Ignorance Isn't Bliss

Seven years ago a nine year old girl, Ella, died. It was recently concluded that air pollution played a role. This was not in China, India or Pakistan, but rather south-east London. According to [1], the mom was never informed about the dangers of air pollution, despite living in a particularly polluted area and her daughter having asthma. If she would have known, she would have acted. Perhaps Ella would have still been alive.

It is no news that air pollution is dangerous, especially for people with respiratory illnesses, such as asthma. WHO rated air pollution, along with climate change, as a top 10 threat against global health 2019 [2]. Global Action Plan conducted a survey [3] which showed that people are indeed concerned, but the majority do not know where to get advice or information.

One of the main motivations for starting BabyFriendlyAir was to indirectly save lives. Inspired by, among others, SmartAirFilters, we want to spread awareness and share information that can be useful for especially those less privileged - who are indeed often the most affected by air pollution [4]. As Ella’s mom said, if she would have known, she would have acted. We believe this is true for many people around the world.

Dangers of Air Pollution

There are plenty of articles discussing the dangers of air pollution. Damian Carrington gives you a good overview in [5] of how air pollution can affect every organ in your body, for instance your brain, skin or fertility. Unicef describes [6] how air pollution affects brain development of young children, even before they are born. In [7] air pollution’s exacerbating effect on chronic respiratory diseases, such as asthma, is discussed.

Figure 1. 50µg/m3 in Berlin, accompanied by visible smog.

Berkeley Earth has tried to make air pollution a bit more concrete by calculating how it translates to cigarettes [8]. They equate one cigarette per day with 22µg/m3 PM2.5. Naturally, this is just an estimate. Furthermore, they show that for instance in Beijing the air pollution can be estimated to equal smoking 25 cigarettes a bad day. In the EU, the average would be 1.6 cigarettes per day. If you’re a smoker, perhaps you think that less than 2 cigarettes a day isn’t too bad. But, remember, also children, babies and people with respiratory diseases get those cigarettes, whether they want them or not.

Protect Yourself

There’s a lot you can do to protect yourself. Naturally, it is all relative. It might be hard to lower your air pollution exposure to the level of someone living in an area with very clean air if you live in an area with very polluted air. And one’s financial situation can certainly affect one’s ability to lower air pollution exposure. But, through awareness everyone can do something.

Be Aware

The more you know the better decisions you can make. The amount of outdoor air pollution is complex, it depends on many factors, and will thus vary. If you know which days it is the worst, you can reduce your exposure by simply spending less time outdoors, avoiding outdoor exercise and perhaps keeping your windows closed, just as often recommended when there’s a fire nearby.

We recommend installing an app. Most governments around the world are measuring air pollution levels and sharing their results. There are many apps collecting this data and making it easily accessible for you.

I can highly recommend Air Quality | AirVisual from IQAir AG. It is available for both Android and iOS (iPhone). I have myself added a widget on my home screen, so that I’m made aware when the air quality is particularly bad. The widget shows the air quality based on my position by fetching the data from the nearest air quality monitor.

Figure 2. A widget on the home screen by the app Air Quality | AirVisual from IQAir AG. It shows the air quality from the nearest air quality monitoring station, based on my current position.

If you have an iPhone, your built in weather app is already showing the air quality.

As an example of how you can use air quality data to reduce your exposure to air pollution, consider figure 2, showing the air pollution levels in Shanghai the last 30 days.

Figure 3. A screenshot of IQAir’s data for Shanghai, showing air pollution the last 30 days. See https://www.iqair.com/us/china/shanghai for the latest data.

By being extra careful December 12th (the day with the highest amount of air pollution), you would have reduced your exposure quite noticeably. Just to illustrate, consider the following back-of-the-envelope estimates (based on the linear regression parameters found in [9] and performance IQ relation to PM2.5 increase found in [10]):

  • Not doing anything:
    Average PM2.5 exposure in 30 days: 38.43µg/m3
    Cigarette equivalent (total): 52.4 cigarettes
    Avoided Performance IQ drop compared to doing nothing: 0
  • Staying indoors 12th December in a room WITH air purifier:
    Average PM2.5 exposure in 30 days: 34.55µg/m3
    Cigarette equivalent (total): 47.12 cigarettes
    Avoided Performance IQ drop compared to doing nothing: 2.11
  • Staying indoors 10 - 13th December in a room WITH air purifier:
    Average PM2.5 exposure in 30 days: 29.12µg/m3
    Cigarette equivalent (total): 39.71 cigarettes
    Avoided Performance IQ drop compared to doing nothing: 5.08
  • Staying indoors 12th December in a room WITHOUT air purifier:
    Average PM2.5 exposure in 30 days: 37.01µg/m3
    Cigarette equivalent (total): 50.47 cigarettes
    Avoided Performance IQ drop compared to doing nothing: 0.77
  • Staying indoors 10 - 13th December in a room WITHOUT air purifier:
    Average PM2.5 exposure in 30 days: 36.19µg/m3
    Cigarette equivalent (total): 49.35 cigarettes
    Avoided Performance IQ drop compared to doing nothing: 1.22

Based on the above scenarios, if you have an air purifier (you might have a filter as part of your ventilation), by staying at home the single worst day, you could reduce your “cigarette” consumption by roughly 5 cigarettes in the 30 days. Or 13 cigarettes if you would stay indoors the 4 worst days. Even without an air purifier, you can make a difference for yourself and your family. Even one “cigarette” is one too much for a baby or pregnant woman, so any reduction in air pollution exposure does count.

