Indoor Air Quality – Home Test Kits – Hydrogen Sulphide(H2S) & VOC’s

H2S home test kit.

A very simple to use test kit, for you to use in the home. The equipment is deployed in your home and is allowed to sit and take in gases for diffusion, for between 2 and 4 weeks.

After which time it is sent to the laboratory where it is analysed for hydrogen sulphide. The lod ( limit of detection is of the order of the low parts per billion)

H2S Has an unpleasant “rotten egg” smell, usually when the concentration is at or above the 5 micrograms/m3. The WHO (World Health Organisation) Sets a limit of 7micrograms /m3 as a 30min average. Above this level authorities would expect to receive significant complaints


Can cause :

  • eye irritation
  • headaches
  • Nausea

The lowest adverse effect of H2S as reported by the WHO, tends to occur in concentrations above 15mg/m3 ( around) 10 ppm)

For further information of tube monitoring and new real time remote monitoring products, please contact



Would you trust an indoor air quality tech site ?

ArmiteMini iaq
Airmite Mini
indoor air monitor from EM-monitors

Tech sites which refer to indoor air quality (iaq), draw us into is an emotional argument. These reports tell us of  dangerous pollutants that surround us. Which can cause us serious harm. This  is why we need the ….”Z box”

The “Z box ” will measure 8 zillion components all to within the accuracy of a nats breath.

Which is real terms means ……absolutely nothing

No one ever brings up a WHO standard. Or even mentions calibration, testing or accuracy.

Recently i came up across a client who had purchased a HEPA ( High Efficiency Particulate Air Filter) combined with a charcoal filter in order to provide workers in the office space with confidence that the air was clean and filtered.

There are a number of issues with this. Whilst some HEPA filters are good many operate on the edge of being useful to achieve this level of particle size removal. Typically a HEPA system operates at 0.3micron , a corona virus size is of the order of 0.1micron (100nm). However when the virus associated with an aerosol the filter can provide some useful reduction of the aerosol with associated. Independent assessment of these systems in vital to their correct use


We would not buy children’s medicine from the chap in the market, who has no credentials, however its perfectly reasonable to make random internet purchases on goods which are supposed to be good for our health.

note references made are always about “style”, “size” “looks” and “features” but not a jot about how it is tested and whether it really works!



accurate indoor air quality


Indoor Air Quality Assesment

When monitoring indoor air quality (IAQ), it is important before we pick up any piece of monitoring equipment, that we have a method and protocol to tell us what we are monitoring, how and where we sample and with what equipment.

There are a number of good iaq guides which have devolved from ASHRAE, there are also indoor air quality specification with part F of the building regulations

We recommend as a basic monitoring scheme that the following would be need to be monitored,

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indoor air quality em-monitors
indoor air monitor

Item                        units                        range

  • Carbon Dioxide       ppm level                  0-5000
  • Carbon Monoxide   ppm level                  0-500
  • Relative Humidity    %                               0-95%
  • Temperature            Deg C                        0-50 Deg C

A good quality, professional grade monitor for this typically costs around £1800 to purchase or

Real time data logged using accredited devices

additional monitoring may be :

  • VOC’s- Total voc’s at ppb level
  • specific voc’s  – Formaldehyde

Particulate and fine particulate

real time dust monitor
Dust monitor
  • pm10
  • pm2.5
  • possibly ultrafine particulate (nano particulates)

depending on the type of room being monitored, it is also important to consider

  • Airflow – along the floor area, around the head area
  • microbio sampling for different bacteria  Aspergillus, Cladosporium, Penicillium

other considerations

  • light
  • decor
  • noise and vibration

Multiparameter monitor:

real time dust and NO2
Dust and NO2

PM10, 2.5. 1

Relative Humidity


NO2 ppb

please click on the specification below

Airmite Mini Spec 2021



01539 727878






Indoor Air Quality Monitoring – using low cost sensor and standard methods

As people return to work after covid lock-down, many were concerned as to how clean their office was. They deployed many types of monitoring methods.

