Tired of endless traffic? Cycle or walk instead - because the benefits of outdoor exercise can‚ even if you live in Johannesburg‚ outweigh the damage caused by air pollution. A study published in the journal Preventive Medicine has used data to calculate how long a person can exercise before the risks of air pollution such as fine particulate matter‚ with a diameter of less than 2.5 micrometers‚ take a toll on the human body – depending on the levels of pollution in various cities. And the good news is that Johannesburg‚ despite its reputation for heavy traffic and pollution‚ fares far better than many other cities across the globe.According to the World Health Organisation’s (WHO) latest dataset on air pollution‚ Johannesburg has an annual average fine articulate matter (with a diameter of less than 2.5 micrometers ) concentrations of 41 micrograms per cubic meter (μg/m3).Marko Tainio‚ a health impact assessment modeller at the University of Cambridge in the UK‚ said that in that concentration‚ the average Johannesburg cycler “could cycle seven and a half hours per day‚ every day of the year‚ until the harm of the air pollution would become larger than the benefit of physical activity.”While Indian cities largely dominate the higher ranks of the WHO database‚ the Iranian city of Zabol‚ was ranked at the top with a PM2.5 rate of 217μg/m3.“In this city‚ after 30 minutes of cycling per day‚ the risks become as big as the benefits. For walking it is two and half hours per day‚” Tainio says.“In global air levels‚ pollution levels in South Africa are higher than the levels in Europe and North-America‚ but are lower than the levels in South-East Asia‚” he added.The most polluted town recorded in South Africa was Hartebeespoort‚ also known as “Harties” in the North West Province‚ with 60 μg/m3.But Tainio said that he would not propose any guidelines in any city in South Africa for restricting walking or cycling (or any other physical activity).“Quite contrary! I would propose walking and cycling more because it is good for health! If possible‚ it would help to exercise further away from the roads and other high air pollution environments‚” he said.“For walking‚ results are a bit different.“Air pollution would never overcome the benefits of walking‚ even if person would walk 16 hours per day‚ every day of the year‚” he said...