ASTHMATICS and people with heart conditions have been warned about high levels of pollution.

The warning comes after air quality monitoring stations across the borough of Stockton detected higher than normal pollution levels, particularly small dust particles, known as PM10s.

People who are at risk and live on or near Yarm's busy High Street are being told to be particularly careful.

Environmental experts say the warm weather the area is enjoying is mainly to blame for the increase in airborne pollutants.

The warm, windless weather is expected to continue until the weekend.

Asthmatics are advised to avoid excessive exercise, particularly near busy roads, although inhalers are believed to help relieve the pollutants' effects.

Steve Smith, principal environmental health officer for Stockton Borough Council, said healthy people had little to fear from the conditions.

He said: "We're keeping a close eye on pollution levels throughout the borough. Low winds and high atmospheric pressure are combining to trap pollution close to the ground level and allowing it to build up.

"These levels do not pose a danger to the majority of people. However, sensitive people, such as those who suffer from lung and heart disease, and asthma, should reduce their exposure to pollution if they can."

As temperatures reached the low 20s yesterday, Mr Smith said the light easterly winds predicted for the rest of the week could increase the pollutant levels in the Tees Valley.

It is thought that air-blown particles from the continent combine with pollution from Teesside and are trapped in the low-lying river valley to create uncomfortable conditions for asthmatics, joggers and the elderly.

Mr Smith said: "In the 1960s we had the image of the Teesside smogs, but those days are long gone as industries have cleaned up their acts.

"The main enemy is the car and pollutants close to ground level. People should really consider using their cars less during times like this."

Details about pollution levels are available at www.air quality.gov.uk, www.stockton. gov.uk, on Ceefax page 155, or on freephone 0800 556677.