As winter arrives, Bulgarians are worried about the impact of rising air pollution levels on top of the spread of COVID-19.
Brussels has sanctioned the government, accusing it of doing nothing about the pollution.
While lockdown has improved air quality in Europe, Sofia, one of the most polluted cities in the world, regained its thick "smog" as restrictions were lifted.
"Seen from above, the city looks like a greyish lake of dirt, we reluctantly returned" to the capital after our weekend getaways, said Gueorgui Pavlov, a 39-year-old computer scientist.
"Even before the COVID-19, I got myself a reinforced filter mask, just to walk the dog in winter," the Sofia resident said.
Ina Hristova, a 28-year-old biology researcher, makes sure she covers her face, to protect herself "not only from the COVID-19, but also from all the dirt in the air".
She has placed gauze across her child's pushchair when she goes on walks 4 km away from her home, in her quest for "more breathable" air.
Coal, wood and tyres
In recent days, criticism of governance and the quality of life in Bulgaria have flooded social media.
On several occasions recently, the concentration of fine particles PM 10 (inhalable particles, with diameters that are usually 10 micrometres or smaller) in 24 hours has far exceeded the standard set by the World Health Organization (WHO), according to reports.
Last week, the European Commission also called Bulgaria to order and is going to take legal action for "systematic" non-compliance with these limit values. The government "has not really started to implement measures on the ground", said Brussels.
The culprits for the smog are dust from heating with coal or wood, but also from tires, old furniture or plastic burnt in poor neighbourhoods and the exhaust fumes of an ageing car fleet.
Sofia is not the only city affected by the pollution issue in Bulgaria. "In my hometown in the north, in the middle of the mountains, all the chimneys smoke and spread an unbearable smell that takes your breath away. It's a problem that is present on a national scale," said Hristova.
The coronavirus pandemic has exacerbated concerns surrounding the pollution for many.
The World Health Organisation has said: "Air pollution increases the risk of respiratory and heart disease in the population. Both short and long term exposure to air pollutants have been associated to health impacts."
"There is not a single organ in the body that is not affected by fine particle pollution" and it acts "in synergy" with COVID-19, pulmonologist Alexandar Simidtchiev told AFP.
The number of deaths linked to the pandemic reached an unprecedented level last week in Bulgaria, with 983 deaths between December 1 and December 7, for nearly seven million inhabitants.
Initially reluctant to restrictions, the contested conservative government of Boyko Borissov has decided to close restaurants, schools and shopping centres to relieve overwhelmed hospitals.
The COVID-19 crisis has highlighted issues in Bulgaria that have caused an "explosive cocktail" for the poorest country in the EU, Simidtchiev said.
Chronic pollution, a lack of pulmonologists, a large number of smokers and an increasingly elderly population are among the matters he underlined as contributing to the situation.