London is a city with notoriously high nitrogen dioxide (NO2) levels and prior to the start of the 2012 Olympic Games, concern was voiced over the performance of athletes competing in the Games.

The levels of NO2 in London’s air are comparable to Beijing which hosted the Olympics in 2008. High levels of pollutants in the air can cause lung, throat, nose and eye irritations which were seen as a threat to the success of the athletes. A study by the University of Western Australia found that around 8% of Olympians suffer from asthma so the effect could be tangible. However, the results of measurements of the air in the city during the Games showed otherwise.

The University of Leicester in partnership with Surrey Satellite Technology developed instruments to measure London’s air quality during the 2012 Olympic Games. The instruments are called CityScan and for the three weeks of the Games, they specifically measured emissions of (NO2), a toxic air pollutant released from vehicle engines and fossil fuel power plants.

“Air quality affects human health and ecosystems and the Olympics was a huge urban air quality experiment. We wanted to use CityScan during it because of the huge surge in activity around London,” said Dr Paul Monks, a professor of atmospheric chemistry at the university. He was also a member of the group responsible for installing and monitoring the instruments.

They installed the three CityScan units on building rooftops around the city before the Games began. The instruments rotated in a full circle, capturing thousands of digital images that, when stitched together from the three units, create a 3-D panorama of London’s sky from about 40m to a bit less than 3.2km above the ground.

Monks says that different types of molecules absorb different wavelengths of light which in turn create a unique type of fingerprint that is used to identify particular pollutants. Nitrogen dioxide which is a brown gas absorbs red light. The CityScan instruments measured and recorded the amount of sunlight absorbed by NO2 in the atmosphere. If the instrument detects low levels of NO2’s wavelength, the more of it is present in the air.

What the group from the University of Leicester found thus far is remarkably surprising if not unexpected by some. During the 17 days of the Games, when more than 100 000 foreign visitors came to London, atmospheric NO2 actually seems to have gone down.

“Before the Games began, I predicted pollution would be better because many Londoners and workers stayed out of the city,” Monks says. “I was right.” He attributes the lower NO2 pollution levels to the widespread use of public transportation during the Games, a far more efficient means of transport. “The overall NO2 emission pattern changed because the transport pattern changed,” he says.

Good weather conditions also assisted in alleviating the burden on the air. There was an almost constant flow of fresh air off the Atlantic Ocean instead of stagnant continental systems creeping over from the European mainland. “It was really very good pollution-wise,” Monks says. “These factors combined to keep pollution down to allow the athletes to perform at their best.”

According to the World Health Organisation, urban atmospheric pollution may cause the deaths of 1.3 million people per annum. However, the European Environment Agency has monitored trends and reports that the skies above the EU have grown less burdened with decreasing concentrations of the major airborne pollutants since 1990, thanks to tighter regulations and better technology. Nitrous oxides levels, which include NO2, have fallen by 47% since 1990. This is not true for the UK. The government has found that the reduction in NO2 has levelled off in recent years. Their 2011 report states that “urban background concentrations of NO2 monitored in inner London, and at roadside locations, have exceeded the annual limit value since 2000.”

The air quality group is hoping CityScan will help officials and regulators get a better handle on NO2 emission patterns by bridging the resolution gap that exists between distant remote-sensing satellites and point measurements attained by getting up close and personal with local pollutant sources.

Source: txchonologist.com