Said to be ideal for sites with limited water availability the new Dustfighter AIO from Envirogard comes top-mounted to its own IBC.  An integral pump delivers water from the 1000 litre tank to the ring nozzle and the fan sends out a plume of fine water mist to the air.

Optionally Envirogard can equip the AIO with an automatic dosing unit to mix odour / dust suppressant concentrate to the water mist at point of use.

The tank holds enough water for 2.5 to 3 hours operation – but simply connect a water supply and the AIO will automatically re-fill the IBC when water is available – allowing the AIO to operate continuously.

Placed at ground level the new AIO will project water mist up to 15 metres horizontally in still air & the range increases when the AIO is elevated above ground level.  The fan’s adjustable tilt / swivel gives an arc of 110 degrees and a vertical tilt range of +10 to +50 degrees.

The AIO base has forklift pockets to facilitate relocation around site or on to the higher levels of buildings.  The AIO is available to hire from Envirogard – a division of Specialist Hires Limited.

Envirogard’s website provides further information about the AIO plus videos of this and other types of mist cannon available from Envirogard.

Envirogard operates a nationwide hire service.  For hire depot contact details and to view the full range of hire equipment see www.envirogard.co.uk.  Alternatively call Tel. 0161 320 8587 or email info@envirogard.co.uk.

The new study used satellite data from 2003 – 2020 to determine the effect of fuel regulations on pollution from cargo ships. The research team’s data revealed significant changes in sulfur pollution after regulations went into effect in 2015 and 2020. Their extensive data set can also contribute to answering a bigger question: How do pollutants and other particles interact with clouds to affect global temperatures overall? The study was led by the University of Maryland’s Tianle Yuan and appears in Science Advances.

Aerosols in the atmosphere are obviously a concern given their potential to be injurious to health. But they also often have a cooling effect on the planet because of the way they interact with clouds. Estimates of the extent of that effect vary by a factor of 10—not very precise for something so important.

“How much cooling the aerosols cause is a big unknown right now, and that’s where ship tracks come in,” said the study leader Tianie Yuan, an associate research scientist at the Goddard Earth Sciences Technology and Research (GESTAR) II Centre.

Navigating a sea of data

When pollutant particles from ships enter clouds low in the atmosphere, they decrease the size of individual cloud droplets without changing the total volume of the cloud. That creates more droplet surface area, which reflects more energy entering Earth’s atmosphere back to space and cools the planet.

Instruments on satellites can detect these differences in droplet size. And the air over the ocean is generally very clean, making the relatively narrow ship tracks that snake across the ocean easy to pick out. “Most of the original cloud is unpolluted, and then some of it is polluted by the ship, so that creates a contrast,” Yuan explained.

While ship tracks can be relatively obvious in satellite data, you have to know where to look and have the time and resources to search. Before advances in computing power and machine learning, Yuan said, PhD students could focus their entire thesis on identifying a group of ship tracks in satellite data.

“What we did is automate this process,” he said. His group “developed an algorithm to automatically find these ship tracks from the sea of data.”

This advance seems to have allowed them to generate a comprehensive, global map of ship tracks over an extended period (18 years) for the first time. Next, they will share it with the world—opening the door for anyone to dig into the data and make further discoveries.

Disappearing act

Even before pollution-limiting regulations were put into place, Yuan and his colleagues found that ship tracks didn’t occur everywhere ships were traveling. Only areas with certain types of low cloud cover had ship tracks, which is useful for adjusting the role of clouds in climate models. They also found that after Europe, the US, and Canada instated Emission Control Areas (ECAs) along their coastlines in 2015, ship tracks nearly disappeared in those regions, demonstrating the efficacy of such regulations for reducing pollution in port cities.

However, shipping companies didn’t necessarily reduce their pollution output across the board. Instead, they made changes to adapt to the new rules. Ports in northern Mexico (not part of the ECA system) saw increased activity, and pollution “hot spots” built up along the boundaries of the ECAs as ships altered their routes to spend as few miles as possible inside the restrictive zones.

