A couple of random thoughts to add to the mix ....

First, the ever-growing list of chemicals we use indoors for various purposes present a risk in the form of "trigger agents" to asthmatics and people with pulmonary diseases and/or allergies. Many of these chemicals are so ubiquitous that it is difficult for patients to escape them in both environments they control (their own homes) as well as environments they don't control (work, school, shops, etc).

Second, for the past year or so I have taken up 3D printing in my home and have discovered that some of the plastics that are used (notably ABS, acrylonitrile butadiene styrene) and to some extent PLA (poly lactic acid), release VOCs and nanoparticles during the printing process. While patients obviously should avoid these fumes and aerosols, the risk for otherwise healthy people of reacting adversely or developing disease related to these emissions probably needs study. Further, there are no standards relative to this issue; at least for hobbyists.

Interesting question, Francesca.

I have the impression that indoor air quality has been an important issue for a long while. For many years there has been many approaches, either atwork environment but also at locations like schools and homes. Recently I have noticed a growing interest in the evaluation of the presence of "new pollutants" such as EDCs present in materials used at homes and schools.

As usual, evaluation of the presence of harmful or dangerous components is the first step to take, in order to have a clear risk assessment. From there, evaluations of exposure, possible mechanisms of actions of exposure to complex mixtures and many other variations would be explored.

It will be interesting to see what others think about this.

I think nanoparticles is perhaps the biggest challenge. These particles are so small that they penetrate into buildings. If you happen to work or live near a highway or major roads, chance are that you are breathing enormous amount of nanoparticles. These particles penetrate the blood barrier and affect the whole body with a myriad of health problem (neurodegenerative, cardiovascular, inflammation, oxidation etc etc.).

Look at the TV program on nanoparticles made in Canada

Something In The Air

Sunday, February 17, 2019 at 8 PM on CBC-TV

https://www.cbc.ca/natureofthings/episodes/something-in-the-air

Thank you, Ernesto and Alain, for the reply.

As scientists, we will be asked to provide scientific answers to several questions about indoor air quality. These include a full characterisation of (new?) pollutants and underlying toxicology mechanims, role of infiltration (from outdoor to indoor), pollutants' lifetime and ageing processes, assessment of exposure and levels, possible sources, etc.

Of course, ultrafine particles, combustion, and mental health will be an issue here.

We have gained a lot of experience from outdoor air quality studies, indeed, but still this is not enough, I do believe, not for outdoor not for indoor ai quality.

Also, it appears to me, that the regulatory framework is still far from being well-established.

Finally, note that the topic is sensitive and relevant for working environments and schools, beyond private homes. A further challenge.

May I ask your view on this?

I think formaldehyde which is emitted by indoor furniture, paintings etc. is a source of concern inside home (even if some agency minimize their potential impact).

Article The effects on asthmatics of exposure to a conventional wate...

https://www.ncbi.nlm.nih.gov/books/NBK138711/

The responsible for indoor air quality are usually not government agencies but rather the owner of buildings (at least in Canada). No regulation exist really except for workplaces which is under the Canadian Labor Code.

I suspect that in many other countries, governments are not responsible for indoor air quality. In US, EPA (Environmental Protection Agency) have some regulations for indoor air quality. I do not know for other countries.

But yes, I agree indoor air quality should be regulated. In addition, a lot of moulds are found in school and who knows what else.

Internal Air Quality (IAQ) is a term that refers to the quality of air inside and around buildings and installations, especially those related to the health and comfort of the residents of the building. The internal air quality of gases (including carbon monoxide, radon and volatile organic compounds), particles, bacterial contaminants (mildew, bacteria) or any overall stressors or energy that can cause adverse health conditions can be affected. Source Control, Filtration and Use of Ventilation Mitigation contaminants are the main ways to improve indoor air quality in most buildings.

The internal air quality of gases (including carbon monoxide, radon and volatile organic compounds), particles, bacterial contaminants (mildew, bacteria) or any overall stressors or energy that can cause adverse health conditions can be affected. Source control, filtration and use of ventilation to mitigate contaminants are the main ways to improve indoor air quality in most buildings.

Without any doubt, the evaluation of pollutants, “new” and “usual suspects”, is something that must be addressed. Of course, in the richest countries the attention is mainly on "new" and "sophisticated" pollutants, such as EDCs and nanoparticles that may come from outdoor or indoor sources. This is of special interest in countries like Sweden, Norway, Denmark, Finland, Canada and many others where the populations spend large proportions of their time indoors, without natural ventilation and therefore the indoor sources of pollutants have great importance and are considered as something to be studied in detail.

In contrast, the poorest countries are those still having the highest levels of indoor pollutants, those who have been studied for decades, coming from open fires or very low efficiency stoves. Therefore, the challenges ahead are different depending of the region and economic development. As scientists concerned about the exposure and adverse outcomes related to indoor exposure to pollutants, the challenge is monumental in reducing the exposure to very nasty, already known pollutants in countries where millions upon millions, mainly women, get exposed, having a large impact on life expectancy. On top of that, we must keep evaluating the presence of “new” pollutants and their potential deleterious effects.

Dear Professor Costabile,

Indoor air quality is not only interesting but also an extremely diverse topic and i believe it is a serious issue. Starting with differences in indoor air quality in urban, rural and semi-rural settings. Followed by the differences in low, middle and high income countries. Thereafter, the individual housing characteristics (the material used for building/painting the inner walls, the flooring material etc.) the fuel used for cooking or heating and type of persons residing in the house would also influence the changes in indoor air quality. The role of bio aerosols and inflammation in particular would be interesting to be analyzed under different settings and at a similar time period.

