India ranks among the five countries most vulnerable to climate change and air pollution, a first-of-its-kind research assessing the combined risks of the two factors said recently.

China also makes the list. The world’s two fastest developing economies have witnessed a spurt in particulate matter induced air pollution levels in the past two decades and a simultaneous increase in frequency of extreme weather events such as extreme rainfall, frequent cyclones and heat waves.

“Deaths resulting from toxic pollution are highest where the distribution of toxic pollution is greatest and, critically, also where the impacts of climate change pose the greatest risk,” the study, titled Global Distribution and Coincidence of Pollution, Climate Impacts, and Health Risk in the Anthropocene, said, in a specific reference to India and China.

Scientists at University of Notre Dame found a “strong and statistically significant” link between the two hazards and said the countries which are at most risk from climate change are also the countries with highest risk from toxic pollution.

A vital difference between climate change and air pollution is that greenhouse gases that cause global warming are considered non-toxic whereas air pollutants such as particular matter or nitrogen dioxide are toxic.

To make the study useful for policymakers, the authors ranked 177 countries on “Target”, a measure that combined a country’s climate impact risk, toxic pollution risk and its potential readiness to mitigate these risks. China is the world’s leading total GHG emitter and India is on track to join it at the top and they are the two top ranked countries in terms of toxic air pollution.

Based on these criteria, the study ranked Singapore, Rwanda, China, India, Solomon Islands, Bhutan, Botswana, Georgia, the Republic of Korea and Thailand as top 10 countries. “The top one-third of countries at risk of toxic pollution and climate impacts represent more than two-thirds of the world’s population, highlighting the magnitude of the problem and unequal distribution of environmental risk,” researchers wrote in the paper published in peer-reviewed scientific journal PLOS One.

Among those countries appearing at the bottom of the list are Equatorial Guinea, Iraq, Jordan, Central African Republic and Venezuela. “These (bottom of the table) nations are most likely to have outstanding governance issues that currently stand in the way of effectively addressing pollution and climate change,” the study said.

On India and China, the two largest countries, together representing over 2.5 billion people, the study said they have relatively high Proportion Mortality ranks – India ranked 5th and China 13th with 23.5% and 17.9% of annual deaths associated with toxic pollution, equalling 2.3 and 1.9 million premature deaths annually, respectively.

The study combines assessments of the risks of toxic emissions (e.g., fine particulate matter), nontoxic emissions (e.g., greenhouse gases) and people’s vulnerability to them. Researchers found a strong and statistically significant relationship between the spatial distribution of global climate risk and toxic pollution. In other words, countries that are most at risk of the impacts of climate change are most often also the countries facing the highest risks of toxic pollution.

“The top one-third of countries at risk of toxic pollution and climate impacts represent more than two-thirds of the world’s population, highlighting the magnitude of the problem and unequal distribution of environmental risk,” says the paper.

“It is not surprising to find that these risks are highly correlated, but this study provides the data and analysis to inform policy, data and analysis that were previously lacking,” Debra Javeline, an associate professor of political science at the university said in a statement.

As the abstract points out, previous research demonstrates that low-income countries face higher risks than high-income countries from toxic pollution and climate change. However, the relationship between these two risks is little explored or tested, and efforts to address the risks are often independent and uncoordinated. This study provides analysis for 176 countries and found a strong and significant relationship between the distribution of climate risk and toxic pollution. It also found that inequities in pollution production, economic status, and institutional readiness are interconnected and exacerbate risk for countries already in the highest risk categories for both toxic and non-toxic (greenhouse gas) pollution.

The findings have policy implications, including the use of the proposed Target assessment to decide where best to address toxic and non-toxic pollution simultaneously, based on the need to minimize human suffering and maximize return on effort.