The grey area over air pollution
Statistics recently released by the World Bank claim the UAE has the highest mean average of air pollutants of any other country on the list, including China and India. But how have these figures been gathered, and are they reliable?
Air pollution is a murky business. Every year new rankings are released, often with conflicting results that leave some people scratching their heads.
Last month the World Bank released its Little Green Data Book, with more than 230 pages of numbers broken down by environmental topic and geography.
The figure that grabbed the world’s attention was the amount of very small particulate matter (PM) in the air we breathe. Measured by size, PM is the tiny particles of sand, chemicals or dust that float around the air, a lot of it invisible to the naked eye.
It is associated with heart disease and attacks, cancers and strokes. In its smallest form it is known as PM2.5. A PM10 is less than the width of a human hair.
“Particulate matter is particularly important because it is linked to premature mortality,” says professor Ranjeet Sokhi, director of the Centre for Atmospheric and Instrumentation Research (Cair) at the University of Hertfordshire in the UK.
“There is mounting evidence that finer particles, represented by PM2.5, are particularly hazardous to health, although coarse fractions are also of health importance.
“While the focus has been on people with pre-existing respiratory or cardiac health problems, new evidence is showing links with diabetes, neurological development in children and neurological disorders in adults.”
According to the World Bank report, the UAE has an annual mean of 80 PM2.5 micrograms for each cubic metre. This is higher than any other listed country, including China and India, and eight times the World Health Organisation’s (WHO) guidelines.
To those that have visited cities such as New Delhi in India and Beijing in China, the figures seem hard to believe. A blanket of grey hangs above those cities and the toxic contents of the air are almost palpable.
China’s reading, which excludes Hong Kong and Macau, was 73, seven points lower than the UAE. India’s reading was only 32.
The data for the report was provided by the Institute for Health Metrics and Evaluation at the University of Washington, from 2010.
In response to the report and its worldwide coverage, Fahad Hareb, director of air quality at the Ministry of Environment and Water, said pollution levels in the UAE were safe for residents and that the World Bank figures were inaccurate.
Mr Hareb said the ministry was trying to find out what kind of data-gathering model the institution had used.
The WHO released its own rankings last year, featuring data from more than 1,600 cities in 91 countries and producing a very different result.
In this measure, the city with the worst level – of 153 PM2.5 micrograms for each cubic metre of air – was New Delhi.
In fact, Indian cities occupied 10 of the top 15 spots.
The worst offending city in the Middle East was Khorramabad, in western Iran, which is the agricultural capital of the Zagros Mountains region.
The next Middle East city to feature on the extensive list was Doha, Qatar, with PM2.5 levels of 93 micrograms per cubic metre.
Al Gharbia in the UAE, took slot number 51 and Abu Dhabi number 55, with a reading of 64.
The aim of the database, which WHO calls the largest of its kind, was “not to rank cities or countries but to reflect the monitoring efforts undertaken in those countries”.
A report last year by the Environment Agency – Abu Dhabi, or Ead, offered a breakdown of the sources of PM2.5. It said between 54 and 67 per cent came from man-made sources.
Almost half of these particles were a secondary aerosol of sulphate and ammonia, from oil production and refining. A quarter were from mineral dust; between 13 and 15 per cent were from traffic, and 11 per cent originated in industry and shipping.
“PM2.5 is monitored in Abu Dhabi due to its effect on public health, but there are no established federal limits,” Ead said.
“However, it is known that the pressures on air quality are increasing with rising transport, water and electricity demand, expansion of the oil and gas sector, industrialisation, and increase in construction and demolition activities.”
Prof Sokhi says the desert environment in the UAE means the air will always contain significant amounts of windblown dust, especially during dust storms.
“This dust does have a health burden despite being naturally occurring,” he says. “It is likely that the most effective way of tackling this natural burden is through education aimed at encouraging people to stay indoors when there are high levels of PM in the air.”
Even estimates about the concentration of causes in cities and countries do not seem to explain the difference in figures.
As of March this year there were about 9 million registered vehicles on the roads in New Delhi. The most recent government figures also revealed there were more than 160 million registered motor vehicles in the country.
Figures from the Statistics Centre Abu Dhabi’s 2014 year book show there were 785,076 motor vehicles registered in the emirate in 2011. No more recent information is available.
Comparing air quality even within a single country is complex, says Prof Sokhi.
“In other areas, natural sources can be important as in the case of cities near desert areas. Meteorological processes play a key role too, for example photochemistry leading to urban smog and high concentrations when anticyclonic conditions prevail with stable atmospheric conditions.
“Similarly, differences in precipitation and seasonal changes will affect air pollution levels. The combination of these effects will be very different for cities such as London and Abu Dhabi.”
A recent study by United States researchers revealed that meeting the WHO’s air quality guidelines could prevent 2.1 million deaths a year.
The public health researchers said outdoor particulate air pollution resulted in 3.2 million premature deaths each year, more than the combined impact of HIV-Aids and malaria.
The calculations were specifically based on numbers for PM2.5, taken from the Institute for Health Metrics and Evaluation’s Global Burden of Disease report. Author Joshua Apte, of the Cockrell School of Engineering at the University of Texas, said the results should be used to shape better public health policies.
According to the study, published in Environmental Science and Technology magazine, if air pollution levels remain the same as they are today, deaths per capita from air pollution will increase 20 to 30 per cent over the next 15 years in India and China, the two countries marked as having the worst levels.
The regional office of the WHO last year said there were 1,450 estimated premature deaths in the UAE in 2010 resulting from ambient PM pollution.
Some other Middle East countries had much higher figures, with Saudi Arabia at 8,550 and Iran at 32,288.
In January 2013, the US embassy in Beijing recorded levels of PM2.5 as high as 526 micrograms per cubic metre. So high it is known as “beyond index”.
Airlines were forced to cancel flights because the visibility was so bad and the city’s inhabitants were warned not to go outside.
The city has taken a number of measures to reduce its air pollution and the premature deaths resulting from it. They include limits on car emissions and coal burning, and yearly quotas for local governments and individuals. There are also fines for those breaking the rules.
“A number of measures are already in place in UAE,” says Prof Sokhi. “Measures which improve the quality and which reduce the quantity of fossil fuels burnt in the UAE and its cities should be considered.”