Five Common Misconceptions about Air Filters

Five Common Misconceptions about Air Filters

Five Common Misconceptions About Air Filters

September 20, 2021

There’s lots of information out there about air filters, particularly in the time of COVID-19. But for industrial air filtration and pressurisation in hazardous environments, we find the same misconceptions popping up repeatedly.

1) Cabin pressure is enough to protect operators

Positive pressure does keep hazardous dust from entering into the cab through tiny openings. However, it doesn’t stop hazardous dust from entering the cabin. Ambient air is pumped into the cabin to create a positive pressure difference between inside and outside. This ambient air, however, still contains all of the harmful airborne particulates outside!

By filtering this fresh air, purified and clean air enters the cabin and blows into the operator breathing zone.

2) Air filters will restrict airflow in the vehicle

In traditionally designed pressurisers, the higher the efficiency class of your filter, the less airflow entered the cabin. This is why many brands market MERV-16 or EPA filters as the optimal combination between airflow, price and filtration efficiency.

However, BreatheSafe High Pressure Filtration systems can maintain appropriate airflow, even with higher classes of filtration. As standard, we sell HEPA H14 filters in our pressure systems. We believe that filtration is a significant factor in protecting the enclosed area from hazardous dust. This airflow is capable because of the brushless motors and advanced intelligent motor power control of in-cabin pressure.

3) HEPA air filters are only 99.99% effective

HEPA classification works on its effectiveness in filtering particles at the Most Penetrating Particle Size (MPPS). Particles of approximately 0.3 μm – the MPPS – are the hardest to catch. The size at which the air filter has its lowest arrestance value and penetrates through filtration processes at the most common rate. For this reason, the European standard EN 1822 assesses the filtration performance of the filter by measuring the penetration of 0.3 μm sized particles. Much smaller nanoparticles are easier to catch.

Tests conducted by NASA showed that HEPA filters are highly effective in capturing up to 100% of nanoparticulate contaminants and larger particles greater than 0.3 μm. However, for particles around the MPPS, there is a tiny drop in filtration efficiency.

Classic Collection Efficiency Curve with Filter Collection Mechanisms

According to EN 1822, a HEPA filter must remove at least 99.95% of particles sized 0.3 μm or larger. US government standards require a filter to remove 99.97% of particles sized 0.3 μm to qualify as HEPA.

That is why HEPA filters are actually more than 99.99% effective at removing hazardous particles from the air but are rated as so. These MMPS particles are still dangerous, which is why the higher the %, the better it is for your health.

4) Replace air filters when they look dirty

A common question we receive is, isn’t replacing filters expensive?

We’ve found that many customers are replacing their filters well before they are full. It is particularly worrying because the fuller a filter is, the more effective it is. Our INPRESS system includes automatic motor power control that increases when pressure within the cabin decreases. Cabin pressure decreases over time due to the filter filling up, and when the INPRESS sees it getting lower, it increases blower speed to maintain the pressure setpoint. In addition, the INPRESS will let you know when the filter is too full when the motor is going at excessive speeds. This extends filter life and prevents early changing, saving you money.

With motor control, it also blows through lower volumes of air to maintain that pressure, meaning less debris and the particulate matter goes through the filter, filling it up slower. We have introduced a new touch screen display that shows in real-time the capacity of our pressuriser, which means sites will know when to replace filters! That’s a cost-saving that can be multiplied by all the machines equipped with BreatheSafe systems.

BreatheSafe HEPA filter after 2800 hours of use, and still effective

5) An air filter will heat up the cabin

Traditional pressuriser designs run their motors at 100% consistently to maintain airflow, resulting in a noisy, hot machine and atmosphere. An uncomfortable operator enclosure can result in untrained operators winding down windows for fresh air, letting all the hazardous particles inside.

However, we design BreatheSafe High Pressure Air Filtration systems to blend with the machines pre-existing airconditioning system, so the fresh, clean air is cooled before entering the cabin. Beyond that, our motors run with minimal power and still provide substantial airflow, maintaining a comfortable enclosure in even the hottest environments.

How many of these misconceptions did you believe? Let us know!

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Data Monitoring: The Key to Success in Minimising Exposure to Dust

Data Monitoring: The Key to Success in Minimising Exposure to Dust

Data Monitoring: The Key to Success in Minimising Exposure to Dust

August 31, 2021 (Photo updated October 19, 2023)

Remote data monitoring is the way forward for site operations—real-time warnings and long-range data to review help set risk management plans to prevent lung disease.  Having fully automatic data logging and alerting removes many opportunities for human error and is cost-effective in the long term. Access to this data provides convenient visibility and allows managers to make informed decisions to increase safety and productivity in the workplace.

