Air pollution, lack of access to green space can increase likelihood of ADHD as much as 62 per cent: B.C. research

A peer-reviewed study conducted in Metro Vancouver suggests a link between air pollution and attention-deficit/hyperactivity disorder.

Researchers from the University of British Columbia said their study found children who grow up in neighbourhoods with more green space and less air pollution were less likely to develop ADHD.

Characterized by symptoms including difficulty with impulse control and paying attention, ADHD is one of the most common neurodevelopmental disorders in children and teens. It is estimated to impact about five to 10 per cent of youth around the world.

The study published on ScienceDirect was the first to look at green space, air pollution and noise in combination, UBC said in a news release. Population-based studies have been conducted, the researchers said, but they've been limited, and "joint effects are rarely evaluated."

This study involved administrative data from births in 2000 to 2001 in the Vancouver area – about 37,000 children – and ADHD diagnoses identified in hospital records, doctor visits and prescriptions.

Researchers used land-use regression models and vegetation percentage, and looked at an exposure period for each child of birth to the age of three.

Seven years later, 1,217 of the children had been diagnosed with ADHD.

What researchers said they found was that noise had no association with ADHD, but the first two factors can have a significant impact.

"We found evidence suggesting environmental inequalities where children living in greener neighbourhoods with low air pollution had substantially lower risk of ADHD compared to those with higher air pollution and lower green space exposure," they wrote in the piece published by ScienceDirect, a website that hosts content from academic journals.

They said the risk of ADHD can be as much as 62 per cent higher for children in areas with lots of air pollution and not much green space.

But they also found that one factor can compensate for the other, so a child living in an area with high air pollution but access to plenty of green space has a lower risk, and vice versa.

Those behind the research hope their work will be used by urban planners and municipal governments as they look to maintain the mental health of residents over time.

Additionally, the information could be used by parents, who may make a point of encouraging more outdoor time, and by school staff.