Industry Background

Environmental air pollution is a globally recognised public health crisis that potentially affects every living thing on the planet yet is still largely unrecognised or ignored.

The British government’s advisory committee on the Medical Effects of Air Pollution states that the average reduction in life expectancy of a British citizen caused by unavoidable exposure to air pollution “is larger than that of several other established mortality risks” including road traffic accidents and passive smoking (COMEAP 2010).

Human activities are at the root of most air quality problems. Geophysical activities such as volcanic eruptions and sandstorms are exceptions.

Key outdoor pollutants include nitrogen and sulphur oxides, ozone and VOCs/particulates from industrial/combustion processes and seasonal organics such as pollen.

Despite recent industry initiatives aimed at increasing public awareness, air pollution in the UK remains is a largely unseen and ignored phenomenon that is damaging the health of the nation and causing tens of thousands deaths every year.

Similarly, indoor air pollution is a growing public health emergency that has been described as the sleeping giant of the future. Most people spend 80-90% of their time indoors so are exposed to indoor air to a far greater extent than outdoor air. There is growing evidence of the linkage between poor indoor air quality and increases in poor mental and physical health, poor productivity at work, short/long term illnesses and premature deaths.

Indoor air pollution has been an increasing problem ever since the early 1970s when we started to build more energy efficient homes. In those days the objective was to save money due to the cost of energy but more recently the objective has changed to combating global warming by reducing carbon emissions. Indeed since 2005 the British government is committed to reducing UK carbon emissions by 80% by 2050. This target was recently increased to net zero or 100%.

Energy efficiency has the effect of sealing up a property which means there is a risk that moisture and pollutants can build up, especially if ventilation is ineffective. This is particular problem in the UK where our world renowned weather always produces cold winters and people keep windows closed.

Problems with indoor air quality include those linked to moisture retention such as condensation, mould & mildew, musty odours and dust mites/allergies. They also include problems linked to the build up of pollutant gases and particulates such as NOX, radon, ozone, traffic soot and pollen from outdoors and CO2, CO, VOCs and cooking/tobacco particulates from indoors ranging from headaches, skin irritations and fatigue affecting productivity to serious respiratory and mental illnesses, cancer and premature death. Children and the elderly are particularly prone to indoor air quality related illnesses.

Air pollution has long been a concern in the UK with coal burning records dating back to 1257.

The Industrial Revolution saw great increase and smog/pea souper pollution which was very common way into the 20th century.

Great Smog Dec 1952 caused thousands of deaths from inhalation of smoke and toxic gases mainly from domestic fires caused by temperature inversion weather event which held these gases at ground level. The Clean Air Act of 1956 followed.

In the last decades of 20th century acid rain became an issue as sulphur laded fumes were transferred from domestic coal burning to tall stacks of power stations.

In the UK factories and fireplaces no longer fill the air with the thick smoke of the 1950s. The main source of outdoor air pollution in the UK is now combustion products from road vehicles which used to include lead but today is predominantly NO2 and particulates. Diesel produces more NO2 than petrol and more fine/ultra fine particulates. Exposure to diesel fumes causes lung/bladder cancer. The recent VW Dieselgate episode cast the spotlight on air quality issues caused by diesel engines. According to research from MIT (Yim & Barrett 2012) 39% of lost life expectancy to pollution from combustion sources in the UK is from transport (mainly road) emissions, 13% to power generation, 4% to industry and 32% from transboundary pollution from Europe with the rest from other sources including residential and agricultural activities.

The most widespread outdoor pollutants in modern Britain include particulates (PM 2.5/10), NO2 and ozone. Other pollutants of concern are SO2, CO, polycyclic aromatic hydrocarbons, arsenic, cadmium, nickel, benzene, and lead.


Today, the highest levels of particulate pollution occur mainly in the vicinity of busy roads in urban areas but also close to heavy industry. A significant percentage of particulate matter is secondary meaning it is produced in the atmosphere from chemical reactions of pollutant gases (agriculture is a major cause of this).

Short and long term exposure to particulates (PM10 and PM2.5) causes serious health effects such as COPD, emphysema, bronchitis, cardiovascular disease, stroke and heart attack. Key symptoms of exposure include asthma, wheezing and reduced lung function. It also affects lung development in children. Chronic exposure to PM2.5 is thought to cause 6-13% increase in long term risk of death from cardiopulmonary diseases.


Direct health effects are bad. Also NO2 reacts in the atmosphere to create 2 more harmful pollutants – ozone and ammonium nitrate. In recent years roadside monitoring of NO2 levels has shown frequent breaches of limit values along thousands of miles of British roads (DEFRA).

Short term effects: inflame/restrict airways causing breathing difficulties especially for asthmatics. Long term effects: reduction in lung function in children.

Health experts believe NO2 exposure in the UK is a major contributor to excess mortality.


Ozone is not emitted by vehicles or any other source but is produced in sunny skies that have been polluted by other gases. Levels can increase during photochemical smog events which requires NO2 and sunny weather.

Inhalation of excess ozone over a few hours can cause serious respiratory problems. Long term exposure can cause permanent scarring of the lungs.

Most parts of the UK (rural areas too) experience unsafe levels of ozone.


The decline of SO2 levels over last 50 years proves air pollution can be reduced if there is a will.

Excess SO2 inhalation symptoms include COPD, asthma aggravation, decreased lung function especially in children. SO2 is also a PM2.5 precursor.

CO, Benzene, Lead

CO is produced from vehicle emissions. Benzene is a carcinogenic VOC and causes leukaemia. Lead is extremely toxic.

