This year, World Environment Day is focused on air pollution. Almost all of us are affected by it: 92 per cent of people worldwide do not breathe clean air.

So in 2019, those celebrating World Environment Day will urge governments, industry, communities, and individuals to come together to explore renewable energy and green technologies, and improve air quality in cities across the world.

Over the years, some World Heritage cities have even listed air pollution as a threat, often due to traffic. Polluted air is not only a health issue, but also has corrosive effects on marble and other valuable building materials. The City of Valletta (Malta), Historic Cairo (Egypt), the Colonial City of Santo Domingo (Dominican Republic), the Historic Centre of Bukhara (Uzbekistan), the Historic Centre of Rome (Italy) and the Imperial Places of the Ming and Qing Dynasties in Beijing and Shenyang (China) have all reported the negative effects of pollution on the constructions that make their cities unique, threatening their outstanding universal value.

Air pollution costs the global economy $5 trillion every year in welfare costs. Our best efforts to reduce pollution would benefit all of us, not just the cities that we live in.

To read more about World Heritage Cities and innovative ways to manage them, see the latest issue of the World Heritage Review.