Why you shouldn't pedal too quickly

Lycra louts who whizz through the city streets may be doing themselves more harm than good, scientists claim.

Cycling or walking too fast actually causes people to breathe deeper - drawing more toxic air pollution into their lungs. But they also found the quicker people pedal, the less they are actually exposed to road smog.

Experts now believe they have worked out the optimal speeds for walking and cycling to minimise their inhalation.

Cyclists should ride between 7.5mph (12kph) and 12mph (20kph) on city roads while pedestrians should keep between 1.2mph (2kph) and 3.7mph (6kph).

But average speeds depend on age and older people should aim to go a little bit faster, researchers advise.

Lead researcher Dr Alex Bigazzi, from the University of British Columbia, said: 'The faster you move, the harder you breathe and the more pollution you could potentially inhale, but you also are exposed to traffic for a shorter period of time.

'This analysis shows where the sweet spot is.'

Researchers calculated ideal travel speeds using data from more than 10,000 people.

The estimates, referred to as minimum-dose speeds (MDS), are average speeds and based on flat roads of pavements.

They found young female cyclists should stick to 7.8mph (13kph) while males under 20 should keep to 8.3mph (13kph).

But older cyclists of both sexes should attempt to stick at 9.3mph (15kph) to minimise their inhalation of air pollution.

For young pedestrians under 20 the ideal walking pace is 1.9mph (3kph) while older people they should strive to reach 2.5mph (4kph).

Professor Bigazzi added: 'If you move at much faster speeds your inhalation of air pollution is significantly higher.

'The good news is, the MDS numbers align pretty closely with how fast most people actually travel.'

Air pollution has been found to increase the risk of developing asthma, strokes and lung cancer. It is believed to be responsible for three million deaths worldwide.

The study comes after research found last month that more than 90 per cent of the UK's population is living in areas where air pollution exceeds safe limits.

The new study was published in the International Journal of Sustainable Transportation.

Source: Daily Mail

(Dhaka times/07 July)