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  • Writer's pictureMark Bowden

Emissions, LEZs and CAZs...what does it all mean?

Almost all economic and societal activities result in emissions of air pollutants, the effects of which result in real losses for the British economy, the productivity of its workforce, and the health of its natural systems. The UK’s air quality has improved considerably in the last 60 years but has not yet attained the air quality foreseen in legislation or recommended by the World Health Organization. The effects of poor air quality on public health have been felt most strongly in urban areas, with levels of particulate matter (PM) of particular concern; and in ecosystems leading to biodiversity loss.

Low Emission Zones

A Low Emission Zone (LEZ), or Clean Air Zone (CAZ) aims to reduce pollution levels and improve air quality. They're often found in areas with high levels of air pollution - usually towns or city centres.

In most cases, you pay to go through these zones if your vehicle has high emissions. If you don’t pay the fee, you may have to pay a Penalty Charge Notice (PCN). Most fees apply to diesels built before September 2015 as usually, these vehicles don't meet emission standards. In some cases, fees don't apply to petrol cars built after January 2006. Electric, certain hybrids and other vehicles with zero emissions won't have to pay to enter these areas. Dispensation is also available for older cars, typically with Euro 5 engines which are converted to Euro 6 Standards.

The decision on whether you are charged or not is determined by an Automatic Number Plate Recognition (ANPR) system which will be installed in the city or town where the LEZ/CAZ is in place. This will record your number plate when you drive in or out of the zone and then check your details against those stored by the Energy Savings Trust. The DVLA are not involved with this programme and the EST are responsible for ensuring accreditation with the Clean Vehicle Retrofit Accreditation Scheme. Any conversion which does not reach this standard will not prevent charging within the zones.


A new zone will be achieved this year by expanding the existing Ultra Low Emission Zone (ULEZ), introduced in April 2019, from its current position in central London to the North Circular Road (A406) and South Circular Road (A205), excluding the circular roads themselves.

Next time we will look at emissions, particulate matter and NOx...

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