Euro VI diesel emission norms can avert nearly 174,000 premature deaths


Under the current diesel emission norms, there is a wide gap between on-road NOx emissions and certification limits.

Despite tighter nitrogen oxides (NOx) emission norms for diesel cars, buses and trucks in several countries, the actual amount of NOx emitted by diesel vehicles is far more during on-road driving conditions than under laboratory testing carried out at the time of certification. As a result, the excess NOx emitted over certification limits caused nearly 38,000 premature deaths in 2015 in the European Union, China and India; India alone had 9,400 deaths due to excess NOx emissions. Over and above the deaths caused by excess NOx emissions, increased air pollution from diesel NOx caused 107,600 premature deaths globally in 2015.

Diesel vehicles in the 11 major markets (Australia, Brazil, Canada, China, the EU, India, Japan, Mexico, Russia, South Korea, and the U.S.) emitted 13.2 million tonnes of NOx under on-road driving conditions, which is 4.6 million tonnes more than the vehicles’ performance under official laboratory testing. Compared with certification testing, the average on-road NOx emission is 2.3 times higher for light-duty diesel vehicles and 1.45 times the limit for heavy-duty diesel vehicles. Diesel vehicles sold in the 11 markets account for about 80% of global sales.

Adopting and enforcing the stricter Euro VI emission norms could “nearly eliminate” on-road diesel-related NOx emissions and avoid nearly 174,000 premature deaths in 2040, says a study published in Nature on May 15. NOx is a key contributor to outdoor air pollution in the forms of ground-level ozone and fine particulate matter of less than 2.5 micrometre size (PM2.5).

Under the current Euro IV diesel emission norms, there is a wide gap between on-road NOx emissions and certification limits. The excess NOx emissions coming from diesel vehicles gained worldwide attention when 11 million Volkswagen vehicles that contained defeat devices that controlled emissions only at the time of emission testing became known. But what is less known is that the current certification procedure adopted for diesel cars, buses and trucks “legally permits higher” vehicle emissions under normal driving conditions than the certification limits.

Euro VI emission norms have in-service testing, in-use emission monitoring, expanded driving conditions and independent verification.

Heavy diesel vehicles accounted for 86% of on-road emissions and over 75% of excess on-road diesel NOx emissions in 2015, about 90% of which is from China and India, the EU, Brazil and the U.S. In the case of diesel cars, the on-road emissions were 130% more than the certification limits.

IIT Kanpur finds more aerosol in the atmosphere produces heavier, widespread rainfall


Prof. Sachchida Tripathi (left) and Chandan Sarangi studied satellite data spread over 12 years.

Contrary to the general notion that pre-monsoon aerosol loading results in decrease in seasonal rainfall, a long-term (2002-2013) satellite observational study and model-based analysis by researchers from the Indian Institute of Technology (IIT) Kanpur has found that higher aerosol loading results in delayed but more rainfall over Central and Northern India. Higher aerosol loading changes cloud properties in terms of size (both height and width) and microphysics, which results in more rainfall. The results were published in the journal Atmospheric Chemistry and Physics.

Fourteen microns is the agreed raindrop size and until it reaches this size the growth of droplets in the cloud is primarily driven by condensation. When aerosol particles are higher, the number of nucleation sites increases resulting in far too many number of droplets. Under such circumstances, it takes time for the droplets to grow in size through condensation.

More but smaller droplets

“There is an increase in the condensation of water vapour into cloud droplets as the number of aerosol particles increases. But there is a reduction in radius of the drops formed near the cloud base,” says Prof. Sachchida N. Tripathi, from the Department of Civil Engineering, IIT Kanpur and the corresponding author of the paper. This results in delay in the onset and efficiency of the condensation process.

“Although genesis of cloud systems is influenced by various meteorological parameters, aerosols are capable of strongly modifying the cloud structure, dynamics and composition during Indian summer monsoon,” says Chandan Sarangi from the Department of Civil Engineering, IIT Kanpur and the first author of the paper. “Once cloud starts forming due to convection, the presence of more aerosol particles tend to modify the warm phase microphysics as well as ice phase microphysics.”