Naturally, these are just rough estimates to give you an idea. In the above scenarios, we assume that you stay indoor the whole day(s), which is unlikely. Likewise, we assume that you are outdoors the whole time the other days, which is even more unlikely. So these estimates are just extremes. But even small reductions of air pollution exposure can add up in the long term.

Regarding the performance IQ drop, this is assuming that the pollution exposure would be the same in the long-term, for instance, you would avoid going out on days with particularly high pollution every month and roughly lower your air pollution exposure the same as in above scenarios. Furthermore, the study looked at the impact on teens, so unless you are a teen or have children, this is likely not relevant for you. We recommend you to read [10] to gain a better understanding of the relation between air pollution and performance IQ for teens.

We are also assuming that only the average air pollution exposure matters, where in reality short-term exposure to very high levels could be more harmful.

Even if we made many simplifications and unrealistic assumptions, the important point is that you can impact your air pollution exposure significantly over time by simply being a bit more careful on the worst days.

Indoor Air Pollution

Indoor air pollution is often overlooked by people. Global Action Plan’s survey [3] reveals that 32% believe it has no impact on their health, and 36% that it has a moderate or major impact. However, according to a WHO report [11], 4.3 million deaths were attributable to household air pollution.

It is reasonable to think that the household pollution comes mainly from outdoors. However, [12] looked at sources and found that in Copenhagen homes the majority of the ultrafine particles had indoor sources, in particular cooking and candles. The study compares the exposure to ultrafine particles in Beijing and Copenhagen homes: The residential daily integrated exposures in our study were higher than the results obtained from residencies both in California and Beijing. Unlike in Copenhagen, in Beijing the majority of the ultrafine particles came from outdoor sources.

Figure 4. 697µg/m3 in our flat in Berlin after searing beef. Outdoor air pollution was moderate (around 25µg/m3).

This shows the importance to be aware even if you live somewhere where the air is considered good. Some things to consider for reducing air pollution exposure indoors are:

  • Ensure your ventilation is working well, eg. by making sure supply and exhaust air vents are open and filters are clean or replaced according to maintenance guidelines.
  • Ensure that your kitchen hood is working and use it while cooking. Make sure to exchange the hood’s filter as specified in the manual. If your kitchen hood does not lead the air outdoors, there is typically yet a filter that must be exchanged, for example once or twice a year. Again, see your kitchen hood’s manual. Keeping your kitchen hood in good shape might be one of the most impactful things you can do to reduce your air pollution exposure.
  • Open a window when indoor air pollution is likely to be high. For instance, if you’ve done high temperature cooking (eg. fried bacon over high heat), lit candles or done any other indoor combustion / burning. Naturally, you might need to balance this with outdoor air pollution, but, keep in mind that several hundred of µg/m3 PM2.5 isn’t uncommon indoor when cooking (see fig. 4). So unless the air pollution is extreme outdoors, you most likely will benefit from opening your window for a bit.
  • Avoid indoor combustion, such as candles. Lighting a candle from time to time is unlikely to cause much harm, but if you have a habit of lighting candles every day, you might want to reconsider. In particular if you are pregnant or have babies at home. However, note that we are not aware of any official warning against candle usage.
  • Get an air quality monitor. This can help you to become aware of problems, and for instance tell you when you better open a window to get fresh air in, for instance to lower PM2.5 generated by cooking.
  • Get an air purifier. Ideally you should measure indoor pollution, for instance PM2.5, at several occasions first so that you both can say whether an air purifier is needed and whether it is working well. But, it is likely that a good air purifier would have a positive impact on your indoor air quality.

Outdoor Air Pollution

As mentioned earlier, getting an app, such as Air Quality | AirVisual, or using iOS built in weather apps, is a great way to become aware of when the air is particularly bad. You might then consider simply spending less time outdoors, or perhaps avoiding heavy outdoor exercise at least.

But for those keen to delve a bit deeper into this topic, Tim Smedley has written a very interesting article The toxic killers in our air too small to see [13]. It describes an experiment where pollutants were measured outdoors. An interesting finding is that the amount of cars passing by did not cause large variations in PM2.5. This is also in line with my own measurements (where I mainly saw large increases when in the vicinity of smokers). But, ultrafine particles varied significantly. These are tiny particles only expensive professional equipment can count.

