Noxious

Exhaust gases of a car are noxious.

Behind the house there was an old orchard, now overrun with noxious weeds and rough shrubs.

Noxious fumes may be present.

The smell was noxious.

The old warehouse is no longer storing any noxious chemicals.

Noxious fumes are likely present.

In the living state, the body is observed to […] reject what is noxious; [...]

[...] many old sewers have been neglected and are in dire need of repair. If that repair does not come in time, the result is noxious and potentially hazardous.