Two forces — gravity and updraft (vertical velocity) — tend to act on droplets. Under high aerosol loading, rather than falling down as raindrops, the smaller droplets tend to rise upwards in convective atmosphere due to updraft. As the droplets are lifted up they tend to cross the freezing level and turn into ice particles. The process of water droplets turning into ice particles releases more latent heat of freezing and further invigorates the cloud. “Ice turns into water by absorbing heat. Similarly, when water turns into ice it gives off heat. This release of heat further fuels the convection process and the clouds grow taller,” says Sarangi.

Taller clouds

“Satellite data showed that clouds are getting taller and wider under high aerosol loading,” says Prof. Tripathi. As the height of clouds increases, the ice particles generated at top of the cloud come in contact with numerous water and ice particles and become bigger in size. This results in more ice mass in the cloud and eventually more rainfall when the ice particles fall down due to gravity. “There is a delay in the onset of rainfall but once it starts raining it covers a wider area and may be heavier rainfall as well,” Prof. Tripathi says.

In the absence of cloud, aerosol particles tend to absorb solar radiation and this leads to warming or less decrease in temperature with height. As a result, there is suppression of convection leading to further suppression of cloud formation.

As clouds reflect radiation, an increase in aerosol concentration leads to further increase in reflected radiation from the cloud. Also, as the cloud top increases in height, the emitted long wave decreases. “An unit increase in aerosol concentration leads to twice more cooling under cloudy conditions,” Prof. Tripathi says.

Till now scientists have shown that presence of more aerosol in pre-monsoon season may lead to reduction in total monsoon rainfall due to aerosol-solar radiation interactions. “But in our study we looked at co-located measurement of aerosol, cloud and rainfall system. The aerosol-cloud microphysical feedback suggests that higher aerosol loading can enhance the strength of convective rainfall and increase the frequency and intensity of extreme rainfall during Indian summer monsoon,” says Sarangi.

Published in The Hindu on April 22, 2017

IIT Kanpur unravels brown carbon’s effect on atmospheric warming


(From left) Shamjad, Prof. Tripathi and Navaneeth Thamban of IIT Kanpur found brown carbon increases atmospheric warming by absorbing 30 per cent of light

The effect of biomass burning in increasing the atmospheric aerosol and in turn the atmospheric warming through light absorption has been clearly highlighted in a study carried out by a team of researchers from the Indian Institute of Technology (IIT) Kanpur. While the role of black carbon produced by biomass burning in increasing the atmospheric warming has already been well established, the latest study highlights the role of the less known role of brown carbon.

Brown carbon produced by biomass burning has higher light absorption capacity and, therefore, higher capability to increase atmospheric warming. Compared with earlier studies carried out in the U.S, light absorption at 365 nm was found to be five times higher in Kanpur, which has a high biomass burning area. Also, brown carbon accounts for about 30 per cent of light absorption in Kanpur. The results were published on November 24 in the journal Scientific Reports.

“What is seen in Kanpur can be generalised for the entire Indo-Gangetic Plain because the sources of aerosol remain the same throughout the region,” says P.M. Shamjad from the Department of Civil Engineering, IIT Kanpur and the first author of the paper.

“Based on 50 days of measurement (December 23, 2014 to February 24, 2015) we were able to clearly apportion the amount of light absorption by different carbonaceous aerosols. Though brown carbon is 10 times more than black carbon in terms of mass, the absorption capacity of black carbon is 50 times more than brown carbon,” says Prof. S.N. Tripathi from the Department of Civil Engineering, IIT Kanpur and the corresponding author of the paper.

As a result, up to about 70 per cent of light absorption during 24 hours is by black carbon. Brown carbon (when present independently) has nearly 15 per cent potential to warm the atmosphere by absorbing light. Additionally, depending on the spectrum of light, the light absorption capacity of brown carbon is 15-30 per cent when present as a coating (shell) over a black carbon core. “This is because the brown carbon coating behaves like a lens and focuses light towards the black carbon core,” says Shamjad.

The lensing (concentration of light on the core) is dependent on three parameters — ratio of the diameter of the total to the diameter of the core, wavelength of light and the scattering or absorbing property of the coating. “When you have an absorbing coating less light reaches the core. But when the coating is non-absorbent, light gets scattered and more light reaches the core. This leads to more overall light absorption and, in turn, more atmospheric warming,” says Prof. Tripathi.

Unlike at 405 nm (near UV), at 781 nm (near infrared), the lensing becomes predominant as the absorption capacity of the brown carbon coating is non-existent. This is because during daytime, photo bleaching of the brown carbon by sunlight creates a new compound that is no longer able to absorb sunlight.

