A HEALTH warning was issued last night after danger levels of chemicals were recorded in the North-East's air.

Ozone and dust levels breached national safety limits over Teesside.

Asthmatics are being advised to stay at home until the alert is over, joggers to hang up their running shoes; while motorists are being urged to leave their car at home if possible.

With more sunshine and high temperatures forecast for the weekend, families are being asked to shelve plans for barbecues and DIY enthusiasts to postpone plans to creosote the fence.

The fumes from both activities will further feed the high pollution levels.

Jeff Duffield, group leader in public protection with Middlesbrough Borough Council, said: "It is a health warning.

"Health standards in two areas have been breached and if this weather continues they will be breached again.

"People who are susceptible to respiratory problems - asthmatics, old people and young people - need to limit their exposure to the outside air.

"We are also advising people to avoid strenuous exercise - keep exercise to a minimum, because breathing harder means breathing more in.

"Our second message is: if you don't have to use your car, then please don't, and don't have any bonfires."

The problem is caused by a combination of weather and geography.

Toxic particles which had been blown over the sea from Europe found themselves trapped in the low-lying Tees river basin as the wind dropped.

As the land heated up in yesterday's sunshine, the air rose, causing a partial vacuum which sucked in even more chemical dust from across the sea.

The safety limit for PM10s - microscopic dust particles that attack the lungs - is 50 microgrammes. On Teesside yesterday, levels were recorded of 88 and 94 microgrammes.

The national safety limit for ozone is 50 parts per billion, but levels have risen to 64, 74 and 81 parts.

Mr Duffield described what was happening as a photo-chemical smog - invisible to those living and working underneath it.

He said: "If the wind is from the south-east this problem is going to get worse.