Ozone pollution in India kills enough crops to feed 94 million in poverty

September 4, 2014
Smog in India. Ozone, the main component of smog, is a plant-damaging pollutant formed by emissions from vehicles, cooking stoves and other sources. New research shows that ozone pollution damaged millions of tons of wheat, rice, soybean and cotton crops in India in 2005. Credit: Mark Danielson/Flickr

In one year, India's ozone pollution damaged millions of tons of the country's major crops, causing losses of more than a billion dollars and destroying enough food to feed tens of millions of people living below the poverty line.

These are findings /of a new study that looked at the agricultural effects in 2005 of high concentrations of ground-level ozone, a plant-damaging pollutant formed by emissions from vehicles, cooking stoves and other sources. Able to acquire accurate crop production data for 2005, the study's authors chose it as a year representative of the effects of ozone damage over the first decade of the 21st century.

Rising emissions are causing severe in some of India's most populated regions. Pollution in Delhi, the nation's capital, has reached levels comparable to Beijing, one of the most polluted cities in the world, according to India's Air Monitoring Center.

The main component of smog, ozone at ground level can cause leaf damage that stifles plant growth, injuring and killing vegetation. There are currently no air quality standards in India designed to protect agriculture from the effects of ground-level ozone pollution, according to the new study. Ground-level ozone is formed when nitrogen oxides, carbon monoxide and volatile organic compounds react with sunlight after the chemicals' release from vehicles, industry, or burning of wood or other plant or animal matter.

According to the new study published Aug.14 in Geophysical Research Letters, a journal of the American Geophysical Union, surface ozone pollution damaged 6 million metric tons (6.7 million U.S. tons) of India's wheat, rice, soybean and cotton crops in 2005.

India could feed 94 million people with the lost wheat and rice crops, about a third of the country's poor, according to Sachin Ghude, an atmospheric scientist at the Indian Institute of Tropical Meteorology (IITM) in Pune, India and lead author of the new study. There are about 270 million Indians that live in poverty, according to the study.

Wheat – one of the country's major food sources – saw the largest loss by weight of the four crops studied in the new paper, with ozone pollution damaging 3.5 million metric tons (3.8 million U.S. tons) of the crop in 2005. Another major food source, rice, saw losses of 2.1 million metric tons (2.3 million U.S. tons), according to the new study.

Cotton – one of India's major commercial crops—lost more than 5 percent of its 3.3 million metric ton (3.6 million U.S. tons) annual output in 2005, costing the country $70 million, according to the new research.

Policy implications

Ghude said the new paper, which is the first to quantify how much damage India's ozone pollution has caused the country's major crops on a national level, could help policymakers craft new ozone pollution standards.

It could also help India, a country with a high rate of poverty, as the country implements a new law that subsidizes grain for two-thirds of the country's residents, he said. The new food security bill requires the country to provide 61.2 million metric tons (67.5 million U.S. tons) of cereal grains – that include wheat and rice – to India's poor each year at a subsidized rate. The new study found that the 5.6 million metric tons (6.2 million U.S. tons) of wheat and rice lost to ozone pollution was equal to 9.2 percent of the new law's subsidized cereal requirement.

"The (amount of lost wheat and rice) are what surprised me," said Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography, at the University of California San Diego and a co-author of the new study.

Under the new law, residents who qualify to receive cereal at the subsidized rate can purchase 60 kilograms (132 pounds) of grain per year. Based on these numbers, the 5.6 million metric tons (6.2 million U.S. tons) of wheat and rice lost could therefore feed 94 million people in India, according to the study.

Calculating ozone damage

The researchers calculated the amount of total crop damage from ozone pollution by comparing emissions estimates from 2005 with data about how much ozone each of the four crops could withstand. Plants start to exhibit damage when they are exposed to ozone levels that reach 40 parts per billion or above, according to previous research.

A computer model used by researchers calculated ozone levels during crop growing seasons that were more than 40 to 50 parts per billion over most of the country. The team ran the model with different emissions estimates to come up with an average amount of each crop that was lost due to ozone pollution.

India's economic loss from ozone's harm to crops amounted to $1.29 billion in in 2005, the study found. Declines in rice and wheat crops made up the majority of the loss, accounting for a combined $1.16 billion in losses, according to the new research.

Despite air quality standards passed in the 1980s to curb industrial and vehicle emissions, cities in India are some of the most polluted in the world, according to the World Health Organization. The number of vehicles on the road in India has nearly tripled in the past decade, with 130 million vehicles on the road in 2013 compared to 50 million in 2003, according to the International Council on Clean Transportation.

Long-term measurements of surface ozone over India – measured on the ground or by aircraft—are not available, making it difficult to get a clear picture of how in the country have changed, Ghude said. But satellite-based studies show ozone has increased over the country in the last two decades, Ghude said. Warmer temperatures that are expected with climate change could also increase ground-level ozone, according to previous research.