“The contribution of lensing to light absorption goes up to nearly 35 per cent. This has very serious implications on atmospheric warming,” Prof. Tripathi says.

Published in The Hindu on November 26, 2016

Non-communicable diseases killed more Indians in 2015



Cardiovascular diseases were the leading cause of deaths in males and females in India in 2015. And high systolic blood pressure was the number one risk factor.

In 2015, India, like other developed countries, had more number of deaths caused by non-communicable diseases. In the case of males, deaths due to non-communicable diseases (3.6 million) were more than double that caused by communicable diseases (1.5 million), while it was nearly double in females (2.7 million due to non-communicable diseases and nearly 1.4 million deaths due to communicable diseases, neonatal, and nutritional diseases). Globally, 70 per cent (40 million) of deaths in 2015 were due to non-communicable diseases.

Cardiovascular diseases were the leading cause of death in both sexes in India — 1.6 million in males and 1.1 million in females. The next biggest cause of deaths was chronic respiratory diseases — 0.68 million in males and 0.5 million in females.

These are some of the Global Burden of Diseases results (here, here, here, here, here, here,  and here) published in seven papers in The Lancet on October 6.

Injuries killed 0.6 million males and 0.3 million females in 2015 alone. India had the highest number of suicide deaths in the world last year, with nearly 132,000 deaths in men and over 76,000 deaths in women. At 0.36 and 0.31 million, neonatal disorders killed nearly equal number of males and females. The other leading causes of deaths last year in both sexes were ischemic stroke, haemorrhagic stroke, TB, lower respiratory infections and diarrhoea.

India had the highest number of suicide deaths in the world in 2015.

Slower reduction in MMR

Along with Nepal and Bhutan, India has registered a slower reduction in maternal mortality rate (MMR). The MMR was reduced by a little over 50 per cent in 25 years (1990 to 2015), from over 130,000 deaths in 1990 to nearly 64,000 deaths in 2015.

In 2015 alone, the number of under-5 deaths in India was 1.26 million. The number of stillbirths alone was 0.53 million. “India recorded the largest number of under-5 deaths in 2015, at 1.3 million (1.2–1.3 million), followed by Nigeria (726,600) and Pakistan (341,700),” says a paper in The Lancet. Neonatal pre-term birth complications, lower respiratory infections, diarrhoeal diseases and measles were some of the leading causes of under-5 mortality.

The rate of under-5 deaths was 48.9 deaths per 1,000 live births. For every 1,000, live births there were 29.06 neonatal deaths (0-27 days after birth), 20.25 stillbirths, 11.74 post-neonatal (28 days to 1 year) deaths, and 8.80 deaths during the 1-4 years.

The Janani Suraksha Yojana conditional cash transfer programme was established when increasing number of women sought reproductive health services. “[The programme] has been successful at increasing reproductive health-care services, but even despite its popularity this programme has not been as effective at reaching poor rural women, the sociodemographic group that is already at highest risk of adverse pregnancy outcomes,” a paper notes.

Leading risk factors

For both sexes, the leading risk factors are high systolic blood pressure, fasting plasma glucose, ambient particulate matter, household air pollution, and unsafe water. According to The Lancet, smoking is a bigger risk factor for Indians than even cholesterol and iron deficiency. Childhood under-nutrition and lack of whole grains figure in the list.

Iron-deficiency anaemia is the leading cause for years lived with disability in the case of India, followed by lower back and neck pain, sense organ diseases, and depression.

Published in The Hindu on October 6, 2016

Thanks to air pollution, magnetic particles found in the brain


Magnetite nanoparticles are toxic to the brain tissue as they generate reactive oxygen species.

The effects of air pollution on human health has gone up by a few notches with the discovery of large number of rounded magnetite nanoparticles of about 18 nanometres in diameter (and maximum of 150 nm) in the frontal cortex tissue of the brain of 37 people. The people studied were 3-92 years old and lived in Mexico City and Manchester, U.K. The results are published today (September 6) in the Proceedings of the National Academy of Sciences. 

This is the first time rounded magnetic nanoparticles occurring along with other transition metals, such as platinum, nickel, and cobalt have been reported in the brain of human beings.

