LVIV, Ukraine -- Nestled in the historic region of Galicia, this city in western Ukraine is considered one of the country's best-loved architectural and cultural gems.
But in recent months, residents of Lviv have begun to sniff disapprovingly at their historic hometown.
That's because the air has taken on a distinctive stench -- a piquant blend redolent of rotten eggs and untended sewage, with a hint of chemical aftertaste.
The smell has gotten so bad that many residents have begun wearing face masks and keeping children and asthma-sufferers indoors when the odor grows particularly ripe.
Olena, a mother of four, says she's worried about the long-term effect the rotten air may have on her family. "If it was just an unpleasant smell that only lasted for two days, it wouldn't be worth standing here," she says. "But since this is a regular occurrence, we're asking the mayor to deal with it."
Olena was part of a small group of protesters who recently gathered outside the Lviv city hall to protest the stinky air.
Carrying posters reading "We have the right to breathe," the demonstrators gathered signatures from passersby demanding action from the local government.
Government Under Fire
Urban air quality has been an issue for centuries. As early as 1257, the queen of England, Eleanor, was reportedly forced to evacuate her home in Nottingham Castle after being sickened by the smell of sea coal being burned in the city below.
The Ukrainian Constitution, acknowledging the massive environmental impact of the 1986 Chornobyl nuclear disaster, pledges to ensure the country's ecological "safety" and "balance."
But critics say the government has provided little oversight of the country's industrial enterprises -- a problem that Lvivians say has created dangerously malodorous results.
A newly released analysis of the Lviv air has shown high levels of an entire range of pungent colorless gases, including ammonia, hydrogen sulfide, and methanethiol, a substance found in animal feces with a smell like rotten cabbage.
Leonid Zdevoruk, the head of the Eco-West research group that participated in the analysis, says a number of Lviv industries are suspected of being behind the stench.
"We can't say exactly which specific company is causing the odor," Zdevoruk says. "It's a number of reasons together -- the inefficient work of the city sewage plants, the city sewer network, and the lack of local cleaning systems at these companies."
A total of 12 businesses were pinpointed as exceeding waste-dumping quotas, a practice that slows the passage of contaminated sewage to municipal sewage-treatment plants and often exposes the waste to open air, causing a nauseating olfactory brew.
Zdevoruk says some of the businesses to blame for the dumping include the city's First Private Brewery, the Enzym yeast factory, and a local "zhyrokombinat," or butter and lard factory.
What To Do?
However, a study has yet to be conducted at a time when the stench is at its worst. (Many Lvivians say it's the weekends when the air seems especially toxic.)
Many residents have blamed the local authorities for failing to adequately address the problem.
But Mayor Andriy Sadovy, who recently oversaw Lviv's high-profile role as one of Ukraine's four host cities during the Euro 2012 soccer tournament, says it is up to local businesses to build proper treatment plants in accordance with legal guidelines. "If someone doesn't respect the law and the community, we will act accordingly," he said.
The local sewerage operator, Lvivvodokanal, has brought in Polish professionals credited with clearing the air in Warsaw and Brest.
Mykola Odukha, the chief engineer of Lvivvodokanal, says the Poles have already conducted preliminary studies of the city's sewage effluent. "They've conducted the first phase of their analysis," he says. "We're waiting to hear a proposal on how to deal with the problem."
Olena and other protesters say the businesses suspected of causing the stink should be forced to halt operations until they demonstrate they can process their waste in a more sanitary fashion.
Odukha, meanwhile, says he's ready for any bright ideas on how to deal with the problem. "We welcome suggestions about our problems in dealing with untreated sewage," he says.
Written by Daisy Sindelar in Prague, based on reporting in Lviv by Halyna Tereshchuk of RFE/RL's Ukrainian Service