Fine air pollutants may contribute to the development of asthma and wheezing in children, according to a study by researchers in Denmark.

They found children exposed to higher levels of fine particles in the air – known as PM2.5 – were more likely to develop asthma and persistent wheezing than children who are not exposed.

Other risk factors were having parents with asthma, having a mother who smoked during pregnancy, or having parents with low education and low income.

The findings, published in the British Medical Journal, support emerging evidence that exposure to air pollution might influence the development of asthma, said the researchers.

They noted that PM2.5 could come from various sources, including power plants, motor vehicles and domestic heating.

The study authors highlighted that the particles – about 3% or less of the diameter of a human hair – could penetrate deep into the lungs and some may even enter the circulatory system.

Short term peak exposure to pollution has been associated with worsening of asthma, by they said the risks of long-term exposure and the timing of exposure for the onset of asthma was less clear.

In addition, the role of air pollution combined with other risk factors, such as socioeconomic status, on asthma was unclear, noted the researchers.

They assessed data on more than three million Danish children born from 1997 to 2014, of which 122,842 children were later identified as having asthma and persistent wheezing.

This information was then linked to detailed air pollutant measurements at the children’s home addresses, parental asthma, maternal smoking, parental education and income.

The researchers said they found higher levels of asthma and persistent wheezing in children of parents with asthma and in children of mothers who smoked during pregnancy.

In contrast, they noted that lower levels of asthma and persistent wheezing were found in children of parents with high educational attainment and high incomes.

According to the researchers, their findings “support emerging evidence that exposure to air pollution might influence the development of asthma”.

They stated: “The findings of this study suggest that children exposed to higher levels of PM2.5 are more likely to develop asthma and persistent wheezing than children who are not exposed.

“Other risk factors associated with these outcomes were parental asthma, parental education, and maternal smoking during pregnancy,” they added.

Air pollution ‘linked’ to higher risk of children developing asthma | Nursing Times