Monitor System Performance

The greatest asset of a risk management plan is to have actual proof that an installed system is performing as designed; to the required level and outcome.

Long-term data log values assist in evaluating the gains in performance. Data on the filter’s efficiency and potential events leading to exposure risks helps evaluate the installed filtration system. If there are many exposure events or the filter is filling quickly, it allows maintenance extra access to understanding where performance hindering lies. However, if performance is recorded as being successful and efficient, it can justify the costs of the filtration system and allow calculations of value provided.

The performance gains are significant when utilising innovative technology such as the extended service cycle of brushless motors and filtering the correct volume of fresh air. BreatheSafe High Pressure Air Filtration systems automatically control these important performance aspects and record data for downloading to ensure optimal performance.

Real time data monitoring graph from INPRESS TS of pressure change over time to minimise exposure of dust

Monitor Operator Training Effectiveness

The most crucial factor is keeping the working environment clean and free from airborne particulate matter, which can only be achieved with operator involvement.

Training must be part of the respirable dust risk management plan to engage operators. Training requires measures that must be encouraged and kept, such as always keeping doors and windows closed. Minimising and controlling all potential events that can introduce contamination inside the cabin with respirable particulate.

By recording the number of events and the reason behind the event, supervisors can identify individuals requiring further training or finding areas of improvement in the training program. 

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BHP Autonomous Cabinet Field Trial

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Caterpillar 793F Autonomous Field Trial


BHP Trial

In 2018, BHP consulted with BreatheSafe concerning airborne mine dust mitigation for their Autonomous 793F trucks. A field trial was started to deliver a full system to mitigate airborne dust, heat and water ingress with their Caterpillar fleet of Autonomous Trucks – electrical cabinet.

The Problem

The ongoing issue is airborne mine dust: there is dust build-up inside the electrical cabinet. This is causing electrical systems to run hot due to dust accumulation and electrical connections to corrode and fail when contaminated with abrasive particles. Airborne mine dust can comprise different materials that affect components with abrasive and corrosive properties.

Also, temperature control issues are critical in enclosure design. When temperature increases, it will affect electrical components. The optimal temperature for most electrical equipment is between 40⁰C to 50⁰C. Thus, when the internal temperature of electrical components rises above the optimal range, then their lifespan will decline. Further complication is OEM electrical cabinet has a small opening door which makes servicing difficult and time consuming


The Solution

BreatheSafe custom design insulated cabinet enclosure: equipped with HEPA fresh air pressurisation integrated with temperature sensing and active cooling plus large access door; the key features are:

  • Keeps electrical components dust free.
  • Dramatically reduced maintenance costs.
  • Active cooling maintains enclosure internal temperature below 50⁰C.
  • Automatic Pressure Control (positive pressure is always maintained).
  • Remote monitoring: ongoing data for temperature and positive pressure.
  • Long life brushless electrical motor.
  • HEPA filters mitigate dust particulate down to submicron level.
  • Large door makes easy access to internal components.
  • No tools required for all dust mitigation system servicing.
  • Full service back up

The Result

BreatheSafe autonomous cabinet enclosure can effectively control airborne dust down to submicron level with active cooling program. As soon as temperature rises above 45⁰C then pressuriser motor goes into high speed to cool enclosure effectively maintaining below 50⁰C.

Remote monitoring data has assisted with maintenance schedule routine with real time data for dust loading calculation.

Auto pressure control maintains positive pressure inside enclosure regardless of wind speed or as vehicle moves forward. Engine air pre-cleaner ejects coarse dust to successfully extend HEPA filters lifecycle.

Trial success, BHP has placed order to convert fleet to BreatheSafe custom enclosure.

RPME is the best practice to stop respirable dust

RPME is the Best Practice to Stop Respirable Dust

June 06, 2021

BreatheSafe Air Pressuriser System installed on a Komatsu PC490LC-11

RPME Respirable Particulate Mitigation Ecosystem:

A system, or group of interacting elements designed to protect the operator’s breathing zone environment

Bolting a pressuriser to a cabin without proper seals will not function well at all. Leaks in the cab will allow dust contamination to enter. The filters will be loaded by dust much sooner due to the higher volume (positive pressure) of air delivered to maintain a higher pre-set pressure (Positive pressure leakage).

