those things are adversely affected by lead,” Phoenix said. “And the results are irreversible — so the damage that gets done as a result of the exposure can’t be turned around.”

Phoenix said she would “strongly” recommend that D.C. General be emptied before demolition begins. Eileen Moore, who oversees a Georgetown University health clinic inside the shelter staffed by volunteer student and attending physicians, said residents are already struggling.

Two to three D.C. General residents come to the clinic with breathing trouble on any given night, Moore said.

Children and adults with lead poisoning are at an elevated risk for asthma. Elizabeth Gates, a pediatrician who has treated scores of children living in D.C. General, previously estimated one-third are asthmatic.

Harding said almost no one disagrees that D.C. General should be torn down — the shelter, which first attained notoriety after 8-year-old resident Relisha Rudd disappeared in 2014, is widely known as unsanitary and unsafe.

If White’s legislation falters and the city moves forward with the August demolition, the Washington Legal Clinic will consider suing on behalf of shelter residents, she said.

The fall closure of D.C. General is at the center of Mayor Muriel E. Bowser’s signature plan to replace the mega-shelter with a network of smaller facilities spread across the city.

But her replacement plan has encountered delays, with construction of two of those smaller shelters behind schedule.

Bowser (D) announced in January that her administration would shut down the shelter on the grounds of the former D.C. General Hospital by the end of the year, even though not all of the replacement facilities would be ready.

She said families that would have been sent to D.C. General would instead be housed at the new shelters in Wards 4, 7 and 8 scheduled to open in the fall, with motels handling overflow.

But the contractor building the new shelters ran into problems, particularly with one subcontractor who had no experience constructing the type of buildings planned for the shelters. The city and contractor pushed back the deadline for “substantial completion” of the new shelters from Aug. 31 to Oct. 1.

Greer Gillis, director of the D.C. Department of General Services, which oversees city-owned property, told The Washington Post two weeks ago that shelters in Wards 4 and 7 should be ready by October but that it is uncertain whether the Ward 8 shelter will open by then.

The remaining shelters in Wards 3, 5 and 6 are scheduled to start operating next summer, while a shelter in Ward 1 is set for summer 2020.

Despite the delays, city officials have not wavered in their plan to proceed with the demolition next month.

Correction: An earlier version of this story incorrectly reported that children and adults with asthma are at an elevated risk for lead poisoning. The inverse is true. This story has been updated.