Thank you all for the reply.

I'd like to know if anyone can suggest any benchmark for indoor air quality (i.e., the latest review paper and/or regulatory framework in progress).

I do suspect that (as Alain said) there is no regulatory benchmark except (perhaps) for workplaces, isn't it?

In Canada, indoor air quality is the responsability of the building owner. At workplaces, the employer should follow the Canadian Labour code which does not include nanoparticles, formaldehyde, ozone and many other pollutants.

So we have a problem.

A couple of random thoughts to add to the mix ....

First, the ever-growing list of chemicals we use indoors for various purposes present a risk in the form of "trigger agents" to asthmatics and people with pulmonary diseases and/or allergies. Many of these chemicals are so ubiquitous that it is difficult for patients to escape them in both environments they control (their own homes) as well as environments they don't control (work, school, shops, etc).

Second, for the past year or so I have taken up 3D printing in my home and have discovered that some of the plastics that are used (notably ABS, acrylonitrile butadiene styrene) and to some extent PLA (poly lactic acid), release VOCs and nanoparticles during the printing process. While patients obviously should avoid these fumes and aerosols, the risk for otherwise healthy people of reacting adversely or developing disease related to these emissions probably needs study. Further, there are no standards relative to this issue; at least for hobbyists.

Indoor air quality is definitely a growing concern. A lot of commercial companies are now building indoor air quality monitors but mostly are based on CO2 values. Particle concentrations are often not taken into account specifically for indoor calculations while they should now be considered a major concern due to its toxicity and hazardous outcomes.

Based on this concept I am doing a research in developing a system for indoor particles too which will definitely give us a better idea how these particles are effecting people and the indoor environment.

Thanks alot, Alain, Michael, Syeda, for the reply.

Dear Francesca,

as most people have mentioned already, there is no legal regulation of indoor air quality in private spaces in most countries. (I am actually not aware of a single country.) Private spaces are usually protected by constitution. Instead, there is usually regulation on the chemicals that can legally be put into products sold on the market, such as REACH in Europe. Products with indoor relevance include, for example, building products like flooring, finishing, varnishes, but also furniture, consumer devices, cleaning agents, and fragrances. However, the regulation of chemicals in products is often not sufficient to safeguard a "healthy" indoor air quality, because the latter depends, in addition, on many factors like the properties of the building (ventilation, sorption capacity) and personal behaviour/habits.

As a way out, the German Environment Agency established the German Committee on Indoor Guide Values (AIR) a while ago. AIR has since derived plenty of so-called 'guide concentration values' for a healthy indoor air. Those guide values are specific for each chemical compound, and represent the level, at which no health effects are known even for life-long exposure. (The collection includes guide values for formaldehyde, benzene and CO2, of course, but also for many other well- known and emerging VOCs.) The 'guide values' are derived on a rigorous and standardised basis from the evidence provided in available toxicologial studies. Since they refer to the environmental conditions found in private homes, and also consider susceptible sub-groups, the guide values are typically much lower than the permitted workplace concentrations, which reflect the exposure of healthy adults during workshifts. In Germany, the guide values have become quite useful as a benchmark for the assessment of indoor air quality in any individual observed case study. The system and the values are reported here: https://www.umweltbundesamt.de/en/topics/health/commissions-working-groups/german-committee-on-indoor-guide-values. If you need more information, I can provide corresponding materials.

Kind regards, Wolfram

Dear Wolfram,

how nice to hear from you!

Thanks for the reply: very interesting.

I wonder if there is a recommendation relating to the partitioning of those contaminants between particle- and gaseous- phase, and in particular relating to ultrafine particles and black carbon.

I understand that the German Committee on Indoor Guide values (AIR) recommends that "indoor PM2.5 concentrations should be as low as possible", and in any case below the WHO 24-h mean guideline level (e.g., Fromme et al. 2019 - doi: 10.1016/j.ijheh.2018.12.012).

However, I wonder if there is a work under way in this area.

Hope to hear from you soon.

F.

Dear Francesca,

may I draw your attention to the following COST Action: https://indairpollnet.eu/

Best,

Sascha

Dear Sascha,

thanks a lot for the message. I shall contact you personally to have more information about it.

Indoor air pollution is one of the most important topics in toxicology. Humans now spend most of their time indoors so they are exposed to the dust and its components daily. In fact, my colleagues tried to address this in 2018. They Isolated and Characterize Respirable Particle Fraction From Residential House-Dust (PMID: 29172162 DOI: 10.1016/j.envres.2017.10.049). You can read their important paper and its methodology.

Thanks a lot, Ali, for commenting on that.

In epidemiological studies of air quality on health, the impact of indoor air quality is often ignored (either indoor AQ at home or at work) which provides considerable biases to these studies. My understanding is that it is not really taken into account and only outdoor air is used as an input to these studies (e.g. in air quality indeces).

Thanks a lot, Alain, for the reply. Indeed, your point is very interesting: how should epidemiological studies in the indoor air environment be designed? My understanding is that the overall exposure in this case (long-term? Chronic?) should be based on the proper combination of both outdoor and indoor exposure. Please, correct me if I am wrong.