Children who are exposed to higher levels of PM 2.5 (fine particles in air) are at a higher risk pf developing asthma or persistent wheezing compared to kids who are not exposed.
The study which was published in The BMJ journal adds to the rising evidence which suggests that exposure to pollutants in the air can influence development of asthma in children. Other risk factors linked with heightened asthma risk and persistent wheezing are parental history of asthma, smoking during pregnancy, and parents with low income and education. The fine particles or PM 2.5 emerge from different sources such as motor vehicles, power plants, heating system in the house and others. Particles which are around 3% or lesser that the width of human hair are able to infiltrate the lungs deeply and some even penetrate the circulatory system. Peak exposure for a short term to this particles can result in worsening of existing respiratory condition, although, risk of long term contact and the timing of contact for asthma onset are not as clear. Moreover, effect of air pollution in combination with the aforementioned risk factors on asthma risk is also not clear.
A research team in Denmark analysed data of nearly 3 million children born between 1997 and 2014 related to asthma onset and persistent wheezing between the ages of 1 to 15 years. 122,842 children developed asthma and persistent wheezing around the age of 1 and 2. The information was traced back to the home environment of the children, parental asthma, education of parents, maternal smoking, and income of the parents. High levels of asthma and wheezing was linked with parental asthma and maternal smoking. Lower levels were identified in children whose parents were highly educated and had higher incomes. Exposures to PM 2.5 and PM 10 as well as nitrate were linked with higher risk of asthma and persistent wheezing.