5 Simple Steps to Running a Formaldehyde Cookout

Newly renovated apartments and offices typically have high levels of formaldehyde. One of the most effective ways of removing formaldehyde is to run a formaldehyde cookout. But what is a formaldehyde cookout and how do you run one? In this article, we show how to run a cookout in your …

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Do Air Purifiers Dry Out the Air?

Empirical data shows that air purifiers are great at cleaning air, but do they dry out the air and lead to other health problems? For me, dry air is mostly just a comfort issue. But for some people, dry air can exacerbate health problems like allergies and bronchitis. Do HEPA …

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India Delhi Indoor Air Quality vs Outdoors

Delhi’s Indoor Air Pollution Lower than Outdoors

Whether indoor air is safer than outdoor air is an important question for the millions of people living in heavily polluted cities like Delhi or Bangalore. Yet I’ve heard a lot of disagreement about this question. Is indoor air really safer than outdoor air? Is it true for all areas …

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Smart Air Indoor Air Quality Audit in 3ESpace

Date of audit: 27/05/2017
Audit conducted by: Yap Choon Khin

Paddy Robertson

Air quality monitor: Dyloc DC1700 Pro

AirVisual Node

Audit location: 3ESPACE, Beijing Jiaodaokou, Xinhua New Culture Building, 5th floor
Air quality measurement outside premises: 115 µg/m3
Corresponding Air Quality Index (outdoors)[1]: 182
Air quality inside premises: 70 µg/m3
Corresponding Air Quality Index (indoors): 158


Outside air pollution

Smart Air visited the 3ESpace co-working space on 27th May 2017. We used a Dylos DC1700 to measure the outdoor air quality along the front and sides of the 3ESpace building.

The average outdoor PM2.5 concentration was 115 µg/m3, which equates to an Air Quality Index (AQI) of 1821. This AQI level corresponds to an ‘Unhealthy’ air quality level.

We then made visual inspections of the surroundings and found the following possible sources of local pollution which could affect 3ESpace’s indoor air quality:

  1. Pollution from the busy road in front;
  2. VOC and large dust from the construction works behind the building;
  3. VOCs and PM2.5 from smokers outside the building main entrance.

However, we also noted that the 3ESpace building is generally surrounded by houses, which are unlikely to produce large sources of pollution.


Inside air

We tested the indoor air quality in 6 of the 3ESpace rooms, and the average indoor PM2.5 concentration was measured as 70 µg/m3. The corresponding AQI is 158 (US), which coincides with an air quality level of ‘Unhealthy’.

Using the AirVisual Node, we measured indoor CO­2 levels, and found the average to be 578 (a typical outdoor CO2 reading is around 400-600). From this, we can conclude that the premise is well ventilated and there is unlikely to be a large build up of VOCs or other gases inside.

Inside, we used the Dylos DC1700 device to check for leaks around windows. The windows are well-sealed with a low risk of them leaking PM2.5 into the building. However, the windows were open in one of the small incubators and rooms. Having windows open when purifiers are running drastically reduces their effectiveness at removing air pollution.

See Figure 3 and Table 3 in Appendix 1 for more detailed results on the indoor air quality tests we performed.

Purifier habits

6 Xiaomi purifiers had been installed by the 3ESpace staff on the premises 5 months ago. Unfortunately, during the time of our inspection, only one of the purifiers was turned on. The Xiaomi in question was in its ‘auto’ mode, which we’ve previously tested and found to be extremely ineffective.

We discussed purifier operation habits with the 3ESpace staff, and found that purifiers were only turned on when the pollution ‘looks bad’. Furthermore, some of the staff did not believe that air purifiers do anything to reduce air pollution. It is important that all the staff understand the benefits and importance of having an air purifier indoors, and turning it on whenever the AQI reaches ‘unhealthy’ levels.


The Cannon

Using the Smart Air Cannon purifier, we performed a simple 30 minute test in one of the 19m2 meeting rooms. During this test, the Cannon reduced the room’s PM2.5 concentration from 71µg/m3 to 23µg/m3, a reduction of almost 70% in just a 30 minute period.

