The way forward

In this chapter we summarise the important steps necessary to improve air quality and reduce global warming. It is essential to have legislation on indoor air quality, particularly on PM_2.5 and carcinogenic VOCs which should be set at WHO outdoor air quality standards. Urban and regional air quality will greatly benefit from the replacement of gasoline and diesel passenger cars by electric vehicles and heavy-duty vehicles should give way to hydrogen technology. While the elimination of coal- and gas-fired power stations will improve air quality, atmospheric CO₂ levels will take a long time to respond and it will take many decades for global climate change to show a real benefit. Reduction in methane from all sources will be a win–win policy, especially when combined with ozone reduction. However, it is when we have a scenario of reforestation combined with reductions in emissions of all greenhouse gases that we can realise an improvement in climate change that will enable the planet to limit global warming to 1.9°C. Over the next 30 years, air quality will dramatically improve and we will succeed in reversing global warming and bring it down to 1.5°C by 2055.