“Plastic waste is a growing global environmental concern. While we see more research on the impact plastic pollution is having on the natural environment, there has been less work trying to understand the human behavior that drives plastic pollution,” says study coauthor and associate professor Alberto Salvo of NUS Economics.

“This is where our study seeks to contribute—finding a strong causal link between air pollution and plastic waste through the demand for food delivery. Air quality in the urban developing world is routinely poor and in the past decade, the food delivery industry has been growing sharply. The evidence we collected shows a lot of single-use plastic in delivered meals, from containers to carrier bags.”

The results of the study appear in Nature Human Behaviour.

The researchers focused their study on China, which is among the world’s largest users of online food delivery platforms, with 350 million registered users. An estimated 65 million meal containers end up in the trash each day across China, half of them from office workers.

The study surveyed the lunch choices of 251 office workers repeatedly over time (each worker for 11 workdays) in three often-smoggy Chinese cities—Beijing, Shenyang, and Shijiazhuang—between January and June 2018. To complement the office-worker survey, the researchers also used the 2016 Beijing order book of an online food delivery platform, which broadly represented all market segments that the food delivery industry serves. This let them collect observational data on 3.5 million food delivery orders from about 350,000 users.

They then compared data from the survey and order book with PM2.5 measurements (fine particles less than 2.5 micrometers in diameter) during lunchtime periods from the air-monitoring network in all three cities. It was observed that PM2.5 levels during these periods were often well above the 24-hour US National Ambient Air Quality Standard of 35 μg/m³, making pollution highly visible. The researchers were careful to control for confounding factors such as economic activity.

Both data sources indicated a strong link between PM2.5 (haze) pollution and food delivery consumption. Correcting for weather and seasonal influences, the firm’s order book revealed that a 100 μg/m³ increase in PM2.5 raised food delivery consumption by 7.2%. The impact of a 100 μg/m³ PM2.5 shift on office workers’ propensity to order delivery was six times larger, at 43%.

Read the full article about smog and plastic waste from the National University of Singapore at Futurity.