Air Pollution & the Weather

Wind and rain help eliminate/remove gaseous and particulate pollution from the air through dilution and dispersal/removal.

High pressure and good weather can create significant problems with air pollution. Summer photochemical smogs are caused by temperature inversions where warm air moves above cooler air at ground level and causes pollutants (NO2, ozone, PM) to accumulate. Such phenomena are common in cities such as Los Angeles, Milan and sometimes UK.

Scale of the Air Pollution problem

On a global scale, WHO (2014) estimates 3.7 million deaths each year can be attributed to ambient air pollution. OECD estimates this will rise to 6-9 million deaths per year by 2060.

DEFRA estimates NO2 pollution is responsible for 23,500 deaths in the UK each year. Royal College of Physicians estimates PM & NO2 exposure responsible for 40,000 deaths in the UK each year.

Everybody in the UK is at risk to involuntary exposure

In recent years and per it obligations under EU law, the UK developed it’s own air quality monitoring network – the Automatic Urban and Rural Network (AURN) which consists of monitoring stations located throughout the country working on a 24/7 basis. The measurements from each station are sent to publicly accessible database which then validates against limits/thresholds contained in the UK’s Air Quality Standards (AQS) legislation which is based on WHO-AQG (Air Quality Guidelines).

The main pollutants regularly breach the AQS year after year. By 2016, of the 389 local councils in the UK, 248 had declared “air quality management areas” (AQMAs) and there were 579 individual AQMAs with NO2 breaches at that time.

DEFRA reports annually the main pollution episodes for the previous year in its “Air Pollution in the UK” reports which are available on its website.

Challenges of managing Air Pollution in the UK

Questions that could be asked of the effectiveness of the AQMS strategy include:

  • Has the UK government undertaken minimum requirements and is this enough ?
  • The precise locations of monitoring equipment could be giving a false picture i.e.. too far away from busy roads, too high up above the ground, not enough monitoring stations (although hyperlocal data sources are becoming more commonplace – some academic, some commercial ie. Kings College London Air Quality Network, Breezometer etc)
  • EU objectives allow a number of exceedances per year meaning WHO guidelines can be breached on a regular basis (once every 10 days) yet EU objectives are still being met. This gives a misleading picture of UK air quality and may be causing members of public to think there is no issue.
  • In 2014, 84% of PM10 AQS had one or more exceedances during the year yet 0% failed the objective. NO2 problem more widespread. Also, figures for UK objectives are based on sites within AURN only whereas separate monitoring show more locations would also be in breach.


Meeting AQS by no means guarantees the safety of public health.

UK AQS for PM10 is higher than WHO guideline (20 microgram/m3) meaning our measured PM10 can be higher than the WHO guideline and yet we can be shown to be meeting objective. WHO has set interim targets for PM10 for those who have not committed to the recommended WHO level (20 microgram/m3). WHO estimates UK AQS level (currently 40 micrograms/m3) carried additional mortality risks of between 3-9%). In summary, UK citizens are currently being exposed to these increased risks yet are being told air quality standards are being met.

For PM2.5, concentrations of 25 microgram/m3 carry additional mortality risk of 9%. UK AQS only recently added daily PM2.5 exposure.

There is an EU requirement for public to be informed if higher “alert” thresholds are exceeded but these are not widely publicised and ideas such as air quality forecasts  remain just ideas at present. In 2014, the Saharan dust incident received TV/media coverage only because the pollution was visible as dust on car bonnets which was unusual and therefore of interest (rather like potholes). Broader solutions regarding public awareness and publicising air quality forecasts and threshold breaches can only come from central government policy.

In the UK, air pollution in London alone costs £3.7bn per year.

DEFRA current projections relating to 2008 EU Air Quality Directives are that compliance will not be achieved until 2020 (in 10 zones), 2025 (in 23 zones), 2030 (in 2 zones) and after 2030 in 3 zones which includes Greater London. Extensions due to failure to comply with NO2 emissions have been made for 38 of the 43 air quality zones.

In 2015, global leaders agreed in Paris to shift away from fossil fuels by mid century but there is skepticism about the level of commitment to decarbonisation by the UK government (despite recent announcements). Evidence supports this view – reduction of subsidies for solar panels, withdrawal of rules for new homes to be carbon neutral, removal of financial incentives for the purchase of less polluting vehicles and the granting of licences for shale gas exploration.

Actions to reduce Air Pollution

This will require current and future governments to take far more effective and sustained actions than we have seen so far. The current situation is not encouraging. The National Air Quality Strategy has not been updated since 2007 and lacks ambitious targets and actions.

Any actions will most likely only be adopted if they don’t limit personal freedoms and impact on comfort and conveniences currently enjoyed by UK public.

MIT estimates total monetised life loss in the UK due to air pollution is between £60-62 billion per annum or up to 3.5% of 2012 GDP (Yim & Barrett). 1/3 of annual deaths from air pollution are attributed to imported pollution from Europe. Initiatives should be pursued to help reduce this. 2013 EU Clear Air Programme. 1979 Convention on Long Range Transboundary Air Pollution (CLRTRP). Initiatives should be also practicable, cost neutral, be supported by government, be accompanied by a programme of public information/education.

Approaches must use proven/affordable clean technologies and the public must be fully informed and ready to engage in the necessary cultural shift in attitudes and behaviours.

