Wood-burning smoke at home may expose children to pollution rivalling traffic exhaust, six-city study finds

Smoke from burning wood to heat homes could expose children to pollution as significant as traffic exhaust, according to new research across six European towns and cities.

Scientists measured the air in buildings where children spend much of their time — schools, sports centres and homes. They looked specifically at polycyclic aromatic hydrocarbons (PAH), a family of pollutants given off when fuels are burned.

Measurements were made in and around Athens, Barcelona, Colchester, Copenhagen, Helsinki and Lisbon.

Dr Barend van Drooge, of Barcelona's Institute for Environmental Assessment and Water Research (IEAWR) and senior author of the study, said some of these compounds are related to cancers after prolonged exposure, as recognised by the International Agency for Research on Cancer, and evidence exists that they delay cognitive development.

Van Drooge said urban areas with wood-burning, such as Colchester and Athens, had the highest PAH levels, while Barcelona and Lisbon, where wood-burning is not practised, had the lowest.

In Colchester and Athens, PAH exposure was greater than World Health Organization guidelines.

Maria Antonia Aretaki, of the IEAWR and first author of the study, said understanding the pollutants in children's everyday surroundings is an important step towards protecting their health, given children's vulnerability to environmental pollutants and the potential health implications of exposure during childhood.

Concentrations also varied by place. Sports centres had the lowest concentrations, followed by schools, though some schools in Lisbon were affected by nearby busy roads. Ventilation and indoor sources mattered, but many of the homes with the greatest PAH were in wood-burning areas and had open fireplaces and stoves.

The seasonal effect was clear: winter PAH concentrations were greater than in summer. In Colchester homes, high-molecular-weight PAH in winter were more than 10 times the summer levels, while low-molecular-weight PAH were around three times greater.

Van Drooge noted, however, that none of the cities exceeded unacceptable limits for lifetime cancer risk. He said wood-burning is known to be an important emitter of PAH, but it was surprising that it has become such an important contributor to their overall presence in urban areas.

Within the UK, separate analysis of energy performance certificates by researchers at University College London showed Colchester ranked 120th out of 333 local councils for density of wood burners per square kilometre, while Worthing, Norwich and Reading all had around four times more.

A wintertime study of 53 children from two primary schools in Anglesey found that children living in homes with wood burners could be exposed to over three times more particle pollution than those in non-wood-burning homes, and that homes had more air pollution than schools.

The research also recalled Greece's experience. Wood-burning increased there during the financial crisis that began in 2008, when the cost of heating oil soared and many people turned to wood heating. This contributed to increased deaths associated with particle pollution in Athens, especially among those aged over 70, and in some Greek towns wood-burning leads to PAH levels 100 times greater in winter than in summer.