Appeal judges are considering a legal fight centred on a landfill site which locals say gives off noxious gases and stinks.
A woman who lives near Walleys Quarry in Silverdale, Staffordshire, took legal action against the Environment Agency on behalf of her five-year-old son and won a fight in the High Court in September.
Environment Agency bosses have mounted a challenge in the Court of Appeal.
Three appeal judges are considering the case at a hearing in London due to end on Wednesday.
Rebecca Currie, whose son Mathew Richards was born prematurely with a chronic lung disease, had told a High Court judge that fumes from the site gave off “a stomach-wrenching smell like rotten eggs”.
Lawyers representing Ms Currie and Mathew argued, at the High Court hearing, that there was a “public health emergency” in the vicinity of the site and said hydrogen sulphide emissions were affecting “hundreds and probably thousands of local people”.
Mr Justice Fordham made a declaration that the EA “must implement” Public Health England’s advice to reduce concentrations of hydrogen sulphide in the local area to one part per billion, less than an eighth of the level that can be smelled, by January 2022.
Lawyers representing the Environment Agency say the declaration was unjustified.
Ms Currie says the agency’s appeal should be dismissed.
