ENVIRONMENTAL campaigners are calling for urgent investigations into air pollution on the Glasgow Subway.

The call comes after a snapshot survey for our sister publication the Sunday Herald found that passengers were breathing in tens of millions of tiny metallic particles that might damage health.

The investigation found levels of pollution by microscopic particles on the Subway up to 10 times higher than on the streets and up to eight times above the World Health Organisa-tion's recommended daily limit.

It has been estimated that passengers on the Subway for 45 minutes could each inhale 60 million particles.

Because the particles are likely to be mostly iron oxide from the grinding of wheels against rails, they may not be as dangerous as particles emitted by trains or diesel cars. But experts and camp-aigners say the risks need examination.

Alison Johnstone MSP, environment spokeswoman for the Scottish Greens, urged Strathclyde Partnership for Transport (SPT) to respond urgently to the findings. She said: "They should ensure that Glaswegians don't find they escape polluted air on the streets only to suffer more severe problems underground."

Air pollution was measured on a 40-minute Subway journey. A portable, state-of-the-art monitor detected concentrations between 40m and 80m particles per cubic metre of air.

In Glasgow Central station levels peaked at just in excess of 40m, and in the city centre they once registered at more than 10m, but were otherwise lower.

Air pollution has been linked to asthma, heart attacks and strokes.

SPT said the survey was alarmist, saying many factors could affect pollution monitors. Its spokes-woman said: "SPT takes passenger and staff health seriously and uses respected industry expertise to guide us on best practice."