Haringey residents suffered from high levels of summer smog and toxic particles during last week's heatwave, according to measures taken in Priory Park.

Figures from a pollution monitoring centre in the park, in Priory Road, Hornsey, revealed that levels of ozone and toxic particles from vehicle fumes, known as PM10s, made breathing more difficult across the borough. With temperatures expected to soar again this week, pollution levels are also likely to rise.

As temperatures crept up, health bosses at the Department for Environment, Food and Rural Affairs issued the first warning of the year on Friday, advising people not to exercise outside, and asking those with respiratory problems to avoid spending time outdoors.

At the peak of pollution on Friday, Haringey's ozone levels were more than double those recorded in May, and PM10 levels were four times higher. A combination of warm, sunny weather and the lack of wind has led to the increased pollution.

Ben Barratt, environmental researcher for the London Air Quality Network, said: "The levels were high and this reflected levels across the whole area. "We have had summer smog ozone is driven by sunlight and we have had a lot of sun, so there is a lot of ozone," he said. "We will find respiratory problems when there is a lot of ozone. The worst day this week was Friday, but levels have dropped slightly. Increasingly, we are finding that some of the particles PM10s have cardiovascular effects, but we are still trying to work out which particles are toxic."