Taxation of Company Cars in Belgium - European Commission
https://ec.europa.eu/info/sites/info/files/eb026_en.pdf

Air pollution more harmful to children in cars than outside, warns top scientist
https://www.theguardian.com/environment/2017/jun/12/children-risk-air-pollution-cars-former-uk-chief-scientist-warns

“It is nine to 12 times higher inside the car than outside,” he said. “Children are in the back of the car and often the car has the fans on, just sucking the fresh exhaust coming out of the car or lorry in front of them straight into the back of the car.”