I want to measure my air pollution but I am a little bit confused what types of sensors should I order.
I want to measure PM2.5, PM10, O3, NO2, SO2,CO and C6H6.
This is a part of MQ 135 datasheet:
APPLICATION
They are used in air quality control equipments for buildings/offices, are suitable for detecting
of NH3,NOx, alcohol, Benzene, smoke,CO2 ,etc.
I read a lot of datasheet online but I was wondering if I can use MQ 135 for all these elements? So can I measure each element alone with MQ 135 or it gives me a response for all together?
AWOL:
Only if you can fit each with some sort of molecular filter.
Thank you for your response.
So what do you suggest me to do cause I need to measure those elements.
It seems complicated with molecular filters Do you think is better to use other types of sensors for each element?
For example I have searched that: C6H6 can be measure by HCHO Sensor and NO2 by MICS-2714.
But when i read the MQ 135 datasheet i thought I could use it for C6H6 and for NO2.
AWOL:
You can use it to detect them, but it can't distinguish the concentrations of each.
If this isn't a problem for you, no worries.
No I really need to know the concentration of each so I am going to use specific sensors for each element not MQ-135. So if I use the sensors that i mentioned above will my project work good ?
Klajdi:
I want to measure my air pollution but I am a little bit confused what types of sensors should I order.
People in Beijing, China, which is one of the world cities with heavily polluted air, typically just measure just one value: fine particles in the air:
This is currently one of the best selling products in China (already sold: 360 million units): The Laser Egg
Nearly every household in Beijing and many people in China already posess one.
It shows just one number for "fine particles in µg/m³" and a short statement about whether this is healthy or not.
The Laser Egg is currently one of Chinas best selling products. The measurement is fast reacting, so you can see fast changes in particle concentration from walking out of your room (perhaps with filtered air) to the balcony with heavily polluted air like in Beijing. I think this is the promotional video on Youtube:
And I think that "fine particles in µg/m³" is a very good parameter for monitoring air quality: Car traffic is creating ultra-fine particles as well as industrial productions and house heating systems. So this single value will tell you a lot about how polluted the air is at the moment.
So if you want to measure good results from just one sensor, chose a "ultra-fine particle sensor" or a "dust sensor"!
The MQ sensors are great to let you know if there is pollution. They give a simple output that is easily read.
It you want to measure pollution then they are crap. To measure that set of parameters with reasonable accuracy and high specificity then you are looking at thousands of dollars.
it is simple math. a cheap sensor will not offer individual gas sensing.
specific gas sensing will require special 'specific gas' sensors. these can be vastly more $$$$
I used to use a 'wet' gas sensor. these had a volume of fluid that contained some specif liquid. that liquid was compared to the desired gas to be sensed. the ones I used for CO, carbon monoxide in underground parking garages, would use up the liquid in proportion to the amount of CO in the air. some lasted for years, some for months.
At this point, you do not come accross as an expert, but if you were very well versed and had great programming skills, you could use multiple sensors. if sensors 4 and 7 both could read H2So4 and each did read other things that were not overlapping, then you could assume that if both sensors when high, and since only H2So4 would effect both, then H2so4 was present... this a horrible scheme and not one I would recommend.
there are at least 3 manufacturers of sensors that we typicaly use are Figaro (most are not aware of them) http://www.hwsensor.com/ these people make the cheap ones we mostly use.
I don't have the 3rd one here at work......
jurs:
The Laser Egg is currently one of Chinas best selling products.
Thank you but the idea of this project is to make itself not to buy a gadget
MorganS:
To measure that set of parameters with reasonable accuracy and high specificity then you are looking at thousands of dollars.
I do not really want to spend thousands of dollars cause I am a student and I just wanna do this project for fun. But I have found some types of sensors for each element which I want to measure.
For example:
1- CO with MQ 309 A
2- O3 with MQ 131
3- NO2 with MICS-2714
4- SO2 with MQ 136
5- C6H6 with Grove HCHO sensor
Those sensors are typical for each element so I think it should work but I wanted your opinion just in case you have tried before
Klajdi:
Thank you but the idea of this project is to make itself not to buy a gadget
What about this sensor then:
Sensitivity is: 0.5V/0.1mg/m3.
That is 0.5V output at 100µg/m3 fine particles.
As typical fine particles should be less than 32µg/m3 average in non-polluted air, you most likely will want to use a lower measuring range than the Arduino default range (analogRead() DEFAULT 5V), but depending on the board you possibly can use analogReference() to create a more sensitive measuring range, i.e. "UNO" and "INTERNAL" reference = range 0..1023 = 0...1.1V.
In the USA, for example, particle concentration is officially published, as maps for forecase and current values: http://www.airnow.gov/
They just convert the particle concentration into an AQI (Air Quality Index) by the fine particles measured in µg/m3:
Good = <50
Moderate = 51...100
USG = 101...150 (Unhealthy for Sensitive Groups)
Unhealthy = 151...200
Very Unhealthy = 201...300
Hazardous = 301...500
Action Day = >500
On an Action Day there will take place official actions in some US Cities, but I don't know about that (I'm German) http://www.airnow.gov/index.cfm?action=airnow.actiondays
BTW: Here in Germany, the fine particle concentration in houses is very often higher than outside. Hard to believe for people, that the air pollution in their "clean house" is higher than near a road, where the cars drive by. But there are many sources of fine particles in every house, and not only in houses where smokers live.
simple advise is to start.
all work is a learning process and each step is one more towards your goal.
no one jumped in and said it cannot work, and we are frightfully good at sharing our disasters.
my only caution is to get a large enough power supply and keep notes on the sensors.
in my searching, figaro was the most expensive, but the lowest power for all the 'heated element' styles.
AirWick has a sensor that is a MEMS sensor that runs off, I think an AA battery, but I was not able to source that chip. and it appears that AirWick is not in major production. guessing, it was either too hard to manufacture, or no one wanted to buy the product.
Do you think is better to use other types of sensors for each element?