Reducing Pollution from Road Transport

This requires 2 broad approaches. One based on cleaner vehicles and one based on fewer vehicles with cleaner being the most likely option. Cleaner vehicles can be achieved through emissions control technology such as catalytic converters, diesel particulate filters (can become blocked if vehicle used for short journeys as heat dependent), hybrids (40,000 sold in 2015 compared to >2.5 million conventional cars). Also strategies such as reduced speed limits and cleaner fuels can be considered (even though air pollution still occurs) as well as financial incentives to buy the least polluting models (electricity or fuel cells) (the UK government discontinued such an incentive in 2015 – another discouraging sign). Issues with electric cars – air pollution still occurs to generate the electricity required to power the cars just in power stations and not by the car itself – cost (in 2015 less than 10,000 cars were sold – less than 1% of total car sales) – range anxiety (concern you will not find a recharging point). Hydrogen fuel cell – no pollutant emissions and more energy efficient (60% power conversion v 20% for combustion engine. Issues with hydrogen fuel cell – cost and hydrogen fuel availability (UK government has plans for a network of 15 hydrogen filling stations in SE England). Any cleaner vehicle approach will still cause PM pollution from tyre, brake and road abrasion. Fewer vehicles approach would require people considering their need to travel given today’s connectivity capabilities from people’s homes for work, shopping etc, walking or cycling (urban town/country planning is often focussed on motorists and not pedestrians/cyclists), car sharing and public transport (TFL aims for all single decker buses in London to be electric or hydrogen cell powered by 2020). Also economic tools can be used ie. taxing oldest, most polluting vehicles the most, congestion charging, low emission zones, car rationing during pollution episodes (allowing entry of odd and even number plated cars on certain days which will effectively halve the traffic volume). HGVs are large source of pollution.

Reducing Pollution from Power Generation

Pollution originates in more remote areas but volume is bigger. Reduction in pollution in power generation will require wholesale shift away from fossil fuel combustion. In UK last coal mine closed in 2015 and government wants to close down coal fired power stations by 2025. Dash for Gas – shift to gas fired power stations (although gas is a fossil fuel). 2 broad approaches to producing power without pollution – renewables and nuclear. Renewables are popular with public yet councils are increasingly rejecting applications for wind and solar projects (in 2014 more than half of all wind farm projects were rejected). In 2015, renewables produced almost 25% of all the UKs electricity (and just under half of this was from biomass combustion which produces pollutants). 2015 Conservative government made manifesto commitment to remove public subsidy for onshore wind power. This and other moves were widely criticised was hitting the fledgling renewables industry just as it was making good progress. Also, in the UK, public subsidies for fossil fuel energy continues. 2013 IMF estimates total global subsidies for fossil fuel use is $4.9trillion or 6.5% of global GDP and says elimination of fossil fuel subsidies would halve global air pollution deaths and raise $2.9trillion worldwide. Nuclear is expensive, creates toxic waste and puts local populations at risk and is not popular in the public mind (although actual deaths as far less than those from fossil fuel combustion). In theory the UK could generate all its power requirements using renewables but this will require proper government support which is currently lacking. Energy efficiency is an important aspect of this too but recent initiatives (Energy Company Obligation scheme, Green Deal) have been scaled back or cancelled showing there is not much government commitment. Pollution Control Technology does not eliminate pollution and is reactive, not proactive.

Reducing Pollution in other ways

Farming/agricultural emissions although we are and will remain dependent on the farming industry. Domestic fires/smoke control areas can still create/contribute to localised pollution episodes. Spare the Air type schemes. Industry emissions regulated by IPPC and are required to use best available techniques to control emissions. Air travel (LHR 3rd runway approved yet House of Commons Environmental Audit Select Committee  stated approval should only be given if pollution limits will be met. Shipping v polluting due to use of heavy oil fuels. Brandt in 2012 estimate air pollution from shipping contribute to 50,000 premature deaths each year and action still required on NO2 and fine PM.

Reactive Approaches

TFL Pilot 2010-2012 application of calcium magnesium acetate (CMA) dust suppressants to London road surfaces to reduce airborne PM10 concentrations. Saw 44% reduction in local PM10 around industrial and construction sites but not much at other roadside locations. Sheffield University PCO air purifier on roadside billboards and integrated into clothing (see links below). Tree canopies aim is to keep out polluted air but they run risk trapping polluted air at ground level.


We have a good understanding of the issues and potential resolutions concerning air pollution. #1 option for rapidly reducing airborne pollutants in the UK is zero emission vehicles. Norway wants to ban fossil fuelled cars by 2025. To be truly emission free power must be generated by non pulling means which will require government support. Poor air quality is a public health crisis now and urgent and sustained action is required going forward.

Sheffield University Links

Pollution busting flags at petrol stations

Air cleansing artwork

Charity cyclists leave trail of fresh air

Pollution busting laundry additive

The following components affect perception of IAQ:

  • Thermal Comfort
  • Humidity
  • CO2
  • Air Movement


Thermal comfort is subjective. Temperature felt is influenced by air/radiant temp plus air movement, humidity and CO2 levels. High humidity typically make people feel warmer and vice versa. Promotes mould and fungi growth and also affects emissions of VOCs due to corrosion from indoor fabrics/furnishings. High CO2 levels correlate with occupant discomfort levels. Research indicates >800 ppm negatively affects health and comfort (workplace). Typical indoor (workplace) concentrations 380-2500 ppm but can increase greatly in poorly ventilated spaces with high occupancy.

IAQ at Home

In the last 50 years more soft furnishings and carpets have been used within buildings resulting in greater chemical emissions into the indoor environment. At the start of the 20th century around 50 materials were used in buildings. Today there are around 55,000 building materials available with over half being man-made.

Significant IAQ problems have been identified with new energy efficient homes which are well insulated and generally poorly ventilated. Indeed, residents of many such homes report health complaints which can be linked to IAQ (nose-eye irritation, headache, tiredness and insomnia).

