Traffic pollution ‘cause of 33,200 child asthma cases’

A study published today shows that the impact of traffic pollution near busy roads on childhood asthma in European cities is comparable to the impact of passive smoking

Traffic pollution near busy roads has a similar impact on instances of childhood asthma as passive smoking, according to research conducted in 10 European cities and published online today (March 22).

The European Respiratory Journal study shows that an estimated 14% of chronic childhood asthma cases are the result of exposure to traffic pollution near busy roads.

The impact of traffic pollution on instances of childhood asthma is comparable to the impact of passive smoking, research suggests

These findings are comparable, the report authors claim, to World Health Organisation (WHO) estimates that between 4% and 18% of asthma cases in children are linked to passive smoking.

The study, ‘Chronic burden of near-roadway traffic pollution in 10 European cities’, also estimated that a total of 14,400 episodes of asthma symptoms and 260 asthma hospitalisations were attributable to air pollution, accounting for 15% of acute events.

Conducted in Barcelona, Bilbao, Brussels, Granada, Ljubljana, Rome, Sevilla, Stockholm, Valencia and Vienna, the research found that traffic pollution was responsible for an average of 33,200 cases of childhood chronic asthma.

Across the 10 cities considered, the annual weighted mean for particulate matter PM10 was 30 micrograms per cubic metre and 39 mg per cubic metre for nitrogen dioxide. EU annual mean legal limits for PM10 and nitrogen dioxide are both set at 40 micrograms per cubic metre

The study found that on average 31% of the combined population in the 10 cities was estimated to live within 75 metres of a busy road and 53% within 150 metres of such roads.

Previously, traffic pollution was thought to only trigger asthma symptoms and burden estimations did not account for chronic asthma caused by the specific range of pollutants, such as nitrogen dioxide and particulate matter, which are found near heavily used roads.

The study also estimated that an average of 37,200 coronary heart disease (CHD) cases (28% of all older adults with CHD) were attributable to near-roadway traffic-related pollution.

‘improve policy making’

The research used data from existing epidemiological studies which found that children exposed to higher levels of near-road traffic-related pollution also had higher rates of asthma, even when taking into account a range of other relevant factors such as passive smoking or socioeconomic factors.

Scientists used a method known as population-attributable fractions to assess the impact of near-road traffic pollution. This calculates the proportional reduction in disease or death that would occur if exposure to a risk factor were reduced to a lower level. The findings also take into account differences in the health of the overall population in different cities.

Lead author of the study, Dr Laura Perez, of the Swiss Tropical and Public Health Institute, said: “Air pollution has previously been seen to trigger symptoms but this is the first time we have estimated the percentage of cases that might not have occurred if Europeans had not been exposed to road traffic pollution.

“In light of all the existing epidemiological studies showing that road-traffic contributes to the onset of the disease in children, we must consider these results to improve policy making and urban planning.”

Work on the study was undertaken at the Swiss Tropical and Public Health Institute in Basel, Switzerland, and at the Centre for Research in Environmental Epidemiology in Barcelona, Spain. It is available on the European Respiratory Journal website.

UK research published in January 2013 also found that the smoking ban in England coincided with a fall in childhood hospital admissions for asthma symptoms (see airqualitynews.com story).