Filtering Out The Good From The Bad - November 2017

With diesel pollution stories constantly in the news, it has raised questions as to whether ventilation companies are actually doing anything to address this concern. However, new products are now emerging all the time and, even though some are not proven in the market, it indicates the issue is slowly being recognised - and a resolution may not be too far away. Tyson Anderson, Sales & Marketing Director at Titon explains, only models adhering to the necessary health standards and Building Regulations should be considered.

In order to ease people’s minds about air pollution, manufacturers and specifiers need to investigate how to successfully combat it, as people’s health and lives should not be compromised. There is evidence that high levels of NO2 can inflame the airways in the lungs and, over a long period of time, affect their functionality. People with asthma are particularly affected, while NO2 can also cause other respiratory problems, immunity to infections such as bronchitis plus, in some cases, heart disease. As a result, it is becoming imperative to design cost effective ventilation systems to cope with the increased potential for air pollution. Consequently, MVHR manufacturers are continually looking to develop products to help combat such pollutants and improve air quality inside the home.

The issue has now come to a head, with DEFRA estimating NO2 pollution causes up to 23,500 premature deaths a year (UK), with traffic pollution contributing to the rising number of children with asthma. Their data reveals almost 3,000 schools and many planned homes are in areas breaching WHO (World Health Organisation) air pollution limits this includes levels of NO2 above the stringent levels set out in the EU Directive 2008/50/EC – European Union Air Quality and Clean Air for Europe 2008. Such has been the concern that parents are now being fined for not switching off their engines when picking up children from school (Road Traffic (Vehicle Emissions) Regulations 2002)* and fines rising to £80 in areas such as Westminster are being issued; but is this enough, or does more need to be done?

Trimbox NO2 Filter

It has already been highly publicised that indoor air quality can be significantly improved via effective ventilation. Indeed, by specifying MVHR System 4, moisture and airborne contaminants will be removed, resulting in a healthier indoor environment for occupants. In addition, there are also now specially designed NO2 filters which can be added to an MVHR system and remove pollutants being produced by diesel engines. These pollutants include sulphur dioxide, hydrogen sulphide, hydrogen chloride and chlorine. NO2 filters also help combat ammonia odours, while absorbing VOCs and solvents.

From a legislative perspective, it is important any NO2 filters installed conform to the EU Directive 2008/50/EC (AKA the Clean Air for Europe programme or the CAFE Directive). This programme was launched with the aim of developing a long-term, strategic and integrated policy to protect against significant negative effects of air pollution on human health and the environment.

Filter units also need to comply with Part F (ventilation) of the Building Regulations – especially the pages relating to ADF’s performance criteria for dwellings (also applicable to offices) stating that exposure to nitrogen dioxide (NO2) should not exceed 288 μg/m over a one-hour average, and 40 μg/m over a long-term average. However, interestingly, ADF doesn’t stipulate that filters are a necessity; perhaps this needs to be reconsidered, following all the recent findings concerning air pollution?

NO2 filters – such as Titon’s own, award-winning Trimbox – incorporate balanced flow technology to reduce NO2 to an acceptable mean concentration level of 40µg/m3 while improving indoor air quality. (Indeed, independent tests have demonstrated such units to absorb 95% of NO2 not only in normal, continuous ventilation mode but also at boost or higher ventilation rates.)** These units can be installed in both intake and supply ducting. Additionally, they can be used in small to large dwellings, provided they are able to operate with variable airflow.

However, we are now seeing an increased amount of manufacturers offering many different NO2 filters, but these are not necessarily as effective as other models on the market. Some products are incorporating large carbon filters to adhere to dwell time which increases airflow to achieve absorption rate, for example; however, these can only go on to large and cumbersome units – which results in it being costly and awkward for installation.

A healthy ventilation strategy with adequate filtration is crucial. After all, buildings are essentially acting similarly to a lung - drawing in polluted air from outside air before breathing out processed and filtered indoor air. While we have known for many years the benefits of a successful MVHR strategy, we now need to extol the virtues of adding high quality NO2 filters to these systems to ensure occupants remain fit and healthy for the foreseeable future.


* Source:

** Source: All performance data for the new filters has been derived by independent testing at a UKAS recognised test house. The testing regime was carried out to the World Health Organisation’s and European Union standards. The test report concludes that: “Both filter units performed very well, with nitrogen dioxide filtration performances of approximately 95% being achieved”.