In 2020, though, an international agreement set a much more restrictive standard for shipping fuel across the entirety of global oceans, rather than only near coastlines. After that, the only ship tracks the team’s algorithm could detect were those in the cleanest clouds. In clouds with even mild background pollution, the presumed ship tracks blended right in.

Climate conundrum

It seems obvious that reducing pollution from ships would produce a net benefit. However, because particles (such as shipping pollution) have a cooling effect when interacting with clouds, reducing them significantly could contribute to a problematic uptick in global temperatures.

That’s another reason it’s important to firm up the degree to which particulate pollution cools the planet. If the cooling effect of these pollutants and other particles is significant, humans will need to balance the need to prevent extensive warming with the need to reduce pollution where people and other species live—which creates difficult choices.

“Ship pollution alone can create a substantial cooling effect,” Yuan said, “because the atmosphere over the ocean is so clean.” There is a physical limit to how small cloud droplets can get, so at a certain point, adding more pollution doesn’t increase the clouds’ cooling effect. But over the ocean, because the background is largely unpolluted, even a small amount of pollution from ships has an effect.

Ocean pollution is also an outsize driver of the cooling effect of aerosols, because low clouds, which are most conducive to creating ship tracks, are more common over water than on land. And, as Yuan reminds us, “the ocean covers two-thirds of the Earth’s surface.”

The bigger picture

Yuan’s group are helping address this conundrum by continuing their work to define more precisely the role clouds play in climate. “We can take advantage
of the millions of ship track samples we have now to start to get hold of the overall aerosol-cloud interaction problem,” Yuan says, “because ship tracks can be used as mini-labs.”

By analyzing data from a relatively simple and well-controlled system—narrow ship tracks running through very clean clouds—they can, they say, come to conclusions they can be confident about.”

Other research teams can also use the team’s data set and algorithm to come to their own conclusions, amplifying the potential public impact of this work. That spirit of collaboration will help scientists and communities determine how best to approach global challenges like pollution and temperature change.

Engineering consulting firm Tetra Tech is using Zephyr® air quality monitors from air quality expert EarthSense as part of its dust monitoring service.

The service will enable construction companies, construction waste management sites and waste recycling centres to identify whether onsite activities, such as operation of diesel-powered machinery or the demolition of buildings, is affecting the levels of dust and to ensure emissions stay within safe guidelines.

Tetra Tech uses the EarthSense MyAir® web application to view the real-time and historic measurements taken by the Zephyr® monitors to identify the times and locations at which pollution spikes occur and to understand how workers and individuals living nearby are exposed to dust emissions. During such periods, measured data will be compared against urban background data to understand whether pollution episodes are related to its client’s activities.

The system is able to notify clients of any exceedances within 24 hours of occurrence, allowing the source to be identified and the correct mitigation measures put in place.

Researchers have measured the composition of fine dust at 22 locations in Europe, producing what they describe as a European map of the most important aerosol sources. The study was led by the Paul Scherrer Institute (PSI) and the findings have been published in the journal Environment International.

The researchers analysed data collected at 22 sites in both urban and rural areas across Europe. They have, they say, determined the major sources of organic aerosols – stemming both from natural and from anthropogenic sources – and their variations over the course of days, months and seasons.

Study co-author Imad El Haddad said the data could be used to improve air quality models. “These are used by epidemiologists to determine the aerosol sources that are most detrimental to human health.” In this way, policy makers could propose targeted measures to reduce the most dangerous aerosols, he said.

Combustion and traffic
While the composition of fine dust varies across the sites, the researchers say they have consistently identified the main source of aerosol pollution: residential heating with solid combustibles such as wood or coal.

