Can your denim jeans help combat air pollution?

In Option E : Environmental chemistry under sub-topic E1 students are asked to both describe the main sources of oxides of nitrogen in the air and to evaluate current methods for their reduction. The main source is from the combination of nitrogen and oxygen that occurs during the high temperatures reached inside the internal combustion engine. The traditional social answers to reducing this form of air pollution include  car-sharing or using alternative forms of transport to minimise the overall use of automobiles. The chemical methods involve altering the fuel/air mixture entering the combustion chamber or using a catalytic converter to reduce the exhaust oxides of nitrogen to elemental nitrogen.

Professor Tony Ryan from the University of  Sheffield in the UK has recently come up with an innovative alternative way of reducing this pollution.  It is all to do with the way you wash your clothes! Putting an additive called ‘CatClo’ into your weekly wash will cause the clothes to act as a catalyst which will absorb oxides of nitrogen. The surface catalyst is a microscopic form of titanium oxide which he claims is completely harmless. When the titanium oxide nanoparticles come into contact with the nitrogen oxide molecules in the presence of daylight they “oxidize them” in the fabric. It is claimed that “the product is completely odourless and pose no pollution hazard as it can be removed harmlessly when the clothes are next washed”. It is estimated that one person would be able to remove about 5g of nitrogen oxides from the air per day using their clothing. This should help to reduce asthma and other respiratory diseases.  Tony Ryan has teamed up with Professor Helen Storey from the London College of Fashion to commercialise the product and promote greater awareness of its potential. Denim jeans are a particularly suitable material to carry the catalyst and as Ryan says there are more pairs of jeans than there are people on this planet. They have produced a video promoting CatClo  and further information can be found on their website.
 

Despite all the hype and the literature I failed to find the answers to two questions that I would like to ask. The first one is: What exactly is the “oxidized product”? Under frequently asked questions the literature does state:

“When the light shines on the photocatalyst, the electrons in the material are rearranged and they become more reactive. These electrons are then able to react with the water in the air and break it apart into 2 radicals. A radical is an extremely reactive molecule. These radicals then react with the pollutants and cause them to break down into non-harmful chemicals.”

However there seems to be no ‘hard’ chemistry provided as to the exact identity of these “non-harmful chemicals”.

I presume the non-harmful chemicals are some form of nitrate? If this is the case the nitrates would easily be removed when the clothes are next washed, but where to? – the answer, of course, is into the waste water. The literature states that the titanium oxide will not pose a water pollution problem but what about the “oxidized nitrogen oxides” product? The presence of nitrates in fresh water is an increasing problem. Nitrates are difficult to remove during waste water treatment (see the tertiary treatment of waste water in assessment statement E.6.2 ). My second question is therefore: Does CatClo simply transform an air pollution problem into a water pollution problem?