80-85% of all mould problems are attributed to humidity related (or man-made) dampness (condensation) with only 15-20% is structural related damp. (Allen 1995). Rental homes are more at risk with 1/3 of all privately rented homes not meeting the government’s Decent Homes Standard (DCLG 2014) and 66% of all rented homes containing a hazard posing a serious danger to health with damp and mould the most common (Shelter 2015). According to the BBC (The Week the Landlords Moved In) more than 6 million people in the UK are living with mould.

Click here for more information on common complaints relating to poor IAQ.

Click here for more information on indoor air pollution sources around the home.

Poor IAQ Health Concerns and Effects

Typical generic short term effects of poor IAQ include eye, nose and throat irritation, headaches, migraines, nausea, fatigue and dizziness. Typical longer term effects include exacerbation of asthma, chronic OPD and other respiratory and cardiovascular diseases, heart disorders, cancer, mental health and wellbeing conditions and reduced productivity.

There is limited data on sickness within residential homes in the UK but one can draw parallels of sickness in some commercial settings. Federspiel (2001) analysed data from 575 buildings and reported 18.4% were IAQ (77% of these were too hot/cold complaints). Fisk et al (2004) analysed a 72 person office building and found that effective IAQ management reduces annual energy costs and annual sick leave which creates a significant financial and productivity benefit.

To reduce allergies in the home, air filtration was the 4th most common strategy behind no smoking, no pets and washing sheets in hot water and followed by pillow covers, mattress covers, no carpets and use of dehumidifier (in last place). (Roy & Wisnivesky 2010)


The UK has the highest prevalence of asthma (1 in 5 people suffer). On average 3 people a day die from asthma in the UK.

NHS spends £1 billion a year on asthma treatment and care. This cost could be reduced if there was a concerned effort to reduce exposures to causes/triggers.

80% of people with asthma also suffer from hay fever (100% if their asthma is allergic). Also up to 40% of people with hay fever will develop asthma (approx 6.4 million people in 2009 (Nathan))

Hay Fever / Allergies

1 in 4 people in the UK have hay fever.

On average, those with hay fever suffer 8 serious episodes a year with each lasting approx 12 days. 50% of sufferers report impact on sleep patterns. 37% report social lives affected due to having to stay indoors. 30% report reduced exercise time and 22% report reduced quality family time due to hay fever symptoms (Allergy UK 2014). Also, hay fever affects emotions – 51% of sufferers report feeling frustrated and irritable, sluggish and slow. 40% of GCSE students with hay fever are more likely to drop a grade than those without and 70% more likely if they taking sedating antihistamines close to exams.

Public Health Concerns

Riggs (2014) conducted a survey analysing the most significant concerns of Local Authorities and H&S Practitioners. The top concern was cigarette smoke followed by air pollution from cars and factories then drinking alcohol, obesity and chemicals in food/drink. IAQ (HVAC sealed buildings) was ranked 9th and IAQ (naturally ventilated buildings) was ranked 10th out of 13 options.

An EC report in 2004 surveyed 24,798 people from 15 member countries about attitudes/risk perception toward the environment. 45% of citizens reported concern about air pollution and 35% reported concern about chemicals within everyday products. In 2011 a similar survey showed 35% of citizens reporting concern for air pollution, demonstrating a reduction in concern. Similarly, 94% of people in 2004 agreed that the state of the environment influences the quality of life which reduced to 85% in 2011 (put down to the global economic situation).

COMEAP (2011) reviewed the public’s perception of air pollution and reported “there is both a lack of awareness amongst the public regarding the links between air pollution and ill health, and a lack of understanding concerning existing air quality information”.

Odours can influence the assessment of indoor and outdoor air quality. Risk perception and the correlated personal perception of health risks of an individual are important factors to consider within the IAQ discussion (although caution should be applied to skewing overreaction to risk whereby the public demands remediation even when experts judge the risk to be low/non existent).

In 2013, the Eurobarometer interviewed 25,557 citizens across 27 member countries to understand awareness of chemicals within products we eat/drink (83%) and whether they believe the air they breathe contains chemicals (90%). Also 69% said it was not possible to completely eliminate chemical substances from our daily life and 58% said new chemical substances can help reduce the use of natural resources (although only 43% said this can contribute to a better environment).

Poor IAQ can have both physical and psychological effects on occupants. When assessing IAQ health risk must consider a) dose/multiple doses, b) exposure duration, c) vulnerability and d) perception of risk.

During inhalation, PM > 5 microns trapped by cilia in airways. PM < 5 microns enter lungs

Acute (immediate/short term) effects are often reversible. Chronic (long term) effects are often irreversible ie. lung cancer from radon, leukaemia from benzene. Allergies and asthma are by far the most common of all chronic diseases compared to heart disease, cancer and diabetes.

Sick Building Syndrome

Building related illness or allergic rhinitis affects 1 in 5 people in the UK and is caused by inhaled/ingested allergens ie. pollen, dust, mould, skin. Asthma triggers include smoke, chemical odours, NO2, dust, dust mites, moulds, pet dander etc.

Hypersensitivity pneumonitis caused by body’s immune reaction to bacteria, mould and fungi.

Legionnaire’s disease spread by the air (bacteria on water droplets)

Multi chemical sensitivities are caused by various contributors – synthetic scents, VOCs, formaldehyde, solvents, ammonia, chlorine, hydrocarbons etc.

Neurotoxic disorders which affect the brain are caused by formaldehyde and other VOCs.

