The smoke from cannabis could be dangerous to others. THOMAS Samson/AFP via Getty ImagesChildren whose parents smoke, vape, or use cannabis seem to have slightly more respiratory infections than children whose parents don't smoke, or who just smoke.According to Adam Johnson, a Wake Forest School of Medicine North Carolina physician, the effect could be caused by children inhaling second-hand marijuana smoke. Because irritants are being ingested by children's lungs, it would make any [respiratory] viral more severe.Second-hand tobacco smoke is known to cause more respiratory diseases in children who inhale it. This has led to some countries banning people from driving with children. The effects of cannabis smoke are not well understood, particularly since people smoke less marijuana cigarettes per day.AdvertisementThis new study was conducted in Colorado, which legalized recreational cannabis in 2014. Johnson's team interviewed 1500 parents of children who were admitted to a hospital paediatric emergency room for any reason. Half of caregivers used marijuana only, and 10% smoked or vaporized marijuana.The parents were asked to tell their children about any illnesses they had suffered in the last year. The average number of viral respiratory infections suffered by children whose parents used marijuana or vaped it was 1.3. Those who did not smoke and those who smoked only tobacco were at a lower risk of getting about 1.The team found that there was no significant difference between the types of asthma exacerbations. This may be because these incidents occurred at low rates of about 0.2 per child over the course of the year.Johnson says that the study does not prove that cannabis smoke causes the infections. However, the idea is plausible. It could be that the parents' memories of illnesses, rather than medical records, are limiting.The fact that second-hand tobacco smoke can cause ill health can complicate research. This study found that smoking or vaping marijuana was associated with higher education levels and income than the average.Journal reference: Pediatric Research, DOI: 10.1038/s41390-021-01641-0
