Toddlers who live in areas with moderate air pollution may have a higher risk of middle ear infection.
The findings, reported in the journal Epidemiology, do not prove that air pollution itself was the cause. But if it is, that would allow parents to influence their kids' risk of infection by moving to a place with better air.Middle ear infections
, also called otitis media, are common among young children, with those younger than 2 being most susceptible. They are caused by a viral or bacterial infection, and usually arise after a child has had a cold, sore throat or other upper-respiratory tract illness.
Earlier studies have suggested that air quality can play a role in young children's vulnerability to middle ear infections; exposure to second-hand smoke
, for instance, has been linked to an increased risk. But little research has looked at the relationship between outdoor air quality and ear aches.
For the new study, researchers tracked doctor visits for middle ear infections among more than 45,000 children followed from birth until age 2. All of the children lived in an area with relatively good air quality.
The investigators used data from government air-quality monitors to estimate each child's exposure to air pollutants, based on the family's home address. They then looked at the relationship between the children's ear infections and their air-pollution exposure in the two months prior to the infection.
Overall, 42% of the children visited the doctor for a middle ear infection at least once in the first two years of life. When the researchers looked at air pollution levels, they found a correlation between ear infections and exposure to certain pollutants even with factors such as the time of year (ear infections are most common in fall and winter), neighbourhood income levels and whether mothers smoked during pregnancy
For example, when dividing children into four groups of exposure to nitric oxide, a traffic-related pollutant, those with the highest exposure were 10% more likely to have a doctor visit for middle ear infection than those in the lowest.
Two other pollutants were also linked to moderately increased risks: particulate matter, the fine particles emitted via car exhaust, as well as power plants and other industrial sources and smoke from wood burning.
Children breathing the highest levels of wood smoke were 32% more likely to have doctor visits for middle ear infections than those breathing the least.
No other individual pollutants were tied to children's risk of infection.
In general, experts recommend that parents help lower their children's risk of the infection through regular hand-washing to cut the odds of catching a cold or the flu, keeping children upright during bottle-feeding and having them receive the recommended vaccines against the flu and pneumococcal infection, either of which can lead to a middle ear infection.Does your child suffer from middle ear infections?