Key points from article :
People living by loud, busy roads have larger hearts on average.
Even though exposure was to pollution levels below UK guidelines.
Exposure to higher pollution levels linked to larger ventricles .
One microgram of PM2.5 caused the heart to enlarge by about 1%.
Every 10 extra micrograms per m3 of NO2 had the same effect.
Queen Mary University studied 4,000 people in the UK.
The study was published in the journal Circulation.