Figure 5. Picture of pollen. The small particles making up PM2.5, or ultrafine particles, are significantly smaller and can’t be photographed.

The highest ultrafine particle counts were observed inside cars and buses (presumably non-electric). It is also mentioned that the distance from the source had a great impact on the particle count. An example is how taking a few steps from the kerbside to the building side of the pavement had a very noticeable impact on the particle count, but no impact on the PM2.5 measurement. It is important to note that unlike for PM2.5, there are as far as we know no set standards for ultrafine particles and the health impact of different amounts. But, it is mentioned in the article that the smaller particles are, the greater potential toxicity they have.

The article makes a case for how perhaps taking a walk through the park, in the forest or simply avoiding areas with heavy traffic can help you reduce your exposure to ultrafine particles. Remember, we learnt that just a few steps can lower the particle count significantly.

Even if the health implications of ultrafine particles are not known in detail (as far as we know), we believe it is safe to assume that fewer ultrafine particles is a good thing for both your and a baby’s health. And even if not, it is simply nicer to walk through a park or in a forest, compared to along a road with heavy traffic.

Don’t Worry But Reduce Exposure

We’d like to end with a call to not worry too much about this. As we learnt from Ella’s faith, awareness is important. But, we must still live, eat and go outside. In the end, it’s about reducing your exposure and opting for safer alternatives when you can. We hope that the next time things get smokey in your flat you remember to open a window. Or the next time you have the choice to take a detour through the park, you go for it. Many small things add up, and the more you know, the more likely are you to intuitively make good decisions for yourself and your family.

Naturally, if you have a respiratory disease, or worry about health implications of air pollution, we recommend you to reach out to your doctor or other official services offered where you live.


[1] “Ella kissi-debrah death: Air pollution recorded as cause of nine-year-old’s death in first ever case for uk,” Sky News, Dec. 2020, [Online]. Available: https://news.sky.com/story/ella-kissi-debrah-death-air-pollution-recorded-as-cause-of-nine-year-olds-death-in-first-ever-case-for-uk-12164155.

[2] “Ten health issues who will tackle this year.” World Health Organization, [Online]. Available: https://www.who.int/news-room/spotlight/ten-threats-to-global-health-in-2019.

[3] “Clean air public insight tracker press release march 2019,” Global Action Plan. Mar. 2019, [Online]. Available: https://www.globalactionplan.org.uk/news/clean-air-public-insight-tracker-press-release-march-2019.

[4] “Air pollution hurts the poorest most,” UN Environment. May 2019, [Online]. Available: https://www.unenvironment.org/news-and-stories/story/air-pollution-hurts-poorest-most.

[5] D. Carrington, “Revealed: Air pollution may be damaging ‘every organ in the body’,” The Guardian, May 2019, [Online]. Available: https://www.theguardian.com/environment/ng-interactive/2019/may/17/air-pollution-may-be-damaging-every-organ-and-cell-in-the-body-finds-global-review.

[6] N. Rees, “Danger in the air,” UNICEF South Asia. Jan. 2017, [Online]. Available: https://www.unicef.org/rosa/reports/danger-air.

[7] X.-Q. Jiang, X.-D. Mei, and D. Feng, “Air pollution and chronic airway diseases: What should people know and do?” Journal of thoracic disease, vol. 8, no. 1, pp. E31–E40, Jan. 2016, doi: 10.3978/j.issn.2072-1439.2015.11.50.

[8] R. A. Muller and E. A. Muller, “Air pollution and cigarette equivalence,” Berkeley Earth. [Online]. Available: http://berkeleyearth.org/archive/air-pollution-and-cigarette-equivalence/.

[9] G. Deng, Z. Li, and J. Gao, “Indoor/outdoor relationship of pm2.5 concentration in typical buildings with and without air cleaning in beijing,” Indoor and Built Environment, vol. 26, Sep. 2015, doi: 10.1177/1420326X15604349.

[10] C. A. Y. Wang Pan AND Tuvblad, “Socioeconomic disparities and sexual dimorphism in neurotoxic effects of ambient fine particles on youth iq: A longitudinal analysis,” PLOS ONE, vol. 12, no. 12, pp. 1–15, Dec. 2017, doi: 10.1371/journal.pone.0188731.

[11] “Burden of disease from household air pollution for 2012,” World Health Organization. Mar. 2014, [Online]. Available: https://www.who.int/phe/health_topics/outdoorair/databases/FINAL_HAP_AAP_BoD_24March2014.pdf.

[12] G. Bekö et al., “Ultrafine particles: Exposure and source apportionment in 56 danish homes,” Environmental Science & Technology, vol. 47, no. 18, pp. 10240–10248, Sep. 2013, doi: 10.1021/es402429h.

[13] T. Smedley, “The toxic killers in our air too small to see,” BBC, Nov. 2019, [Online]. Available: https://www.bbc.com/future/article/20191113-the-toxic-killers-in-our-air-too-small-to-see.