Another indoor air quality conundrum

Yesterday, the UK government announced that all remaining restrictions relating to Covid-19 are to be relaxed on July 19th. There will no longer be a requirement to work from home when possible (something that seems to have been gradually ignored by many organizations for weeks already) and schools can abandon bubbles and even mask wearing and social distancing.

To mitigate some of the effects of increasing infections and the removal of passive measures such as masks and distancing, better ventilation of buildings is encouraged.

One way to measure ventilation is by using a proxy measure of carbon dioxide concentration, and that is pretty easily achieved with IAQ monitors. Carbon dioxide concentration is a good proxy measurement for ventilation as the higher the levels of CO2, the fewer air changes are taking place. If CO2 levels are high, then increasing ventilation is a good option. Not only will it have an impact on virus transmission, but it will also improve cognitive ability and reduce the risk of drowsiness. High levels of CO2 are very much associated with poor productivity.

Awair Omni OAQ monitor

The easiest way to improve ventilation is to open some doors and windows. In most schools, that is the only way to do it – very few schools have complex HVAC systems that can adjust ventilation rates and still pass air through filters.

If you have an IAQ monitor that measures a range of parameters, such as particulates and VOCs as well as CO2, then as soon as you open a window, you might discover that other pollutants increase rapidly – and then what are you going to do? Balancing the health risks of the different contributors to poor IAQ is hard enough already, without the added complications of a nasty virus

Many schools, especially those in urban areas, as well as office buildings, are situated near busy roads and particulate pollution especially is known to be very damaging to respiratory health. Measurements of particulates near roads are sometimes way above safe limits and high concentrations of fine particulates can kill or seriously damage health.

Photo by thevibrantmachine on

So, here is the puzzle that has to be solved. Will opening windows to reduce the risk of ill health due to airborne viruses (such as Covid-19) cause a bigger impact on health by letting in a whole load of other pollutants, especially fine particulates?

There are, of course, some things that can be done to reduce the amount of particulates getting into buildings.

The first is to reduce them at source. In urban areas, the main source is traffic, especially traffic using internal combustion engines. The rapid increase in electric vehicles is certainly going to help, but it will take many years before they are off the roads completely, and the most polluting types of vehicle are the hardest, at the moment, to electrify (big goods vehicles).

Next, you can try and reduce the chances of those particulates getting inside a building with open windows. This is not going to be easy, but there are some effective measures, and they are mostly green.

Green walls, green screens, climbing and scrambling vegetation, trees and hedges are all capable of trapping large quantities of particulates on their foliage, and have an impact on urban heat islands too.

A Mobilane Ivy screen trapping particulates and keeping the noise down

Trees, hedges and plants like ivy are actually quite cheap too, and they are self repairing. They also reduce noise and look good too.

In the short term, using ventilation to flush out viruses (along with excess CO2) is going to be better than leaving windows closed and minimizing the ingress of fine particulates, but that is not a viable long term solution. Ideally, we should always have good ventilation to flush out viruses (it would be a good idea to use ventilation against all respiratory viruses, not just Covid-19), but if that is the case, we must do more to prevent other pollutants getting inside buildings. Vegetation is going to help a lot, but removing the source of those pollutants has to be the ultimate goal.

An indoor air quality conundrum

Something smells good

I have seen a notable increase in the number of posts on platforms such as LinkedIn extolling the benefits of ambient scenting – the addition of a high quality fragrance to the air inside buildings to make them more appealing (this is not the same as the use of air fresheners, no matter how sophisticated, to mask malodours in settings such as washrooms).

This is actually a subject I know quite a lot about (I’ve had a bit of a love/hate relationship with the subject since about 2007), and I can certainly vouch for the effects that scenting has on mood and the perception of the qualities of a space.

Ambient scenting can be used to reinforce brand values, make a place appear more luxurious and has even been shown in some experiments to reduce anxiety in healthcare settings. Some smells are very good at increasing the perception of good air quality – think of those fragrances that smell especially clean, fresh and hygienic.

Ambient scenting also has a role to play in biophilic design – potentially a very big role. Our sense of smell is our most primitive and we often react to a smell before we are consciously aware of it. Scents redolent of nature, when combined with appropriate visual and textural stimuli certainly add an extra dimension to a space – when our senses are stimulated congruently, our surroundings make more sense to us.

The technology of scenting is highly sophisticated (far more complex than an aerosol can or a scented candle) and is often programmable and even web-connected. Furthermore, the actual amount of fragrance chemicals released into the environment is actually really tiny – just enough to be perceived (this is especially true of nebulising systems). Some systems are designed to scent whole buildings through the HVAC infrastructure, with the fragrance oils introduced directly into the air handling unit.