The issues:

  1. A cabin by itself can no longer be assumed to resolve issues with respirable dust
  2. An environmental cabin serves as the primary method of dust control for operators for both surface and underground
  3. An environmental cabin/enclosure simply means that it can maintain a pre-set pressure level, for example: 20 pascals minimum.
  4. The effectiveness of the cab is maintained when the operator remains inside with doors and windows closed
  5. The HVAC must be well designed to cope with fresh air pressurisation (Hot/humid outside air)

BreatheSafe can assist with systems upgrades (Condensing) in very hot situations

  • The fresh air pressuriser is filtered with HEPA media to separate respirable dust
  • HEPA return air filters are fitted to control respirable dust inside the cabin (Particulate matter in shoes and clothes)
  • The benefit is HVAC internal components remain dust free; reducing unscheduled repairs and/or machine standing down due to failure.


– Auditing and testing the entire system

The cabin requires proper sealing to maintain positive pressure: Door and window seals must be replaced as soon as damage and/or leaks are detected.


The best practice is to have a multitude of systems in place: Pre-cleaner and a fresh air HEPA pressuriser system matched to an environmentally sealed structure and which is pressurised to a controlled pre-set level. Procedures of sealing all gaps and making sure that window and door seals are in good working order are also required. The cabin must be kept clean always, with doors and windows remaining closed at all times.

Utilising a computer-controlled display system and citing an international standard such as EN15695 (Hazardous substances) is necessary as it states that the ideal pressure level is between 20 to 50 pascals for ONE person cabin. EN15695 imposes an absolute minimum: 20 pascals with a pressure display (Operator awareness) or 50 pascals without a pressure display.

Breathe-Safe system EN15695-4 system consists of:

  • Environmental cabin/enclosure (Tight against airborne particulate)
  • Pre-cleaner to expel coarse particulate (Extends the life of HEPA media)
  • HEPA filter forced ventilation (Fresh air pressuriser)
  • HEPA return air filter
  • Display (Operator awareness)
  • Remote Monitoring (Site management/maintenance)
  • Activated carbon media for Gaseous particulate
  • Fresh air volume minimum is 30m³/h for one person cabin to avoid CO2 build up

Exposure to respirable dust impacts worker health in the short and long term as well as on productivity for both man and machine. The other issue that needs to be understood is that fine dust does cause HVAC system contamination (HVAC internal restriction) over time and leads to unscheduled maintenance situations and other related issues such as underperforming climate control. The BreatheSafe ecosystem is effective at limiting respirable dust exposure to almost zero levels for the operator. Remote monitoring can be used for data management and systems review. It can also be used to provide training for operators where a window or door have been left open.

The conclusion is the sum of elements to protect the operator/s must remain effective over the entire lifecycle of the cabin/enclosure.

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DPM (Diesel Particulate Matter) is a group one carcinogen

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June 6, 2021

Aerosol & DPM: controlling hazardous submicron respirable particles

At mineral processing sites, there are lots of substances that can remain airborne for days depending on the size of the particulate matter (PM).

There are sites that must mitigate against sulphur dioxide and other toxic gases with mild to dangerous health effects depending on concentration.

The emerging issue is diesel exhaust emissions emissions which are classified as DPM (Diesel Particulate Matter) these may be the some of the most hazardous exposures at underground mines and above ground operations. The composition of diesel particulate matter is complex and the reason that there is so much potential risk to health.

Diesel exhaust includes more than forty substances that are listed as hazardous air pollutants and fifteen are listed as carcinogenic to humans.

Furthermore, chemical reactions in the atmosphere contribute to secondary particulate matter reactions; again, with carcinogenic properties. Diesel combustion particles are made up of fine particles (PM 2.5) combined with a high level of ultrafine particles (PM 0.1) The particulate that is in the PM2.5 range deposit in the deep tissue of the lung exactly where the human body is not able to expel these.

The fraction at PM 0.1 has been shown to cross from airways into our bloodstream.

The solution is well ventilated areas with isolation measures and the best practice is to utilize a multitude of controls. An environmental cabin / enclosure equipped with fresh air pressurisations is the best practice to ensure a safe work environment for the operator (Doors and windows must remain closed always).

The cabin / enclosure must be installed with HEPA filtration to separate airborne fine particles.

The cabin / enclosure must also be equipped with an activated carbon filter phase to adsorb airborne ultrafine particles.

Sites in Western Australia utilising HEPA filters in a fresh air pressurised cabin have halved their exposure values.

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