Comfort and productivity are negatively affected by poor IAQ which is a recurring trend across all research. UK HSE estimates 2,500 ppm CO2 is equal to 0.8 alcohol concentration in blood which is above the legal driving limit.

Sensitive population groups include children who when exposed to high VOC levels are 4 times more likely to develop asthma than adults. Also new/expectant mothers, older adults and asthmatics are more susceptible to indoor air pollution.

In 2005 WHO predicted of the 578,000 predicted deaths in the UK, 38% would be from cardiovascular, 25% cancer and 7% respiratory disease or 70% in total from chronic illnesses. WHO also estimates a 2% reduction in chronic disease death rates would produce a $2billion economic gain over 10 years. It is estimated 18 million people suffer from a chronic disease which account for 80% of GP consultations. Improvements in IAQ and upstream support ie. biomonitoring may help reduce long term healthcare costs.

There are five main IAQ pollutant categories:

  • Moisture
  • VOCs
  • Inorganic Gaseous Pollutants
  • Inorganic Particulates
  • Organic Particulates/Biologicals


Click here on this link for more detailed information on these categories

Widespread use of fragrances and scents and its impact on IAQ

1 in 5 people in the US experience adverse health effects from synthetic fragrance exposure (15-30% of general population report sensitivity to chemicals including fragrances). Hay fever and asthma are found in 15-20% of Americans and synthetic fragrances can exacerbate these problems.

In the mid 1990s Rolls Royce recreated the smell of traditional materials from the 1965 Silver Cloud 1 model to recreate their earlier smell of unique luxury which was so successful they bottled the brand. They had become an inadvertent innovator in scent marketing.

95% of fragrance chemicals used today are synthetic compounds derived from petroleum including benzene derivatives and aldehydes which can cause asthma, cancer, affect the central nervous system, weaken the immune system and damage brain tissue. 84% of these have never been tested for human toxicity. In 1989, National Institute of Occupational Safety & Health recognised 884 substances from a list of 2,983 chemicals used in the fragrance industry as capable of causing cancer, birth defects, central nervous system disorders, allergic respiratory reactions and skin/eye irritations.

75% of known asthmatics have attacks which are triggered by perfumes.

Powerful advertising encourages us to immerse ourselves every day in these harmful pollutants.

Inhaling fragrances can trigger migraines, affect ability to concentrate, dizziness and fatigue and also contribute toward Attention Deficit Hyperactivity Disorder (ADHD). Sprays/aerosols cause substances to be dissipated into tiny particles that can be breathed into the deepest lung recesses. Deodorant aerosols can increase risk of Alzheimer’s by up to 3 times. A room containing an air freshener has high levels of p-dichlorobenzene (carcinogen) and ethanol. Mothers who use air fresheners suffer 10% more headaches than others.

Fragrance free or unscented does not guarantee the product does not contain fragrance chemicals. It may contain a masking fragrance. Labelling standards/regulations for such products do not require the content to be indicated which creates confusion with consumers who think a product may be scent free and means harmful chemicals are being dissipated without any notification to consumers.

New car smell contains a number of harmful chemicals including antimony, bromine, chlorine and lead. Exposure contribute to many acute and long term health issues. The first smelling mobile phones were introduced in 2008 and patents have been awarded for phones with a smell chip that allows sending/receiving smell messages – a possible future for mobile advertising (emotional messages via senses).

Canada and the US have recognised the impact of scents within an enclosed environment. Canadian authorities have been driving the “No Scent, Make Sense” campaign  since 2010. The US Social Security Administration recognises Multiple Chemical Sensitivity/Environmental Illness (MSC/EI) as a disability. There are some positive influences – NYC Sloan-Kettering Cancer Centre disperses vanilla scented oil to help patients cope with the claustrophobic effects of MRI testing and scents are used on the CBOT trading floor to lower the decibel level.

The issue of fragrance may be as controversial as today’s tobacco smoke issue. The debate over people’s right to smoke versus others’ right to breathe clean air could also be applied to fragrances. Second hand smoke contains >4,000 chemicals including at least 69 carcinogens. The Institute of Medicine placed fragrance in the same category as second hand smoke in triggering asthma in adults and school age children. Many of the chemicals in perfumes are the same chemicals that are in cigarette smoke such as benzene, formaldehyde and toluene.

The UK has changed to law relating to the responsiveness of the hazards of tobacco smoking which has created a paradox. Unpleasant smells such as smoke and paint fumes are unacceptable yet the use of perfumes and scent marketing is growing at an alarming rate, unregulated and using unlabelled ingredients which are harmful and are designed to suspend pollutants in the air for far longer than known hazards like tobacco smoke. See Lenor Unstoppables – current TV ads are purely about scent lasting 12 weeks yet online feedback shows the scent is made up of harmful pollutants.

Most indoor air contaminant comes from products used to contract the building or from internal furnishings yet the availability of low emission products throughout Europe is varied. Some countries have emission classification schemes. The UK has no such scheme although some companies participate in industry based schemes that produce ECO-labels for various products. In the UK, VOC content is labelled using one of 5 classifications – Minimal (0-0.29%), Low, Medium, High & Very High (>50% VOC content).

In 2007, the Code for Sustainable Homes was developed by the Dept of Communities and Local Government but the recommendations for low emission products being used in relation to IAQ and for the testing of the building prior to completion were excluded from the code without explanation. This meant the initiative failed to balance the needs of sustainable living and the health impact of the occupants.

6 top selling laundry products and air fresheners found nearly 100 VOCs were emitted and 5 of the 6 emitted more than one carcinogen with no safe exposure level.

