For almost two weeks, the inhabitants of Crotta d’Adda, a village in the heart of the Po Valley, have barricaded themselves indoors.

Emanating from the vast area of farmland directly adjacent to their homes is an unbearable and potentially noxious stench, which has caused vomiting, breathing difficulties, dizziness, swollen eyes and headaches.

“It is impossible to live like this,” said Cristiano Magnani. “You can’t go out, you can’t do anything. Even your house is no longer safe as the stench gets into everything and lasts for weeks on end. The icing on the cake is that we live in an area surrounded by all the things that cause pollution.”

Crotta d’Adda, home to about 600 people in Cremona, a province south of Milan in Italy’s Lombardy region, is encircled by farms packed with pigs and poultry, from which the faeces are transformed into fertiliser before being thickly coated on to farmland in a process known as “sludge spreading”.

A byproduct of the procedure is “defecation chalk”, a solid material obtained from the hydrolysis of biological materials using lime and, or, sulphuric acid. While defecation chalk is considered to be a versatile product in agriculture, the risk is that the chalks can originate from material classified as waste, and therefore banned from use in fertiliser. However, while the Lombardy region has standards governing sludge spreading, the rules are somewhat vague, making it difficult to control the treatment process and to know if the fertilisers contain contaminants harmful to the environment or human health.

But the sludge is not the only issue blighting the lives of people in Crotta d’Adda and other villages in the Cremona province.

The Po Valley, a huge geographical area straddling northern Italian regions including Piedmont, Lombardy, Veneto and Emilia-Romagna, is among the worst in Europe for air pollution. A Guardian investigation found more than a third of the people living in the valley and surrounding areas breathed air four times the World Health Organization’s guideline limit for the most dangerous airborne particulates.

While the sprawling industrial hubs of Milan and Turin have long been notorious for smog, Cremona, the provincial capital of about 60,000 residents, emerged as one of the cities with the worst quality of air in Europe in a ranking published this year by the European Environment Agency (EEA).

Poor air quality was linked to 50,303 premature deaths in Italy in 2020, according to the EEA, and while most were in Milan, Cremona was the Italian province with the highest proportion of deaths – between 150 and 200 per 100,000 residents – attributed to fine particulate matter, or PM 2.5.

“No body organ is unscathed from PM 2.5,” said Maria Grazia Petronio, a representative from ISDE, an environmental association of medical doctors. “So we are dealing with all types of cancer, respiratory illnesses, fertility issues and also cardiovascular illnesses – when PM 2.5 is high we see an increase in heart attacks.”

Flanked by the Alps and the Apennines, far from the coastline and with little wind, the Po Valley is naturally prone to pollution.

However, as Italy’s economic powerhouse, the area is also heavily industrialised and agriculture-intensive. Lombardy produces huge amounts of animal waste, much of it concentrated in farms in Cremona and neighbouring provinces, while the region produces more than 40% of Italy’s milk and hosts the largest number of pigs.

Cremona’s pollution woes are also due to a steel factory close to Crotta d’Adda, an ageing waste incinerator and the constant passing of heavy vehicles.

“We really don’t miss a thing around here,” said Giovanna Pirotta, a volunteer in Cremona with Legambiente, Italy’s most prominent environment association.

But while the issue of bad air in Cremona, an otherwise refined city famous for violin-making, has long been known, Pirotta said the topic, especially when it came to premature deaths, was mostly “swept under the carpet”.

“Unless they’ve really been affected by it, people here like to pretend as if nothing is happening. In reality, the atmospheric conditions are worsening, also because of the changing climatic conditions.”

While local initiatives such as cycling paths and restrictions on pollution-emitting vehicles have gone some way to tackling smog across the Po Valley, authorities hesitate to take stronger action as it would come at an economic cost.

“If we know that the main source of pollutants are cars, then why is there not a strong intervention on sustainable mobility?” said Michele Arisi, from Stati generali Clima Ambiente e Salute, a Cremona-based environment association. “While you see a lot of bikes in Cremona, it is also the city with one of the highest ratios of cars per citizen.”

Arisi’s association has come together with others, including Critical Mass, launched last year by a group of young people to raise awareness about environmental issues, to fight plans to build a new shopping centre and motorway.

“[The authorities] are aware of the pollution problem but act in the opposite way by creating even greater hubs for traffic,” said Arisi.

As part of a plan drawn up alongside authorities in Piedmont, Veneto and Emilia-Romagna, the Lombardy councillor for the environment, Giorgio Maione, argues that the region has made good progress in recent years in its attempts to reduce pollution.

Over the past decade, the level of coarse dust particles (PM10) in Lombardy, a region with more than 10 million inhabitants, has been gradually decreasing, as has the number of days in which the 50mg/m3 limit was breached, even if the 35-day limit was still exceeded in 2022.

Measures including traffic restrictions, greener heating systems and providing financial incentives to encourage people to improve home insulation, as well as those targeting the agricultural sector, have contributed to the improvement.

Maione said Lombardy invested €19bn (£16bn) on such initiatives between 2018 and 2022, the bulk being spent on improving mobility infrastructure, including incentives allowing residents and businesses to swap vehicles for cleaner ones.

He argued that the region was making “an enormous effort” but that it was impossible to meet the EU’s 2030 air quality targets due to the disadvantage of its geographical location. Italy is among countries pushing for the rules to be loosened.

“We’re not against the objectives, we are asking for a different approach, such as extending the timeframe,” said Maione. “Even the EU says that the goal is not technologically achievable today, even with the best existing technologies, without stopping use of all cars, closing businesses and all of our production activities and eliminating livestock.”