Testing has begun on 20 homes near a car plant following the discovery of contaminants in groundwater and soil in the surrounding area.
Original testing detected evidence of solvents in the soil and groundwater near the Holden factory at Elizabeth last year.
Letters were then sent to 95 nearby Housing SA homes at Elizabeth South, which were identified in a wider contamination zone.
Of these, 20 are now having air tests taken beneath their floorboards to see if the chemicals have entered the home.
The air samples collected below the homes will be tested in Victoria with an independent auditor to review the results.