Cleaner air

As well as spotting the increase in the number of posts about the benefits of scenting, I have also seen an increase in posts about air purifiers. This is clearly a hot topic. Even before the Covid-19 pandemic, poor air quality was high on the agendas of public health officials and building managers. Poor indoor air quality is associated with symptoms related to sick building syndrome and can, at times, pose a risk to the health of building occupants.

The development of new building standards, such as RESET, and the incorporation of IAQ monitoring standards into schemes such as WELL has brought not only management of IAQ, but also the monitoring and reporting of IAQ to the fore.

This is a good thing, and a subject that I have touched upon before. New research has shown that an increasing number of people are expecting more transparent reporting of IAQ in offices, especially amongst those facing a return to regular office work as pandemic restrictions ease.

Air purifiers are interesting products as well. Different systems employ a variety of technologies to remove fine particulates and remove, or breakdown, volatile organic compounds (VOCs).

Unfortunately, as far as I know, none of these air purifiers is able to distinguish between harmful, or unwanted, VOCs and those that smell nice and which were put in the environment deliberately.

The conundrum

The issue that is puzzling me is that many of the companies promoting ambient scenting are also promoting air purifiers, and this strikes me as strange. What drives this corporate cognitive dissonance?

If a company is selling an air purification system, one would hope that their sales people are able to present the features and benefits with some degree of conviction and be able to explain how an air purifier works and what it does to the chemicals circulating in the air.

Likewise, a sales person selling a scenting service should be able to explain how adding more chemicals to the environment can improve the users’ experience of a building (a scenting machine is a product that is designed to actively put more chemicals – no matter how safe they might be – into the environment). I’m not trying to be confrontational here – buildings that smell nice can certainly make using that space more enjoyable. People use fragrances all the time in homes and, of course, on their bodies.

It is quite possible that in situations like these it is likely that the left hand is unaware of what the right hand is doing. The people selling air purifiers may not be the same people that are selling ambient scenting (even if they work for the same company).

Furthermore, the purchaser of the scenting system might not be the same person as the purchaser of an air purifier (even if they work the same customer). If it is the same purchaser, that person now has the burden of potentially making an uninformed choice: is it reasonable to expect a customer to know that the air purifier will eliminate, or at least reduce, the efficacy of their expensive ambient scenting system?

One mitigating argument is that scenting systems are supposed to be situated where air purifiers aren’t. If that principle was universally applied, then there might be no issue – and maybe that is the norm. But I am not convinced that is always the case, especially with an increase in sales of portable air purifiers. These, by their nature, are going to be moved around and quite possibly moved into spaces where there is a scenting system in place. It is also possible that the person specifying the air purifier is unaware of the the presence of the scenting system.


I think it is unlikely that companies are deliberately selling both services to be used in the same spaces. There might be a short-term gain by doing so – the customer is going to get through a lot more expensive fragrance than might otherwise have been the case – but I doubt it would take very long for them to spot the problem.

Being a benevolent sort of person, I suspect that the poor sales people flogging air purifiers and scenting systems might not be sufficiently aware of the other products and services offered by different parts of their company (although their marketing departments ought to be). And if they are unaware, it makes it harder for them to help their customers make informed choices. This is clearly an opportunity for some training to be given (and if you are one of those companies facing this dilemma and would like some training developed for your sales and/or marketing people on this matter – please get in touch and I might be able to help you).

If sales people are actually selling both types of product, especially to a purchaser that might be responsible for buying both types of product, then there is an even greater need for some education to ensure that they remain credible and really understand the needs of the customer.

Indoor air quality management for home-based office workers

As we move deeper into autumn and, with the knowledge that for very many people, working from home will be commonplace for the foreseeable future, the issue of air quality becomes more important.

‘Good’ indoor air quality is very hard to define, and very subjective. There are some pollutants that must be considered as potentially damaging to health, such as fine particulates (PM10, PM2.5), various oxides of Nitrogen (often written as NOx), a cocktail of volatile organic compounds (VOCs) and ozone. These are often generated outside of the home, especially as combustion products or from vehicle emissions, although some are also produced by domestic activities, such as cooking and cleaning.

