Global Air Quality, past present and future: an introduction

Global Air Quality in 2019 was responsible for 7 million premature deaths, extensive crop loss and declines in biodiversity across Europe, North America and East Asia. Air pollutants also contribute directly to climate change through changes in the energy balance of the planet by some of the gaseous pollutants, notably ozone and also by particulate matter. There are therefore strong motives to understand the science, develop policies to mitigate effects and identify technical solutions to reduce emissions substantially. The objectives of the Royal Society Air Quality Discussion Meeting in November 2019 were to describe the way air pollution developed, articulate the main characteristics of the current global air quality issues and assess the likely changes in the scale and distribution of air pollution through the twenty-first century. The policy responses to date have generally been slow to develop, in part because the effects were not anticipated and, to some extent when observed, were regarded as an acceptable burden for the benefits of new technologies. Many of the large-scale air pollution problems were discovered by scientists engaged in unrelated monitoring or research activities. Thus, the effects became widespread and severe before the scale of the problems were appreciated, as in the case of Acid Rain. The polluting industries and governments sometimes engaged, at least initially, in obfuscation activities in an attempt to minimize the importance of the problem. The slow policy response has been a feature of air pollution globally. The meeting brought together a broad range of researchers and practitioners working in fields related to air pollution and its effects on human and environmental