“When solid fuel such as wooden logs, wood pellets, coal, or, in some countries, peat is used for residential heating, a lot of fine dust is released into the air and harms the health of the local population,” says Gang Chen, an aerosol researcher at PSI and the first author of the new publication. “In contrast to power plants, which have strict regulations and filter systems, the regulations regarding residential heating emissions are not sufficiently stringent for most European countries, including Switzerland.” In rural areas of the Alps, for example, many homes are still heated with solid combustibles. “Wood is a natural material. This is probably why many people are not aware of how health-damaging it is to burn wood,” adds Chen, who works in the Research Group for Gasphase and Aerosol Chemistry at PSI, headed by André Prévôt, who led this international study. With their work, the researchers hope to increase public awareness about the impact of residential combustion on air quality.

Traffic is another considerable source of fine dust. While traffic exhausts have been subject to strict regulations since the 1990s, non-exhaust emissions such as tire wear and brake wear deserve more attention in order to improve air quality, the scientists say.

A standardised protocol
The data for the new publication comes from 22 measuring stations in 14 countries, spread across the European continent, where various universities and other institutions operate their own aerosol measuring stations. The PSI researchers developed a standardised protocol for evaluating the data and determining the aerosol sources. This study is the main outcome of the international project “Chemical On-Line cOmpoSition and Source Apportionment of fine aerosoL” (COLOSSAL) and hence has a joint authorship of 70 collaborators.

Crucial to the study were also several long-standing EU research facilities, including the “Aerosols, Clouds, and Trace gases Research InfraStructure Network” (ACTRIS). ACTRIS and other pan-European research facilities were the starting point for the research, “producing high-quality long-term data on short-lived atmospheric constituents relevant for our regional climate and public health,” said El Haddad.

These facilities are the basis of several European research programmes, such as the “Research Infrastructures Services Reinforcing Air Quality Monitoring Capacities in European Urban & Industrial AreaS” (RI-URBANS). They also provide vital information for policy makers.

The researchers say they hope the publication will be understood as a stepping stone for a global mission. “We have shown for Europe that our standardised protocol for data analyses works. It can now be adopted by researchers everywhere,” says Chen. “PSI is world-leading in this work that allows us to attribute the measured aerosols to their sources. Next, we would like to expand our protocol in order to obtain aerosol maps of the entire world.”

In addition, the researchers envision that this type of data could soon be collected and analysed in real time. “This would make it possible to directly measure the effectiveness of measures taken to reduce aerosol pollution,” says Chen.

Setting guideline values
Currently, the WHO requires that the total amount of aerosols that are smaller than 2.5 micrometres in diameter not exceed 5 micrograms per cubic metre of air. The WHO has only recently redefined this guideline value; previously it was 10 micrograms per cubic metre. “However, both values are exceeded almost everywhere,” says El Haddad. “If we set the new value at 5 micrograms per cubic metre, then 99 percent of all people live in areas where this is currently not met. In Switzerland, at least, measured values fell just below 10 micrograms per cubic metre of air a few years ago – thanks to the efforts made so far to mitigate aerosol pollution.”

For the improvement of air quality to progress more efficiently in the future, regulators could lower the limit values specifically for those aerosols most harmful to health more than for others, the researchers argue. Chen adds: “Ultimately, it is about saving lives. Our data helps ensure that we set sound priorities when it comes to air quality.”

Environmental air pollution from vehicle exhaust and industrial output can trigger adaptive immunity–whereby the body reacts to a specific disease-causing entity. But sometimes this adaptive response misfires, prompting systemic inflammation, tissue damage, and ultimately autoimmune disease.

Examples of autoimmune disease include rheumatoid arthritis; systemic lupus erythematosus; inflammatory bowel diseases, such as ulcerative colitis; connective tissue disease, such as osteoarthritis; and multiple sclerosis.

Both the incidence and prevalence of these conditions have steadily increased over the past decade, the reasons for which aren’t entirely clear. And whether air pollution is linked to a heightened risk of autoimmune disease remains a matter of debate, say the researchers.

