NASA maps worldwide changes in NO2 levels
Air quality laws and regulations appear to have helped reduce NO2 levels in Western Europe and the USA over the last decade
A world map showing air pollution trends over the last decade has been produced to display the human footprint on air quality.
Map showing changes in NO2 levels from 2005-2014, blue denoting decreased emissions and red increased emissions (Image: NASA’s Goddard Space Flight Center – click to enlarge)
The map, produced by NASA, shows changes in nitrogen dioxide concentrations — a common emission from cars, power plants and industrial activity — over the past decade.
It suggests that more recent air quality laws and regulations have had a considerable impact on NO2 in the USA and Europe.
A NASA science team led by Bryan Duncan, an atmospheric scientist at the Goddard space flight centre, made observations made from 2005 to 2014 across various regions and 195 cities worldwide using the ozone monitoring instrument on NASA’s Aura satellite.
Two types of data are visible on the map, with blue and green colours indicating where the concentration of tropospheric nitrogen dioxide has fallen, and orange and red demonstrating areas where levels have increased.
Trends
According to NASA, previous studies using satellites at lower resolutions missed air quality variations over short distances, but this new space-based view “offers consistent information on pollution for cities or countries that may have limited ground-based air monitoring station” and tells a “unique story” for each region.
To look for explanation of trends in nitrogen dioxide levels, the researchers compared the satellite record to information about emission control regulations, national gross domestic product (GDP) and urban growth.
Mr Duncan said: “With the new high-resolution data, we are now able to zoom down to study pollution changes within cities, including from some individual sources, like large power plants.”
Findings showed that the United States and Europe are among the largest emitters of nitrogen dioxide.
However, both regions also showed the most dramatic reductions during the ten years. Nitrogen dioxide has decreased from 20% to 50% in the United States and as much as 50% in Western Europe.
Map showing changes in NO2 levels in 2014, with red signifying higher emissions and blue lower emissions (Image: NASA’s Goddard Space Flight Center – click to enlarge)
Researchers concluded that the reductions are largely due to the effects of environmental regulations that require technological improvements to reduce pollution emissions from cars and power plants.
China
Meanwhile China saw an increase of 20%-50%, which is attributed to increased manufacturing and the South African region had the highest nitrogen dioxide levels in the southern hemisphere, although the map shows a complex situation playing out between cities and neighbouring industrial areas.
In the Middle East, increased nitrogen dioxide levels since 2005 in Iraq, Kuwait and Iran likely correspond to economic growth in those countries. However, in Syria, nitrogen dioxide levels decreased since 2011, most likely because of the civil war, which has interrupted economic activity and displaced millions of people.
The blue on the first map shows the decreasing trends in NO2 concentrations from 2005-14. The second map (according to NASA’s website – your label is incorrect) shows NO2 levels in 2014. The red areas indicated that NO2 levels remain unacceptably high. Table 9.2 of the European Environment Agency’s ‘Air quality in Europe — 2015 report’ shows an estimated 37,800 premature deaths from PM2.5 pollution in the UK and 14,100 from NO2.
A comprehensive review of the tax incentives to encourage diesel vehicles concluded that they were totally misguided – “global warming has been negatively affected, and air pollution has become alarming in many European locations†– see references at: bmj.com/content/350/bmj.h2757/rr-0
It will take many years and millions of pounds to reverse the mistake of encouraging diesel vehicles, so it makes sense to tackle the other major and increasing source of PM2.5 emissions – home wood burning, which accounted for 17% of PM2.5 emissions in 2013, only marginally less than the 18% from all road transport.
Current misguided policies are allowing the problem to get worse. The average log-burning stove permitted in smokeless zones emits more PM2.5 per year than 1,000 petrol cars, with estimated annual health costs of thousands of pounds per stove per year. Buyers often think log-burning stoves are good for the environment, but in reality they create alarming levels of PM2.5 pollution and their methane and black carbon emissions increase the risk of exceeding 2 degrees of global warming.
Dr Gary Fuller studied sources of PM2.5 pollution in the UK, commenting: “Home wood burning needs to be addressed before more people invest in stoves or make open fires a feature in their living rooms.†Given estimates of over twice as many premature deaths from PM2.5 pollution as NO2 pollution, PM2.5 pollution should also be tackled as quickly and cost-effectively as possible.
With estimated health costs of thousands of pounds per log-burning stove per year, and much greater contribution to global warming than other forms of heating, a good first step would be to implement the UN Environment program recommendation of phasing out log-burning stoves in developed countries such as the UK. Perhaps Air Quality News could help raise awareness of this important issue?