Sunday, 26 March 2017

Pollution (PM2.5), Negative Ions and a look at how effective ions are at reducing PM2.5 levels.

I live in shanghai and the air isn't always great. This has caused me to take great interest in methods to ensure the air quality in my home is high. Today I will focus on the effects that negative ions have on PM2.5 levels.

PM2.5 levels refer to the amount of particles floating around in the air smaller than 2.5 microns. A human hair is roughly 70 microns thick.

Instead of talking about published research I will rather do my own experiments today, and give the results as best I can along with pictures. I intend to test just how effective negative ions are at reducing PM2.5 levels. I have now numerous times come across unfounded articles that say only HEPA filtration devices can remove PM2.5. I know this is not true, and will demonstrate it today.

I will conduct 3 separate tests according to the following.


I have a smallish balcony, about 4m x 2m giving me about 8 square meters (90 Square feet) and 24 cubic meters (847 Cubic Feet) of air. One side of the balcony is closed off with sliding doors leading into the apartment, and the other with sliding windows that can either be opened or closed depending on weather. The sliding windows unfortunately do not give a good seal, and we will have both inside air going out, and outside air coming in.

Air Conditions

According to two sources, the air quality in Shanghai 27 March 2017 is 128 ug/m3 on the Iphone weather APP and 177 ug/m3 according the the AirPocalypse APP.  My personal reading prior to starting tests of the air quality on the balcony with windows open was 87 ug/m3. We don't live in the city center.

This means with the sliding windows that don't seal properly, we will have the outside air affecting lower PM2.5 levels.


The air quality of outside air due to the windows not having a good seal does affect the lower readings. We have air with PM2.5 levels over 100 ug/m3 continuously entering the testing area which will affect how low the reading can go. Had we had a perfect seal, the readings could go lower for both test 2 and 3. The opposite is true for test 1. The second hand smoke would have stayed in higher levels for longer.

Test 1: 10:30
Test 2: 09:00
Test 3: 07:30


The PM2.5 meter that I will be using gives PM2.5 and PM10 readings, either a single reading, or a continuous reading in the form of a chart. It is a Chinese name brand, was relatively inexpensive (100 Dollars) but seems to give very accurate readings.

The Negative Ion Generator is a NaturAir Twin Air Pro Negative Ion Generator. This specific ionizer was one of my prototypes. It was manufactured in June 2016 and has been running 24/7 in my home since then. It's 9 months old, and still produces negative ions in the trillions. It is exactly as effective as it was the first day I started using it.


1. Will light a cigarette and leave it to burn out. I will then take a PM2.5 reading after 10 mins, 30 mins and 60 mins. The Negative Ion Generator will remain switched off so we can see the natural drop off based on the testing setting, conditions and interference.

2.Will light a cigarette and leave it to burn out. I will then switch on a powerful Negative Ion Generator after 10 mins. I will take a PM2.5 reading after 10 mins, 30 mins and 60 mins.

3. The Negative Ion Generator will be switched on 30 mins before lighting the sigarette. I will allow the PM2.5 meter to take continuous readings of the air quality for up to an hour. I will note readings after 10 mins, 30 mins and 60 mins.

PM2.5 levels were checked and found to be stable at around 85-88 ug/m3 prior to test 1 and 2. Windows were open. Test 3 had windows closed to allow ion concentration to build up with PM2.5 levels at the start of the test being 38.9 ug/m3.

Final word prior to testing

I believe the 3 different experiments will show how negative ions affect PM2.5 levels to a reasonable degree.

The reason I use a sigarette is because 1 sigarette and the smoke it produces leaves the PM2.5 levels at over 999 ug/m3. My meter maxes out at 999 ug/m3 so we cannot know today just how bad smoking (Second hand smoke for family and friends) really is for our health. All smokers please pay careful attention to the air quality you are introducing into your home if you do smoke inside.

The table below and the cautionary statements should be an eye opener for anyone who smokes indoors. Levels above 300 ug/m3 but still below 500 ug/m3 have serious warnings associated with them and is classed as HAZARDOUS. 1 cigarette in a non-ventilated non-ionized area pushed levels well above 999 ug/m3.

PM2.5 levels and what they mean:

 Air Quality Index (AQI)  PM2.5 Health Effects Statement Cautionary Statement

 PM2.5 air pollution poses little or no risk.


Unusually sensitive individuals may experience respiratory symptoms. 
Unusually sensitive people should consider limiting prolonged outdoor exertion.

Unhealthy for Sensitive Groups(101-150)
Increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly.   Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

 Increased aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; increased respiratory effects in general population.Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.

Very Unhealthy
 Significant aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; significant increase in respiratory effects in general population.Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.