For a number of organisations this meant, operating in a field that they new little about and purchasing equipment on line that was neither suitable for the application, had no validation(Mcerts)  or calibration.  They had no knowledge on a reporting standard that they required to meet, nor what that would mean

Other groups of people are seeking to get a certification for their building, such as Breeam, Well, LEED

When perform Indoor Air Quality(IAQ) we can define a number of key pollutants that we can monitor. These include:

NO2- Nitrogen Dioxide

PM10, PM2.5- These are particulate matter (PM) with a size of , either less than 10 microns (PM10) or less than 2,5 microns

CO2 -Carbon Dioxide

CO, carbon Monoxide

Temperature and relative humidity (RH)

Formaldehyde – This is a basic set of monitoring that can be done within a building.

Of equal importance is : What are the sources of these pollutants and how do we mitigate for them.

Where do we sample from ( our sampling location ) and for  how long and at what rate?

What do are results mean and what do we compare them with . can provide monitoring equipment that is accredited – provides consultancy to monitor for these

ArmiteMini H2S
Airmite Mini H2S from EM-monitors

New Hydrogen Sulphide PPB Monitor

Traditional the most accurate way to monitor for hydrogen sulphide was using the Arizona Instruments Gold Leaf Monitor or the Honeywell SPM toxic gas detector. Today this is still true, these techniques are still the most accurate. However other technologies are gaining ground.

The newer technologies have the advantages of being:

a, Continuous

b, Affordable

c, Remotely monitoring to a data dashboard with csv file download

We now Supply our Airmite mini H2S with

real time monitoring of H2S at the ppb level (range 5ppb to 20 pmm).  it also measures:

real time pm10, pm2.5 and pm1

real time Humidity and temperature

GPS location and 4G remote connectivity or ethernet cable connectivity

This is instrument is ideal for waste water treatment, odour monitoring, or nuisance monitoring of hydrogen sulphide odour

ArmiteMini H2S
Airmite Mini H2S from EM-monitors

The Insanity Of “Tech Reviews” Regarding Home Air Monitoring Products

There was a time when reviews of products actually meant something . We are all too familiar with journals and magazines promoting products that their magazine had the manufacturer as their main advertiser or sponsor. A classic example of this is hifi magazines.

Not good , not fair, however at least people writing the article had a good knowledge of the product and a deep seated interest.

Where we used to apply BS kite marked standards  to products, now it is a free for all.

With regards to Air Quality Monitoring, new low cost sensors mean that the technology suddenly becomes affordable. Cheap is one thing but reporting accurately is another.

Normally when a product is built, it is designed to meet a standard. In this case an air quality or indoor air quality standard. However we don;t have an indoor air quality standard for homes or buildings. The BS ambient atmospheres is working towards a standard but it is slow  whilst chaos around them ensues. The nearest thing we have is a mixture of part F of the building regulations looking at NO2, CO and TVOC

And now here is the rub. So in all of the reviews – no one – yes – NO ONE performs any validation testing. Either against a reference standard test gas or a secondary standard monitor.

One chap reported that ” the temperature was 6 degrees out, but other than that it worked fine” !!!! A 8 year old school could good make a device with an accuracy to 0.1 degree. So the guy was happy measuring the device against something he though might be accurate. But was clueless in understanding if :

c;lean air monitring
Air quality
Airmite mini Dust plus 1 gas
compact remote dust & gas monitor

indoor air quality

b, what a correct reading would be anyway


For the record i am adding some guideline values here. This is difficult to source as many organisations and countries use different reporting criteris > ie 15mins , 1 hour , 8 hours etc

NO2 150ppb – 8 hour average

CO- 90ppm      15m average

CO 10ppm        8 hour average

TVOC  300ug/m3 8 hour average

O3    100ug/m3

CO2 – 400 -1400 8 hour average

occupation limits suggest 5000 ppm  as 8 hour average

one thing we can offer is to validate your monitor against a calibrated standard





Monitoring Office Air – New Building Air Quality Monitoring Confusion

Technology is moving on in leaps and bounds. We are now able to switch on our home TV on whilst traveling in our car. All so that Twicki your pet hamster can watch Brooklyn 911.