Airborne particles less than 200 nanometres can enter the brain directly through the olfactory nerve. The nanoscale magnetite particles can respond to external magnetic fields and are toxic to the brain tissue as they have been implicated in the generation of reactive oxygen species. Enhanced reactive oxygen species production in the brain is casually linked to neurogenerative diseases such as Alzheimer’s.

Magnetite particles are ubiquitous in airborne-particulate matter and are caused due to combustion of iron-rich particles and friction-heating (brake pads). “Magnetite can arise from combustion of many types of organic matter, depending on heating temperature and atmosphere, and source of iron content,” they write. Besides, industrial and vehicles, open fires or poorly sealed stoves used for cooking and/or heating can produce magnetite nanoparticles. The combustion-derived magnetite particles can range in size from less than 5 nanometre to 1 micrometer.

“Increased metals content and Alzheimer’s disease neuropathological hallmarks have been found in young human brains exposed to high airborne particulate matter PM2.5 concentrations in Mexico City,” the write. Since only about 5 per cent of Alzheimer’s is directly inherited, other factors such as environmental factors and/or gene/environment interactions may be playing a huge role in initiating and/or promoting Alzheimer’s.

But it yet to be firmly established that magnetite from air pollution can indeed be a critical factor in the development of Alzheimer’s. Particularly because more number of cases should be seen and at an early ages in places where magnetite pollution in air is more. It is also not clear yet whether size, number, mineralogy and associated chemical species of particulate matter contributes most to toxic effects.

Emissions from biomass burning cross the Himalayas

Emissions from biomass burning - R. Prasad

Contrary to popular belief, pollutants do manage to cross the Himalayas. – Photo: R. Prasad

Contrary to the general assumption that the southern slopes of the Himalayas act as a barrier and effectively block the transportation of pollutants from India and other parts of South Asia, a study published a couple of days ago in the Nature Group journal Scientific Reports finds sound evidence to prove otherwise.

Aerosols have been found to rise and cross the entire range of the Himalayas. So much so that studies conducted in the northern slope of the Himalayas at an elevation of 4,276 MSL could find markers distinctive of pollution arising from India and other regions of South Asia.

Local meteorological conditions and regional atmospheric flow process have been the two major factors enabling the pollutants to cross over, notes Zhiyuan Cong, the first author of the paper from the Institute of Tibetan Research, Chinese Academy of Sciences, Beijing.

The culprit

The organic acids present in the aerosols serve as a unique fingerprint in identifying the source of pollution. In this case, the dicarboxylic acids served as a fingerprint.

Though dicarboxylic acids can be produced by biomass burning, vehicular exhausts and cooking (primary source), as well as atmospheric photooxidation (secondary source), the researchers were able to pinpoint the source as biomass burning.

Levoglucosan is a specific marker of biomass burning — it is “produced through the pyrolysis of cellulose during the combustion process,” Dr. Cong notes. Another unique marker of biomass burning is the water-soluble potassium. Both the markers showed strong positive correlation with dicarboxylic acids thereby confirming biomass burning as the source of pollution.

Though the pollutants were found to reach the northern slopes of the Himalayas during all the seasons — pre-monsoon, monsoon, post-monsoon and winter seasons — the amount of aerosol found peaked during pre-monsoon. This, according to them, is one more indicator of biomass burning as the source.

Agricultural burning and forest fires along the southern Himalayan foothills and the Indo-Gangetic Plain reach a high during the pre-monsoon period. That probably is the reason why the amount of biomass burning marker found peaked during the pre-monsoon time.

Dr. Cong attributes the local topographic relief of the Himalayas playing an important role in allowing the pollutants to cross the mountains and reach the northern slopes.

The up-valley wind during daytime, being maximum in the afternoon, helps in pushing the pollutants to higher altitude. On the northern slopes, a down-valley wind is prevalent during the same time. The combination of the up-valley wind in the southern slopes and down-valley wind in the northern slopes allows the accumulation of aerosol on the glacier surfaces.

“Acting as efficient channels of south-to-north air flow, the mountain valleys could allow the air pollutants to easily penetrate throughout the Himalayas,” the authors write.

“Regardless of where the pollutants come from, the study has provided compelling evidence that they are due to biomass burning. We must step up the global effort to drastically cut down biomass burning as much as we can,” Veerabhadran Ramanathan, an atmospheric scientist at the Scripps Institution of Oceanography in La Jolla, California, who is unconnected with the study, told Nature.

Published in The Hindu on April 16, 2015