We used machine learning to identify the biggest plastic pollution hotspots in more than 50,000 towns and villages around the world. Our new global model shows the most detailed picture of plastic pollution ever in the environment, with India having the highest concentrations – primarily because most of the waste goes uncollected.

Plastic has been found everywhere, from the deepest ocean trenches to the highest mountain peaks, but these observations provide only isolated snapshots of the bigger picture of plastic pollution. The bigger challenge is figuring out where and how this plastic is entering the environment so that pollution can be prevented at source.

This is not an easy task. The most difficult aspects to measure are the “emissions” emitted or released from material systems and activities; that is, macroplastics (anything larger than 5mm in size). This includes litter that flies out of bins or falls out of trucks, as well as litter that people accidentally or deliberately drop.

We have seen that garbage is the largest source of emissions in the developed world, where waste management systems are tightly controlled. Conversely, in developing countries, uncollected waste is the dominant source.

Our new computer model using artificial intelligence shows how plastic moves from a regulated system into the environment, where it becomes very difficult to capture and control. We needed to determine how plastic leaves the regulated system, and we found that of the 52 million tonnes of waste entering the environment each year – equivalent to the weight of 8.7 million African grey elephants – the largest source is uncollected waste. That’s around 68% of the weight of all pollution, or 36 million tonnes each year.

Therefore, it is wrong to believe that plastic pollution is caused by irresponsible human behavior. The main reason for this is that 1.2 billion people do not collect any solid waste. Instead, they must burn it, bury it, or scatter it on land or water.

Open burning of waste is very efficient and accounts for 57% of all plastic pollution worldwide by weight. This involves burning waste on open fires without any controls to prevent hazardous emissions from entering the environment and harming our health. This practice is popular perhaps because it ensures that waste is disposed of, reduces the burden on waste management authorities and reduces the unsightly appearance of waste dumped on the ground.

India has become the biggest plastic polluter, dumping 9.3 million tonnes of plastic into the environment each year, a fifth of the total – 2.7 times more than the two biggest polluters, Nigeria and Indonesia.

India ranks first because only 81% of its waste is collected. But it also creates much more waste than some previous models suggested. Official government sources estimate 0.12 kg per person per day, but these estimates exclude many rural areas, so the real number is closer to 0.54 kg per person per day. The combination of so much waste, a large population, and low collection rates creates conditions for increasing plastic pollution.

Purposeful action

Identifying hotspots of this pollution helps policymakers design more targeted ways to combat plastic pollution. Countries with more plastic pollution tend to have fewer resources in terms of money and infrastructure, so they tend to be the least equipped to limit their emissions.

A better understanding of how waste is disposed of around the world will allow governments to direct their limited resources to areas where plastic pollution is most severe. Our model will also help them develop action plans that can realistically meet the targets agreed upon in the Global Plastic Pact, the international agreement currently under negotiation to reduce plastic pollution worldwide.

Reducing plastic consumption is one solution to limit plastic pollution. But plastic does not exist in isolation. It is part of a complex mix of materials in waste, and we must consider them all together. For example, food waste, together with other biodegradable materials, is responsible for most of the climate emissions from the waste management system when stored in landfills.

If we reduce our use of plastic, we will need to find ways to reuse or replace materials. However, previous studies have shown that the ability to do this is limited and that in practice we will be producing plastic for a long time in the future. We need to tackle plastic waste more effectively now. Finding ways to expand waste collection services could significantly reduce plastic pollution and benefit billions of people.