Dirty air will doom us to early death

The new analysis of global burden of disease (GBD) estimates released by the US-based Health Effect Institute (HEI) has exposed stunning results. Globally, air pollution is estimated to cause more than 4.2 million early deaths—of these, 1.1 million deaths occur in India alone. It is more than a quarter of the global deaths. India ranks second in PM2.5-related deaths in the world and nearly equal China, which scores the highest number of early deaths due to PM2.5.

Worse, India now tops the dubious list of highest number of premature deaths due to ozone pollution. The rate of increase in early deaths in India is quite scary. While early deaths related to PM2.5 in China have increased by 17.22 per cent since 1990, in India these have increased by 48 per cent. Similarly, while early deaths due to ozone in China have stabilised since 1990, in India these have jumped by 148 per cent. This demands urgent intervention. With the release of State of Global Air 2017 by the HEI, the GBD estimates have now become annual. "We see increasing air pollution problems worldwide, and the new report explains why air pollution is a major contributor to early death. We have seen progress in some parts of the world—but serious challenges remain," said Dan Greenbaum, President HEI, the global research institute that designed and implemented the study.

Air pollution is the leading environmental cause of death worldwide. Approximately 92 per cent of the world's population lives in areas with unhealthy air. This new report—State of Global Air 2017 by HEI—is a deeper analysis of the earlier GBD estimates of 2015 and looks at the long-term trends from 1990 through 2015.

The HEI has built on the GBD project of the Institute for Health Metrics and Evaluation (IHME), involving more than 2,000 researchers who enumerate and track death and disability and the influence of behavioral, dietary and environmental risk factors for more than 300 diseases and injuries, by age and sex, from 1990 to the present, in 195 different countries and territories. "The new report is a deeper analysis extracted from the most recent GBD, (2015, published last year). It allows one to look at long-term trends from 1990 through 2015," explains Robert O Keefe, vice-president, HEI.

India cannot afford to remain complacent or in denial anymore. With so many people dying early and falling ill and losing productive years due to particulate and ozone pollution, it is a state of health emergency. This demands nation-wide intervention to ensure stringent mitigation and a roadmap to meet clean air standards. Very recently, India's Environment Minister was in denial claiming there is no conclusive data to establish direct correlation of death exclusively due to air pollution. The new GBD data calls for even more urgent and decisive interventions.

India ranks second in early deaths due to PM2.5. Deeper country-wide analysis shows that India is at the highest risk. The number of premature deaths attributable to PM2.5 in India is second highest in the world. It has nearly equalled China's dubious record. While China has recorded 1,108,100 premature deaths in 2015, India recorded 1,090,400 deaths. Even though India had started off with a much lower number of people dying early deaths in 1990, it has quickly caught up with China.

Not only the absolute numbers of early deaths are high in India, but the rate of increase is also much higher than China. While early deaths related to PM2.5 in China have grown by 17.22 per cent since 1990, in India, it has increased by 48 per cent.

While in China the average rate of increase in early deaths due to PM2.5 since 1990 has been 3.33 per cent, in India it is as high as 8.18 per cent.

Premature deaths in India are also highest among the South Asian countries – it is nine times greater than the neighbouring Bangladesh and eight times higher than Pakistan. This is a profoundly serious issue as we know from the past GBD estimates air pollution is already the fifth largest killer in India.

Without anyone noticing it, ozone, a very reactive gas, has become a serious health problem in India. Even though the absolute number of early deaths due to ozone is far less than those caused by PM2.5— 107,800 due to ozone as opposed to 1,090,400 due to PM2.5—India records the highest number of cases in the world. Ozone aggravates respiratory problems, especially chronic obstructive pulmonary disease (COPD). In fact, very recently, India has included COPD in its non-communicable disease programme. This only brings out the importance of reducing environmental risk factor.

Ozone is responsible for the much higher rate of increase in early deaths than particulate matter. It is the rate of increase in India that is scary. Ozone-related early deaths in India have recorded the highest increase—by as much as 148 per cent since 1990. During the same period, the health risk from particulate pollution, which is already a tremendous problem, has increased by 48 per cent.

Ozone-related early deaths in India are 33 per cent greater than those recorded for China. India has also recorded much faster increase in ozone-related deaths since 1990 than China—an average 20 per cent increase in India as opposed to 0.50 per cent in China. In 1990, ozone deaths in India were far less than China. But now India has surpassed China, where ozone-related deaths have remained more or less stable.

In the South Asian region, the ozone deaths in India are 13 times higher than Bangladesh and 21 times higher than Pakistan.

As ozone monitoring in India is extremely limited, and there is barely any country-wide data, we followed up to understand the reason for high number deaths related to ozone. The HEI scientists have explained that ozone in GBD estimates is from chemical transport model, but the evidence of increasing ozone levels in India, especially in north India, is seen from the available measurements. Not many routine measurements are available except those that are from aircraft campaigns.

Increasing ozone burden in India concerning deaths is due in part to population growth and ageing. Michael Brauer, associated with the new study, says, "For ozone, the increase in exposure is so large that it overwhelms the improvements in underlying chronic obstructive pulmonary disease mortality. In other words, exposure matters and combines with ageing and population growth to lead to increasing deaths. For particulate matter, there is an increase in exposure, but the overall improvement in mortality rates are large enough to lead to a decrease in attributable mortality rates."

Ozone is not directly emitted but is formed from the reaction of a variety of gases like the nitrogen oxide, carbon monoxide, and volatile organic compounds under the influence of sunlight and temperature. To some extent, rising temperature is also aggravating this trend. In fact, a new genre of science is showing that countries such as India that are close to the equator, the climatic projections suggest further increase in ozone. Some more recent studies show these pollutants in tropical regions cause more ozone per tonne of emissions than emissions from regions further north like Europe and North America. Not only the emissions of gases are increasing but also the geographical disadvantage is adding to India's plight. Already, the connection between urban heat island and ozone has drawn attention in Indian cities.

India will have to watch this science well. If the problem is going to grow in tropics and sub-tropics and around the equator, it is also important for the global community to understand the regional drifts of ozone precursor towards equatorial regions as well.

India will be well advised to take early and stringent steps to control ozone precursors which are tough to control, as seen from the developed world. It would mean very stringent control of gaseous emissions from combustion sources, including vehicles. Air pollution problem cannot be dismissed as dust. Ozone precursors like nitrogen oxides, carbon monoxides, and volatile organic compounds also have severe local public health impacts. "In short, ozone is likely to become more important in India, and as we know from US story it is harder to manage and control", warns Robert O Keef of HEI.