Figure 1: PM2.5 levels when testing the Cannon

We recommend that affordable yet effective air purifiers like the Cannon be used to lower indoor PM2.5 levels.


We were surprised to find that although 3ESpace had 6 purifiers installed, not all of them were turned on. We highly suggest that existing purifiers be turned on when the outdoor AQI level is above 100.  For the larger rooms, small household purifiers like the Xiaomi would not be adequate to clean the entire space. Therefore, we suggest 3ESpace install larger industrial units like the Smart Air Blast purifiers in these rooms.

Below are room-by-room suggestions for purifier installation:

Room Action needed
R1 Turn on 2 Xiaomi purifiers when required
R2 Install Smart Air Blast purifiers
R3 Install Smart Air Blast purifiers
R4 Turn on 1 Xiaomi purifier when required
R5 Turn on 2 Xiaomi purifiers when required
R6 Turn on 1 Xiaomi purifier when required

Table 1: Recommended action for rooms visited


We recommended that all staff attend a Smart Air workshop, a great way of educating them on to the air pollution situation in Beijing and how they can protect themselves from air pollution.

It is also important that 3ESpace delegate one person to oversee the purifier operation in the entire co-working space. He/she is recommended to check the AQI twice a day and turn on ALL purifiers and close windows whenever the AQI level increases above 100.


Next Steps

We hope that with our analysis and recommendations, 3ESpace will be able to breathe in more clean air. For any queries or discussions regarding the audit, we are contactable via email ([email protected]).


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How Much Pollution Do We Breathe Every Day?

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Car Air Pollution Stopped Driving

Do We Need Car Air Purifiers? Do they Work?

Car air purifiers sound like a great idea. But do we need them? Do car air purifiers even work?  Soon after I started making DIYs, people emailed me asking if we could make an air purifier for their car. My initial reaction was, “Great idea!” On the highways, we’re surrounded …

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How Safe Is Indoor Air?

I recently did some research on whether indoor air is as bad as outdoor air. Before that, I had a conversation with a friend in Beijing that went something like this:

Friend: I’m not sure if I can make badminton tomorrow. I have a basketball game in the day.

Me: Oh man, do you play outside?

Friend: Nah, it’s inside.

Me: Oh, phew. Good.

Friend: Wait, why do you say that?

Me: Oh, the air is way worse outside. I used to feel like I had asthma after playing basketball outside.

Friend: Really? No, they’re not that much different. I saw it’s just 20% different.


Seeing as how nerds cannot let matters of fact go, I started using my particle counter to take measurements of inside and outside air at different locations around Beijing. This answer is important: it tells you if it’s any safer to exercise indoors and how much damage you’re doing to your lungs by choosing that seat outdoors at your favorite cafe or restaurant.


The Test

So I took measurements in six locations around Beijing, in apartments, cafes, and my gym. I only chose bad days (pollution concentration above the WHO standard of 25), and I avoided days where it rained (because rain can cause quick changes in air quality). Here’s what I found:


On average, indoor air had only 36% of the pollution outdoors.


Things were a little worse for the smaller .5 micron particles, but still much better than outside:


On average, indoor air had only 51% of the .5 micron particulates of outside air. My guess is that the .5 micron data was worse than 2.5 micron data because it’s easier for smaller particles to get into your home and stay suspended in the air.

There is a lot of variation between places. For the 2.5 micron particles, the locations varied from 14% to 58%. Dr. Saint Cyr also found significant variation between two apartments he lived in, 50% to 70%.


Conclusion: Indoor air is relatively safer

In terms of particulate pollution, you’re safer snagging an indoor seat and working out indoors, particularly on bad days (I’ve seen some argue that we are particularly vulnerable when we work out because we breathe more deeply than normal).

But remember that doesn’t mean indoor air is safe, just better than outside. For example, if your air at home had 40% of Beijing’s concentration last night at 11pm (8/15), you would’ve had 64 g/m3 in your home, which is more than twice the WHO standard of 25.


As usual, I’m posting more on my methods and raw data below.


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Smart Air is a social enterprise that creates simple, no-nonsense air purifiers and provides free education to protect people’s health from the effects of air pollution. We are proud to be the only certified B-Corp dedicated to fighting air pollution.