People are burning smoky coal in Northern Ireland to save money on fuel - at the cost of widespread air pollution.
Heating is more expensive in Northern Ireland than in Great Britain and poverty levels are higher.
The findings of a report investigating the impact of polycyclic aromatic hydrocarbons on air quality have been presented to Northern Ireland district councils.
They are carcinogenic pollutants and research suggests there are higher levels in many urban areas across Northern Ireland than is allowed under EU targets. This is mostly caused by households burning smoky coal.
The report said exposure to current levels in urban centres in Northern Ireland could lead to 12 cases of lung cancer in Northern Ireland over a 70-year lifetime.
Smoke control is the main way of tackling pollution levels. District councils designate smoke control areas and enforce control measures.
Environment minister Alex Attwood said: "The burning of smoky coal in towns and cities across Northern Ireland, particularly in cold weather, is leading to relatively high levels of these pollutants in the air we breathe.
"I would encourage people to burn only smokeless coal. It is slightly more expensive but scientific evidence shows that smokeless coal burns longer with a higher heat output which would negate the perceived savings on smoky coal."
Unrelated research from the Consumer Council said: "72% of households in fuel poverty use oil or natural gas as their main heating fuel. These are the most energy efficient ways to heat your home yet so many in Northern Ireland remain in fuel poverty.
"This shows how energy efficiency measures alone will not tackle fuel poverty."