We are now capable of building an array of sensors that can measure all manor things. These sensors are now being fully integrated into our home and work place. From heater controls, HVAC controls, security cameras and much more in the intelligent building.

The field of Indoor Air Quality Monitoring has become a real eye opener. Where does this requirement come form ? Many of the Millenials want instant data, acquired to a phone App. Instant gratification. Knowing what the air in the room you are in consists of

The other drivers are things like BREEAM, WELL and LEED. These certification schemes afford credits to buildings that are built with the ability not only to minimise the amount of hydrocarbon in the building but also to monitor total hydrocarbons and other parameters such as fine particulate (pm2.5 – fine particulate has a diameter of less than 2.5micron, which means it is respirable). Other items include:

Nitrogen Dioxide (NO2)

Total Volatile Organic Compound (TVOC)

Carbon Dioxide (CO2)

Carbon Monoxide (CO0

Relative Humidity (RH)

Temperature (T)


The huge issue here is that there are no standards or certification for Indoor Air Quality Monitors. Most companies purchase an unvalidated products to put in their “Smart Building” These are simply not viable. Most of this type of product is garbage purchased on line.

To put a simple perspective on it, if you felt unwell you would go to a doctor, you wouldn’t go to Asda and ask the person in groceries to provide help? They would sell you an apple!

So why would you do it for incredibly specialised equipment.

Airmite Em-monitors
Airmite Smart monitr

A recent study identified shortfalls in the mass market air quality sensors

Formaldehyde and Total VOC (TVOC) Commercial Low-Cost Monitoring Devices: From an Evaluation in Controlled Conditions to a Use Case Application in a Real Buildingby

It states the response of the sensors was in many cases a lot lower than required , linearity was poor as was repeatability and reliability. For example Formaldehyde is a very specific hydrocarbon. There are specific iso methods as to how it is monitored. To identify it amongst a range of other hydrocarbons using low cost sensors may be duplicitous

There are new sensor which, are primarily used for the air quality market but also good for the indoor air quality market.

Environmental Monitoring www, and have spent a long time looking at these issue. Working with partners at the HSE and SCS. We now have Mcerts Accredited air quality monitors. As well as an accreditation, they have been co located and type tested again Government run reference monitoring systems ( reference systems cost in the region of £100, 000)

Good  professional install air quality monitors cost between £3,000 and £6,000 . They are accurate and precise.

However these units have to be carefully installed, at the correct height, with power and the data must be managed. Not only the data but the servicing and validation of the equipment.

For information of types of monitor and



Airmite mini Dust plus 1 gas
Airmite Mini Smart compact remote dust and gas monitor




Air Tight Building Issues

em-monitors pid years ago Environmental Monitoring were asked to review the air quality within a new building just of the north circular in London. We went in with a blank sheet. No pre-conceptions of the how the house was constructed.

The owner had purchased the house for several million pounds but felt that it was not possible to occupy the house because there was and i quote “no air” in the house.

As part of the local authority building requirements, the building had to be designed to not only be airtight but also to have an active filtration system.

We provided the client with a full suite of monitoring equipment for hire including

Indoor air quality monitoring for :

Carbon Monoxide

Carbon Dioxide


Relative Humidity

Ambient Pressure

TVOC ( total volatile organic monitoring)

Particulate  aerosol sampling

Microbio sampling

Airflow monitoring

We also provided an independent review of the premises .

What was discovered –

Carbon Dioxide CO2 readings were typically around the 1500-1800ppm range

Relative humidity was 68-69%

Air flow was negligible

Ambient temperature was in the range of 23-25 , without any heating operating

internal ambient pressure was greater then external ambient.

Upon closer investigation, when we reviewed the filtration and air distribution system. The manual from the manufacturer stated that the ducting should be smooth bore rigid tubing. However the electricians that fitted the system used corrugated, flexible tubing. Upon removal it was found to be loaded with mould. The perfect distribution system.

To summarise . In trying to solve one problem. That of heat loss and heat inefficiency, it appears other problems have been created. Mould appeared in rooms without any explanation.