Ramanathan said that unlike most studies, which look at the effect emissions will have on agriculture decades in the future, the new study examined how ozone emissions are already affecting crops in India. He said the new study could help spur interest in the issue and help policymakers enact new air quality standards or mandate use of new technology to cut emissions.

Explore further: Climate change and air pollution will combine to curb food supplies

More information: onlinelibrary.wiley.com/doi/10.1002/2014GL060930/abstract

Related Stories

Monitoring ground-level ozone from space

August 29, 2011

Satellite views of the Midwestern United States show that ozone levels above 50 parts per billion (ppb) along the ground could reduce soybean yields by at least 10 percent, costing more than $1 billion in lost crop production, ...

Recommended for you

Sea ice extent sinks to record lows at both poles

March 22, 2017

Arctic sea ice appears to have reached on March 7 a record low wintertime maximum extent, according to scientists at NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. And on the opposite ...

Under the dead sea, warnings of dire drought

March 22, 2017

Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans—a possible warning for current times. Thick ...


Adjust slider to filter visible comments by rank

Display comments: newest first

4.2 / 5 (5) Sep 04, 2014
This is a very important study. Not enough people are aware of how damaging ozone is to annual crops, and in fact the problem is far worse even than depicted in this research for numerous reasons.

1. Damage is cumulative, so that ozone is causing longer-lived species such as trees and shrubs to die prematurely all over the world.
2. Ozone decreases the ability of vegetation to ward off biotic attacks, leading to epidemics of insects, disease and fungus on every species you can imagine, globally. This is a far more pernicious effect of ozone than the direct reduction in yield production referred to in the study.
3. Even before a reduction in growth or injury to foliage is observed, root systems suffer a depletion. This increases vulnerability to drought and windthrow.
4. The loss of wild plants is having ripple effects throughout the natural ecosystem, affecting insects, birds, and mammals.

4 / 5 (4) Sep 04, 2014
I should have added perhaps the very worst effect of ozone (in addition to landslides, wildfires, and falling trees killing people, crushing houses and cars, and dragging down power lines) which is that the loss of a major CO2 sink will greatly accelerate climate change.
5 / 5 (4) Sep 04, 2014
Careful WitsEnd. Mentioning climate change will bring the troll deniers to pollute the thread.

But surely, even the most head-up-his-arse climate change denier must admit that pollution is bad for people, animals and plants, and that asia and India in particular has a serious and growing pollution problem.
1 / 5 (6) Sep 04, 2014
This is odd because most ozone is emitted by trees. How are plants harmed by ozone? Ozone does not affect photosynthesis.
5 / 5 (2) Sep 04, 2014
I stand corrected. There is clearly no lower limit on denier IQ.
1 / 5 (2) Sep 04, 2014
Imo the inclusion of a comparison like'...enough food to feed tens of millions of people living below the poverty line.' is unwise. I don't deny pollution etc. but feeding India's millions is/has been a economic problem too. @NOM I think that the article has enough weight without that comparison which only allows trolls to engage.
Thorium Boy
1 / 5 (3) Sep 05, 2014
The more they concentrate on controlling non-pollutants like C02, the less they spend on REAL pollution control for C0, sulfur dioxide, nitrous oxides, diesel particulates, etc. Indian streets are still filled with 2-stroke vehicles and vehicles with ZERO pollution-control devices and they still burn raw coal and wood for cooking. China isn't much better, if technologically more advanced.
3 / 5 (2) Sep 05, 2014
4marshall claimed
This is odd because most ozone is emitted by trees. How are plants harmed by ozone? Ozone does not affect photosynthesis.
Well it would be odd a relatively powerful oxidising agent such as Ozone gets out of a plant cell - ostensibly produced from photosynthesis - without reactions, of what reduction in concentration, before it reaches the outside air ?

So, where is the evidence for your claim ?

You do realise that arbitrary claims aren't helpful and a specific issue such as ozone production should be well known, so link us to a paper or biochem study that YOU base your post upon ?
3 / 5 (2) Sep 05, 2014
Thorium Boy muttered oddly
The more they concentrate on controlling non-pollutants like C02, the less they spend on REAL pollution control for C0, sulfur dioxide, nitrous oxides, diesel particulates, etc.
Who is this 'they' ?

My understanding is CO & other emissions from cars & power plants are managed under various guidelines already Eg Cats.

Are you claiming the staff bureaucracy in various governments will be less paid or even pulled off their duties so these people must manage CO2 ?

Are there not enough people skilled in these areas to go around ?

This definitely is not the case where I currently reside in Western Australia...

What makes you imagine CO2 is not polluting, ever heard of Paracelsus - father of pharmacology ?

At ~3% we die, at current level some (food) plants gradually shift equilibrium to produce cyanogens & become poisonous - this has been happening for decades in Africa with Cassava, crops such as Clover also suffer the same biochemistry adaptation !

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.