NOx is the general term for a group of chemicals, the most prevalent of which are Nitric Oxide (NO) and Nitrogen Dioxide (NO2). While NOx gases occur naturally, they are also created by human activities.

Vehicle emissions are one of the primary sources of man-made NOx, they are created when nitrogen and oxygen react together when fuel burns. NOx emissions create smog and acid rain. NOx also contributes to ground level Ozone, adding to the greenhouse effect and a host of other environmental problems.

Air Pollution or Climate Change?
Air pollution and climate change are distinct phenomena with their own impacts, but can exacerbate each other and have real human and economic costs.

Air Pollution
NOx reacts with other chemicals in the air to form particles which can cause adverse impacts on cardiovascular health and lung function.

Studies have also shown a correlation between NOx and inhibited foetal development which can have a permeant influence on growth and health throughout life, including possible impacts on intelligence and neurological development. Beyond childhood, long term NOx exposure has further health implications for adults contributing to the development of asthma and cancer.

Climate Change
In the same way that NOx reacts with other chemicals in the air to form particulate matter, it can also form ground level Ozone (O3).

When found at ground level O3 has a significant radiative effect, second only to carbon dioxide and methane, and contributes to global warming.

O3 is associated with acute health conditions and has been shown to cause lung inflammation and tissue damage. It impacts lung permeability, which makes people more susceptible to infectious diseases. In addition, like NOx particulates, studies have shown that O3 contributes to the development of asthma, and particularly in people who are regularly exercising in arears of high concentrations.

Environment and Vegetation
O3 can physically damage leaf structure, and cause reductions in growth and yield of some plant species. While this has obvious climate implications, it has real economic consequences. One study from 2005 suggests that in Sweden losses caused by a reduced timber yield costs EUR56 million annually. O3 also has detrimental impacts on carbon absorption by the natural environment (i.e. ‘carbon sinks’) leading to increased build up of carbon dioxide, a dangerous greenhouse gas.

Food production
O3 can reduce the nutritional quality of crops including wheat, rice and soya bean. One study of the effects of O3 on crops in the USA indicated that it costs between $2-4billion annually. Such effects are likely to have their greatest impacts in developing economies where emissions and O3 are predicted to increase over the following decades. Combined with other climate change impacts, this may contribute to widespread food and political instability.

Are NOx emissions a local problem?
Yes. NOx particulate matter disperses relatively quickly, confining the worst direct effects of NOx particulates to areas of dense population and heavy traffic. However, NOx reactions which contribute to O3 take place over several days allowing O3 to travel. Some weather conditions can move O3 hundreds of miles, across whole continents, making this a real local and global problem.

What can I do to help?
The technology to regulate vehicle NOx emissions already exists. Therefore it is within the power of car manufacturers to reduce the significant impact of road transport on NOx emissions. To date they have chosen not to.

Only through collective action can we force a change. Join the claim now.