There were many problems, exacerbated by a poorly installed and not understood air filtration/ distribution system

Giving rise to :

  1. Poor Air Flow
  2. High Relative Humdity
  3. Mould Growth

The equipment used was a mixture of real time calibrated indoor air quality monitors . All the equipment was of a professional standard. Calibrated prior to the test it included :


Mini RAe 300 pid

Dusttrak DRX

MB2 Microbio sampler

Druck 750 pressure monitor

Kimo-instruments air flow

all supplied by Environmental Monitors it is important to note that modern home monitors tend to under report many of these issues. Each of our instruments cost several thousands of pounds and are regularly calibrated. That said we good observation and fresh air “rinsing” you can build a reasonable picture of your home environment using a cheap device

Smart Air Quality Monitors- We are moving in the right direction but..

We currently live in a world where we are able to access a myriad of facts, all a button click away on our phones.

We then enter beautifully manicured websites promising us a utopic world where everything can be monitored and then be directly read to an app on your phone.

The good new is we are getting cost effective monitors that we can carry around with us or use in the home but…. what are they reading.

I have spent most of my life working in air monitoring. In order for a product to give you some information that you can look at and trust you need to have a set of rules to to help define what it is you are looking at.


For example when you buy 5 kg of potatoes in a sealed bag – you either trust your getting five kg or you don’t care you just want spuds. The 5kg comes from the fact that the potatoes have been weighed. We know the weight is correct because at some point in the day, or week a calibration weight of 5kg is placed on the scale where they are packed and the scales are adjusted to be accurate.

This applies to any measurement we take. The thermometer at your doctors, or the speed camera used by the police.

Many indicative monitors don’t have this, though some do

Professional Reference Monitoring equipment would typically cost around £100,00.00. it would use reference monitoring techniques. However it would be used as follows:

So as you see it is all quite complex. lots of checks.

Moving down below reference equipment is cell technology. It is small and compact. it is what we are seeing out on the street now and in a myriad of pretty boxes for the home. Some of these are accredited and some also have very serious algorithms to correct their functionality. These are professional use tools and cost £3,000 upwards.These are Indicative Monitors. There are also more basic home use indicative monitors

Indicative Monitors

But be careful, many of the Chinese imported products are simply garbage and will respond to anything.

What do most of the Indoor Air Quality Monitors Do well?

  • Relative Humidity (%RH)
  • Temperature
  • Air Presure
  • Carbon Dioxide

Areas where they tend to perform poorly

  • VOC’s most commercial voc monitors require regular and careful calibration, VOC’s can include anything from Formaldyde , to perfumes & deoudorant
  • Nitrogen Dioxide (NO2) – product of combustion
  • Fine particulate – respirable dust PM2.5

in test we conduct with a calibrated reference the budget indoor monitor typically showed results 10 x lower PM 2.5 than an accredited calibrated tool. Other items simply did not respond

So there is a reason why tested monitors cost £1,000’s and basic ones a lot lot less. This should change with the emergence of goods British Standards.

In the meantime, rather than look for specific numbers , look for trends. That is significant changes in the air quality

Workplace Exposure Monitoring & Training


Environmental Monitors(see have been offers a new affordable workplace exposure monitoring service that our clients appear to like .

Traditionally a company would invite a consultant in to physically perform a survey of the workplace. For medium to large companies, this tends to work well. A professional service is offered, a report is duly submitted and recommendations are made.

Our aim is to put the person responsible for workplace exposure monitoring with the organisation into the shoes of the consultant. In doing this we begin a journey for:

  • knowledge
  • process
  • exposure limitation

For this example we will consider inhalable and respirable dust

We offer:

  • Training
  • Methods of monitoring compliant with HSE requirements (MDHS methods)
  • The latest workplace exposure monitoring equipment to comply with the standard
  • Calibration of the equipment
  • Supply of preweighed filter medium
  • All filters and media are from a UKAS accredited laboratory
  • Basic report turn around time 2-3

We provide all the necessary knowledge, equipment and test materials to enable you to perform a test. Once the test is complete a report is issued approximately 2-3 weeks later.

The report will contain a summary of result, calculation to give a concentration and a 8 hour TWA ( time weighted average)

For further information please contact :


Tel:      01539 727878

Mob:  07799626406