 Serious aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; serious risk of respiratory effects in general population. Everyone should avoid all outdoor exertion.


Test 1

During this test, no negative ions were introduced with windows open prior to test. After 10 mins the PM2.5 levels were 999 ug/m3. After 20 mins the PM2.5 levels naturally faded to 316.8 ug/m3 and after 60 mins the residual PM2.5 levels were 171.7 ug/m3.

During the test, around the 30 minute mark there is a significant drop off in PM2.5 levels. I am not sure if my opening the door to go and take the picture allowed a great deal of bad air to escape, of if there was a pick up in wind activity. As per the graph we can see the PM2.5 levels drop suddenly, then stay around the same level with only small drops being noted during the last 20 minutes.

Test 2

The Ionizer is not switched on for the first 10 minutes of readings. Over the period of 10 minutes we can see the PM2.5 levels climb to 999 ug/m3 (max reading of my meter). At the 10 minutes mark, I switch the Negative ion generator on. Reading at 10 mins is 999 ug/m3. After 30 mins (20 mins with ionizer running) the PM2.5 reading was 372.2 ug/m3 and after 60 mins the levels were down to 105.9 ug/m3. We can see a gradual and consistent drop in PM2.5 levels.

Test 3

With the area already filled with negative ions we can see a huge difference into the PM2.5 levels caused by smoke. The smoke and harmful particles are removed very quickly never allowing the PM2.5 levels to reach 999 ug/m3 or higher. Within 30 minutes the smell of smoke was no longer apparent with PM2.5 levels at 51.5 ug/m3. After 60 mins the PM2.5 levels were at 43.4 ug/m3. 

Table for comparison

Color coding for this table is different from the Air Quality Index (AQI) table due to the AQI table maxing out at 500 ug/m3.

 Reading after 10 minutes Reading after 30 mins Reading after 1 hour
 Test 1 - No Negative Ions 999 ug/m3 316.8 ug/m3171 ug/m3 
 Test 2 - Negative ions after 10 mins 999 ug/m3 372.2 ug/m3105.9 ug/m3 
 Test 3 - Negative ions 30 mins before 595.6 ug/m351.5 ug/m343.4 ug.m3 


The results clearly show that an area full of negative ions prevent PM2.5 levels from building up, and in turn has the levels or harmful particles in the air drop a lot quicker than without the negative ions present.

Test 1 we see after 15-20 mins there is a drastic drop in the PM2.5 levels. We are not sure exactly what caused this (gust of wind could be the culprit), and will rerun this part of the experiment at one point to see what the actual natural drop off is. The main figure to look at is the measurement after an hour and compare that to the measurement of Test 3 when Negative ions were present prior to the experiment starting and having had time to build up.

Test 2 we can see that by the 30 min mark the negative ions had not had enough time to really bind to, and drag down the particles in the air. The ionizer was switched on after PM2.5 levels were already high and needed time to be able to build up and go to work. The reading after 60 mins and if we look at the continuous reading shows a steady decline path. Already the air was much cleaner than without the ionizer present.

' By causing allergens such as pollen, mold spores, dust, and animal dander floating in the air (which have either a neutral or a positive charge) to be attracted to and stick to each other, forming 'clumps' (because opposite charges attract). These clumps of particles then become heavy enough so that gravity can pull them down to the floor, where they can be vacuumed up, rather than staying in suspension'

Negative ions need time to build up, and in bad quality air, take a little longer to build up to the required levels to remove particles floating about in the air.

Test 3 show clearly that once the ions have had time to build up, the difference they make to air quality is quite noticeable. The concentration of negative ions in the air was already very high, allowing them to quickly bind to and drag down particles floating around in the air.

These results would indicate the any articles claiming that only HEPA filters can remove/lower PM2.5 levels are wrong. Negative ions do an amazing job of removing PM2.5 levels quickly and lowering them to a level considered safe.

Negative ions aid our health in ways documented many times over. They are as effective at removing PM2.5 as HEPA filters and have the additional benefit of aiding our health more than just the clean air a product reliant on filters can do.

As always, the ionizer used in the testing today can be found here:


  1. This is fantastic information!!!! Amazing how we are told that second hand smoke is hazardous, then not. A smoke filled room is bad news. This lends creedence to your leaving the negative ion generator on 24-7. TRhanks for your information here, I will be sending this blog entry to many friends.

  2. Great article here, very interesting to note the 50% reduction when there was an abundance of negative ions. Even better to see the air quailty drop below 80 to 43. This just shows how the air quality can be improved with the naturair negative ion generator. As someone who has a naturair pro, i can personally atest to the evident benefits, less dust on surfaces, fresh air feeling in the room, less odours. Fantastic!


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