The demands for a fragrance free workplace are following the same trajectory as the second hand smoke discussions but the movement is still in its infancy. Most organisations that have implemented fragrance free have done so reactively rather than proactively.

Ventilation Processes

Comes from Latin “ventilate” meaning “to expose to the wind”. The importance of ventilation has long been recognised in Britain. In 1696 King William III introduced the window tax which was supposedly based on the prosperity of the taxpayer. People blocked up their windows to avoid paying the tax and buildings were created with fewer windows during the increasing industrialisation and urbanisation of the period. This lead to increased health problems driven by poverty for the poorest. The tax was repealed 155 years later following campaigners arguing it had become a tax on health, light and air. Today’s well insulated, energy efficient building designs create similar problems.

The main objective of ventilation in buildings is to improve indoor air quality and influence both health and comfort by:

  • Providing suitable air for occupants to breathe
  • Reducing pollutants and waste carbon dioxide
  • Distributing thermal comfort (cooling and heating)
  • Reducing odours
  • Improving psychological effect on occupants
  • Inadequate ventilation is the biggest cause of poor indoor air quality.


Ventilation processes dilute and displace pollution but the process must bring in clean air. Therefore air should ideally be purified at the point of input. This is critical for creating a suitable indoor environment.

Liddament (2010) indicated that ventilation processes in 80% of all UK buildings was not in compliance with regulations.

How Ventilation Works

Air always moves from cold areas of higher air density to warmer areas of lower density. That’s why windows should be kept closed during winter to save energy because a heated house creates a lower air density and colder air from outside rushes into a warm house when windows are open – not the other way round. This movement is wind – the bigger the differences in temperature/pressure the bigger the wind strength. Water vapours are carried by air movements both indoors and outdoors. Typically air at earth’s surface is warmer with lower density than colder air above but sometimes inversions occur (when warmer air moves above colder air ie. warm front). Air movement over the skin causes heat loss through convection – the faster the movement to bigger the loss hence the feeling of draught. In summer air movement that creates a draught to cool is termed perception cooling.

Ventilation in Buildings

In 2014 Navigant Research reported that revenues from IAQ technologies will increase from $3.1 billion in 2013 to $5.6 billion in 2020.

Natural ventilation strategies are common in the UK , especially in older buildings, but are often ineffective and contribute to IAQ problems. There is increasing focus toward whole building mechanical ventilation strategies which are far more reliable and effective (APPG Healthy Homes and Buildings, NICE Indoor Air at Home).

Disadvantages of Natural Ventilation Strategies

  • Temperature and wind can create uncomfortable indoor conditions for occupants during poor/cold weather
  • Not suitable for noisy and polluted areas. Portable air filtration/cleaning impractical – not effective throughout property
  • Windows/vents reduce usable space, increase security risks, increase solar gains
  • Ventilation is reliant on user behaviours ie. opening windows
  • Airflows / air delivery and distribution to all areas of a property is not possible at all times with natural ventilation due to reliance on external random weather conditions. Air transfer (with doors) is especially key in this area especially with fire rated doors and is often the reason why ducted ventilation systems are required in properties of multiple occupation / offices
  • Stack ventilation does not work in summer. Internal air temps must be warmer than outside for this to work which would mean uncomfortable indoor conditions for occupants during the warmer periods of the year (in the UK).
  • Condensation and mould is a common problem in older buildings. It is important to accurately identify the source of a reported moisture problem during a survey. Either humidity related or structural.
  • Over ventilation causes unnecessary heat loss (up to 30% of total heat loss in commercial buildings)
  • De-stratification fans can reduce energy use by 20% especially in buildings with tall ceilings (warehouses)

Currently Accepted Guidelines for IAQ Investigations

  • Building Research Establishment (BRE) Protocol BR 450
  • Control of Substances Hazardous to Health (COSHH) Regulations 2002
  • The Display Screen Equipment Regulations 1992
  • The Workplace (Health, Safety and Welfare) Regulations 1992. Surveys of ventilation systems (rates and temperatures) and maintenance procedures.
  • ANSI/ASHRAE Standard 62-2001


The first step should be a preliminary walkthrough of the premises/facility to identify sources and potential contributing factors. Many IAQ problems can be resolved by a walkthrough (by a suitably qualified practitioner) saving the need for further actions – interviewing staff / taking air samples.

The walkthrough process should have a defined purpose/objective (to identify source of odour or reason for staff complaints). Proper preparation is important – building plans including HVAC schematics should be obtained, chemicals usage in the building must be determined (obtain data sheets if possible), existing complaints should be reviewed to identify trends, HVAC cleaning/maintenance/repair records must be reviewed and the walkthrough should ideally be conducted during a period when symptoms are being reported. A systematic approach using a checklist that allows photos and notes/staff comments to be stored is recommended (is an area dusty, is there mould evident, is there an odour, is there are draught, is there a disturbing noise, are eyes/nose/throat irritated or dry ?) The walkthrough should be started where the symptoms have been reported or at the inputs to the HVAC system. Walkthrough findings should be stored for future retrieval/comparison and after the walkthrough a review should be performed identifying follow up actions.

If the walkthrough is inconclusive interviews should be conducted with occupants/those who have reported complaints to gather more specific information about the IAQ problem. All responses should then be evaluated to help identify sources/locations, patterns of symptoms, timing/spatial trending of complaints (cyclical) and compared with known information of HVAC operating cycles etc.