Local air quality is affected by a whole host of factors, such as proximity to roads or industry, and also the weather. In the autumn and winter we experience storing winds, which are good for dispersing and diluting pollution, but also very still days when pollutants can be trapped in the lower atmosphere where they build up to risky levels. This air also finds its way inside our homes – more so than in offices, which are often quite air tight and fitted with sophisticated air management systems (usually referred to as HVAC systems: heating, ventilation and air conditioning)

Something else to consider is the amount of pollution created in the home, especially in the kitchen. Cooking produces a whole host of volatile organic compounds. Particulates and combustion products are also produced – especially if you are prone to burning food.

Now, of course, we have an additional factor to consider. Airborne infections spread on aerosols (the fine droplets created when coughing or sneezing), whether as a result of Covid-19, or the common cold, will have to be factored into the way that homes are heated and ventilated.

Health advice recommends high levels of ventilation to reduce the risk from aerosol infections, but in a house, that means opening doors and windows (rather than adjusting a complex HVAC system), and that might mean letting expensively heated air out and polluted cold air in.

On the other hand, it also means letting cooking fumes and carbon dioxide out, so it might be possible to maintain a healthy balance. But how would you know?

Air quality data

There is an old saw that says that you can’t manage what you can’t measure. With air quality, that is especially true. Pollution is pretty-much undetectable by the senses (you might smell fumes, but you couldn’t possibly estimate the concentration), so the only way to know for sure is to have access to data.

Local outdoor air quality data can be found on various web sites, and these are pretty accurate within a few miles (but generally not down to street level). A good example is

This screenshot shows the air quality around my location (marked by a red dot), with my closest monitoring station shown in the box. However, local knowledge tells me that the air quality in Belvedere – an urban area – is likely to be a little different from my semi-rural location (although on the occasion of this reading, the whole area looks to have very similar air, and pretty good, air quality.)

Indoor air quality is a different matter, however, and the only way to know what is in the air inside your house is to measure it.

There are very many indoor air quality (IAQ) monitors on the market for domestic use. Some resemble toys and others look a bit like medical devices. Others are a little more subtle.

With IAQ monitors, the quality of the data depends very much on the quality of the sensors, and that can vary. There is some truth that you get what you pay for and if you can afford it, spending a little more will get you a better monitor.

Some IAQ monitors connect via WiFi and will send data to an app on your phone, and some can even be connected to smart home devices, so if a certain threshold is breached, it can switch on a fan, or an air purifier or dehumidifier, for example.

This is an example of a domestic IAQ monitor (the Awair Element) that displays IAQ data on the front of the monitor and on an app.

What should be measured

As a minimum, a domestic IAQ monitor should be able to measure total VOCs, fine particulates, temperature and humidity. Carbon dioxide measurement is also useful. The monitors should also be able to display an overall air quality score as well as the individual parameters, and that can help the user to decide what to do (e.g. open or close a window).

VOCs and fine particulates (PM2.5) can be quite dangerous. Carbon dioxide less so, unless at extreme concentrations. However, carbon dioxide is worth keeping an eye on, as at concentrations well below harmful levels, it can make you feel drowsy, have an effect on the ability to concentrate and can impair cognitive functions. The source of carbon dioxide is mainly people, and it doesn’t take long for levels to increase in a well sealed building with a few people in it.

Using data to help you make decisions

There may be times when you see the various IAQ parameters on your monitor telling you different things about the overall IAQ. For example, you may notice that particulates and VOCs are quite low, but carbon dioxide is increasing. Opening a window will certainly reduce the concentrations of carbon dioxide, but may result in the other pollutants increasing as outside air is let in. However, unless outdoor air quality is really bad, it is unlikely that in the short time a window is opened to flush out the carbon dioxide that concentrations of the other pollutants will rise to concerning levels.

Knowing about IAQ will help you make informed decisions about how to manage your indoor environment, such as heating, ventilation, use of plants or avoidance of certain chemicals or activities – will you work in the kitchen while someone else is frying bacon or burning toast, for example?
Without the data, you wouldn’t know.

IAQ monitoring as part of the home-workers office kit

If you are used to working in an office, there is a good chance that IAQ is already monitored – it will be used to help manage HVAC systems. If your office has a wellbeing certification, such as WELL or RESET, you should find that IAQ data is shared with all the users of the building.

Knowing about IAQ in an office can be empowering and be useful to help building managers understand local issues (i.e. your immediate surroundings), as well as what is going on in the whole building.

As a home worker, this information is also very useful, as it will help you manage your working environment and keep it as healthy as possible.

Working with my colleagues at Fusion Spaces, we are developing the WorkFreeTM home workspace assessment method to look further into managing home office space to be as healthy, safe, comfortable and empowering as it can be.

For further information about WorkFree ™, please contact us by email or take a look at the web site.