The haze has cast a shadow on the Singapore leg of the Fina Swimming World Cup, which is scheduled for today and tomorrow.

Organisers revealed yesterday that if the three-hour Pollutant Standards Index (PSI) exceeds 200 at the start of each session, the latter will be cancelled.

There are four sessions at the OCBC Aquatic Centre - two morning heats and two evening finals. The heats start at 10am, one hour later than usual, while the finals commence at 6pm.

If the heats are cancelled, the swimmers with the top 10 seed times will swim in the final.

If the finals are cancelled, the three fastest swimmers in the heats will be awarded the medals.

In the event of cancellation, ticket-holders of the affected sessions will be refunded.

The women's 800m and men's 1,500m freestyle events have been scrapped. The top three will be determined by the best times from the two most recent races in Hong Kong and Beijing.

In addition, events with 25 or fewer competitors will be held in a timed finals format - each swimmer will swim just once and the top three finishers will win a medal.

Fina executive director Cornel Marculescu said yesterday: "We are deeply disappointed with the haze threat. However, the health and safety of our athletes, guests, officials, volunteers, spectators and staff are our top priority."

A health advisory on the National Environment Agency website recommends that healthy people "avoid prolonged or strenuous outdoor physical exertion" when the 24-hour PSI is in the 201-300 range.

Chua Siang Yee