Air Testing or Sampling

Testing or sampling is affected by different factors including concentration levels, fluctuations during the sampling period, temperature and humidity during the sampling period. Cost and time required for interpretation of results are also important considerations. Methods and instruments used for measurement should be carefully evaluated. The testing/sampling process should comprise the following general phases:

A planning phase incorporating aims and objectives, targeted compounds based on potential sources, products used, history and location of the building and known contaminants. Sampling methodology may comprise two approaches based on overall environmental or personal exposure. Environmental sampling may comprise an initial appraisal including a qualitative test of staff and a snapshot quantitative test using monitoring instruments which will identify top line concerns. This can be followed by more detailed quantitative survey/s analysing worst case scenarios (max occupancy, hottest temperature) that is more focussed on occupant’s exposure (especially relating to carcinogens etc) and looks at the relationship with building and activity processes, control measures, maintenance/servicing records, health complaints and previous monitoring activities. Detailed surveys should include time weighted averaged measurements taken over varying periods. Personal Air Sampling follows a similar pattern but involves sampling the near an individual’s breathing zone. Sampling can be passive (typically using low cost detector tubes) or active using calibrated detection/measurement equipment.

In the workplace environment, a single sample is rarely sufficient to assess indoor air quality as the air quality will change within seasons, times of day, occupant density, ventilation status and occupant’s activities. Therefore it is recommended that multiple samples over a number of time periods (hours, days and even weeks or months) are taken to provide trending data.

HSE EH40 provides workplace exposure limits and provides valuable guidance for understanding the health risk of hazardous substances. Note many of the limits in this document are far higher than IAQ Rating Index because they describe maximum exposure limits rather than the optimum environment.

A pre-test/sampling walkthrough phase is to inspect the layout, ventilation status, potential contamination sources, occupancy density and activities, locate odours/concerns and identify potential interference with the sampling process.

The test/sampling phase requires data gathering on sampling points (on floor plan), occupancy density and activities, HVAC activities, evidence of odours, moisture indicators, potential contamination sources and behaviours (windows open, vents blocked etc). Actual air samples should be taken from the breathing zone of the occupants (1 metre above the floor).

Appropriate quality control measures should be taken for sampling including ensuring instruments are properly calibrated. Samples from non affected areas and outdoor air should be taken to allow for comparison. Care should be taken with any detection tubes to prevent cross contamination.

Following the sampling a process of data analysis should be conducted to identify patterns/trends. Also quantitative and qualitative data should be charted together over time ie. Correlation between occupant comfort and CO2 levels.


Concentrations measured in PPM/PPB for gases – 1 ppm is equivalent to 1 party balloon within 50 3 bed houses – and mg/m3 for solids – 1mg/m3 is equivalent to 1 teaspoon of dust within a football field covered with dust to 1m in height. 1 person inhales on average 10 litres per minute of 4,800 litres per day which occupies a space of 4.8 m3. Calculating a concentration can provide information about the level of exposure.

Workplace exposure limits are subject to 2 time weighted averaging periods – LTEL – Long Term Exposure Limit – 8 hour reference period and STEL – Short Term Exposure Limit – 15 min reference period. These a max limits so practitioners should be achieving the lowest practical levels.

Exposure is calculated by multiplying amount of measured substance by the time exposed (in hours) and then divide the result by either the 8 hour long term exposure rate (LTER) or or the 15 min (0.25 hours) short term exposure rate (STER) depending on how long the sample was taken for.

For example: Exposure of 7 hours 20 mins at 0.12 mg/m3 with 40 mins at 0 mg/m3 = 7.33 hours / 8 hours (LTER) = 0.11 mg/m3 time weighted average over the 8 hour period. Exposure of 15 mins at 0.68 mg/m3 = (0.68×0.25) = 0.17 hours / 0.25 (STER) = 0.68 mg/m3.


NOTE: STEL always take precedence over LTEL. When STEL is not given it should be assumed it is 3 times the LTEL value.

Types of HVAC system

Constant Air Volume (CAV) – constant air supply that is heated or cooled to meet needs. There are 3 types of CAV system:

  • Single Duct – One distribution system, one air handling unit
  • Reheat – Same as Single Duct except reheat coils are installed within the ductwork for further temperature control for each room
  • Dual / Double Duct – Cold and warm air is circulated through parallel duct system. Thermostatic dampeners control the proportion of warm/cold air delivered.


Variable Air Volume (VAV) – more energy efficient whilst providing thermostat controlled variable (hot/cold) airflow

Demand Controlled Ventilation (DCV) – sensors control ventilation according to temp, CO2 etc and switches allow users to override HVAC functions according to need.

Commercial ventilation uses air change rates (l/s) per person. Rates lower than 10 l/s per person are associated with poor air quality and increased health issues whereas rates between 10 and 25 l/s per person are associated with reduced adverse symptoms.

Air Cleaning or Purification

There are 2 types of air cleaner – Arrestors and Non Arrestors. Arrestors trap particles, Non Arrestors change the characteristics of the particles.

Filter and electrostatic systems are Arrestors but require maintenance and can be affected by humidity, moisture and temperature. Also electrostatic systems are not as effective as many filter systems and can produce ozone. HEPA filters remove 99.97% of contaminants at 0.3 microns. Activated charcoal or carbon inserts can remove fumes, vapours and odours.

Non Arrestors include Ionizers, UV/PCO and Gas Sorption systems (Note Better Indoor Advanced Air Purification systems are examples of Non Arrestors). Ionizers electrically charge particles so they can be captured by an attractor plate. UV systems use UV light to deactivate bacteria and viruses to prevent them from reproducing and have no effect on inorganic PM (traffic soot). Banks of UV lights are typically installed INSIDE ductwork close to cooling coils and drain pans to prevent barteria/mould growth with studies showing a 99% reduction in microbial contaminants on exposed HVAC surfaces (although in airstreams this reduces to 25-30%). UV systems can be made more effective by reflecting the UV light within a chamber which slows the airflow and protects users against UV exposure. PCO systems are similar in that they use UV light but with a photocatalyst (usually titanium dioxide) to create oxidants which physically destroy contaminants by changing their molecular composition. UV light causes titanium dioxide to free electrons at its surface creating hydroxyl radicals which attract VOCs and bioaerosols to the surface where they are oxidised by a photocatalytic reaction into carbon dioxide and water vapour. PCO systems should be checked to ensure they do not produce harmful by-products such as CO, chlorine, H2S and ozone when in the presence of chlorinated VOCs. Gas Sorption systems comprise two main types – Adsorption and Chemisorption. Adsorption results from the physical attraction of gas or vapour molecules to a small pore surface as a result of nuclear attraction forces (van de Waals) where they become trapped. Adsorption occurs more readily at lower temperature and humidity. Activated carbon is the most common adsorbent used in HVAC systems and can remove most hydrocarbons, many aldehydes and organic acids. Adsorption is ineffective against low molecular weight gases such as aldehydes and ammonia. Adsorption filters require frequent maintenance. Chemisorption occurs when gas or vapour molecules react with sorbent material or agents impregnated into the sorbent forming stable compounds that are bound to the media as organic or inorganic salts which are then broken down and released into the air as CO2, water vapour or a more readily adsorbed material.

Maintenance of HVAC Systems

L24, the ACOP Workplace (Health, Safety and Welfare) Regulations 1992 specifies under Regulation 6 “mechanical ventilation systems (including air conditioning systems) should be regularly and adequately cleaned. They should also be properly tested and maintained to ensure that they are kept clean and free from anything which may contaminate the air (p18). Air filters must meet EN779:2012 standards. Dust masks should meet FFP3 standards and should be worn when performing maintenance.

Cleaning HVAC Systems

24,000 accidental fires each year in non domestic buildings are attributed to cooking appliances. 80% of kitchen extracts are never cleaned. Regulatory Reform (Fire Safety) Order requires building operators to address potential hazards via risk assessments and ventilation systems should be incorporated. Insurance companies are now specifying requirements and regular cleaning programmes for HVAC systems (3-6 monthly) are now common. Dirty fans and filters increase energy costs by 35%. See B&ES TR/19 Guide to Good Practice – Internal Cleanliness of Ventilation Systems. Also CIBSE Guide B3 and BS EN 15780 Ventilation in Buildings – Ductwork – Cleanliness of Ventilation Systems states “the importance of the frequency of inspections and levels of cleanliness required in order to maximise efficiency, lengthen the system’s service life and achieve optimum levels of air purity for the building, in line with its intended use”.

Risk assessments should be conducted prior to any cleaning work to identify risks such as load bearing areas of ducting, access points, isolation switches, entrances to confined spaces, control measures for equipment and substances used and any permits required. Cleaning technicians should be qualified and work to the standards of TR/19 and BS EN 15780. BE&S can provide details of experienced contractors.

HVAC system cleaning should incorporate the entire system and not just ductwork including:

  • Diffusers
  • Plenums and ceiling spaces / voids
  • Ductwork
  • Fire Cladding / Board
  • Dampeners
  • Fans
  • Heating and Cooling Coils
  • Filters
  • Air Handling Unit
  • Areas likely to be contaminated include:
  • Coils
  • Blowers
  • Mixing Boxes
  • Dampeners
  • Duct Transitions
  • Return Ductwork and Exhaust


Water colour in drainage trays may indicate the following:

  • Green – Copper corrosion (pipework / battery tubing)
  • White – Aluminium corrosion (battery tube)
  • Black – General dirt, faulty filter allowing air bypass, system overdue for thorough clean. Urgent action required.
  • Brown/Red – Iron/Rust corrosion within (metal) duct. May indicate Legionella. Urgent action required.
  • Bubble/Slimy – Microbiological activity within duct. May indicate Legionella. Urgent action required.


Cleaning should be performed when a visual inspection indicates excessive particulate debris or microbiological growth within ducts, dust discharge from diffusers or water collection/damage in ducts/pans. Other procedures that can be use in cleaning include Surface Comparison Testing (compare test surface against control surface after 4 brushes), NADCA Vacuum Test, Deposited Thickness Test or Gravimetric Tape Sampling. Manual/Vacuum cleaning methods are used. Surface Treatments should only be performed if absolutely necessary and on non porous surfaces. Note any porous materials containing fungal growth should be discarded and replaced. After cleaning, an inspection should be performed to verify. TR/19 provides guidance on acceptable dust accumulation levels and CIBSE TB26:2000 on microbial counts. Records should be kept for any areas that could not be cleaned for at least 5 years.

Common Errors in HVAC Installations

  • Air supply input situated too close to outdoor contaminants – HVAC exhaust point, rubbish areas, roads etc.
  • Ducts/Impellers/Filters not cleaned/replaced regularly which reduces airflow/ventilation efficiency of system/fan.
  • Predominant use of flex duct – optimises resistance within duct runs
  • Ductwork not airtight, especially around connections allowing air to escape system
  • Supply / Extracts not balanced resulting in increased CO2 (levels above 1000 PPM means ventilation is inadequate), increased or decreased RH etc
  • Closed / blocked diffusers/dampeners reduces air supply
  • Changing room layout after HVAC system has been installed creating imbalances and rendering thermostats inoperable.
  • Increased occupancy or equipment not reflected in changes to HVAC operation

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