To try and shed some light on the issues, the researchers mined the national Italian fracture risk database (DeFRA) and retrieved comprehensive medical information on 81,363 men and women submitted by more than 3500 doctors between June 2016 and November 2020.

Most were women (92%) with an average age of 65, and 17866 (22%) had at least one co-existing health condition.

Each participant was linked to the nearest air quality monitoring station run by the Italian Institute of Environment Protection and Research via their residential postcode.

The researchers were particularly interested in the potential impact of particulate matter (PM10 and PM2.5). Levels of 30µg/m3 for PM10 and 20µg/m3 for PM2.5 are the thresholds generally considered harmful to human health.

Some 9723 people (12%) were diagnosed with an autoimmune disease between 2016 and 2020.

Information on air quality was obtained from 617 monitoring stations in 110 Italian provinces. Average long term exposure between 2013 and 2019 was 16 µg/m3 for PM2.5 and 25 µg/m3 for PM10.

Exposure to PM2.5 wasn’t associated with a heightened risk of an autoimmune disease diagnosis. But PM10 was associated with a 7% heightened risk for every 10µg/m3 increase in levels, after accounting for potentially influential factors.

Long term exposure to PM10 above 30 µg/m3 and to PM2.5 above 20 µg/m3 were associated with, respectively, a 12% and 13% higher risk of autoimmune disease.

And long term exposure to PM10 was specifically associated with a heightened risk of rheumatoid arthritis, while long term exposure to PM2.5 was associated with a heightened risk of rheumatoid arthritis, connective tissue diseases, and inflammatory bowel diseases.

Overall, long term exposure to traffic and industrial air pollutants was associated with an approximately 40% higher risk of rheumatoid arthritis, a 20% higher risk of inflammatory bowel disease, and a 15% higher risk of connective tissue diseases.

This is an observational study, and as such, can’t establish cause. And the researchers acknowledge several limitations which might have affected their findings.

These include: the lack of information on the dates of diagnosis and start of autoimmune disease symptoms; that air quality monitoring might not reflect personal exposure to pollutants; and that the findings might not be more widely applicable because study participants largely comprised older women at risk of fracture.

But air pollution has already been linked to immune system abnormalities, and smoking, which shares some toxins with fossil fuel emissions, is a predisposing factor for rheumatoid arthritis, they explain.

The compact, light-weight device provides real-time data and is intended to provide actionable insights for plant safety managers and the like.

AQBot is available in 14 variants supporting detection of a range of air pollutants including SO2, NO2, NO, TVOC, in addition to particulate matter like PM1, PM2.5, PM10, PM100. It also monitors noise.

Equipped with a quad-core ARM Cortex A-72 processor that enables it to handle multiple processes simultaneously, AQBot comes with 2GB RAM with 8 GB eMMC ROM that allows industries to store air quality data for 12 months in case of network connectivity disruptions.

The device supports communication protocols including MODBUS, CANBus, RS-485, RS-232 in addition to wireless communications like GSM, WiFi, and LoRa. It is powered by web-based user-friendly software.

Supported applications include environmental health and safety (EHS) monitoring, indoor air monitoring for industrial settings, process-control, and leak detections. AQBot can provide a comprehensive air quality monitoring system for paper and pulp industries, textile industries, leather industries, fisheries and cement manufacturing.

AQBot is described as “a comprehensive air quality monitoring system that offers accurate data with automation capabilities to suit Industry 4.0 requirements”.

The firm cites real-time performacne as a feature in addition to accuracy to ppb concentrations.

The monitor comes with a siren and strobe for audio and visual alerts to suit deployment in hazardous environments.

AQBot is housed in a NEMA 4X certified industrial-grade enclosure, and is made of composite polymers.

The research seemed to find that levels of carbon monoxide — a gas that indicates the presence of other air pollutants — increased sharply as wildfires spread last August. Carbon monoxide levels are normally lower in the summer because of chemical reactions in the atmosphere related to changes in sunlight, and the finding that their levels have jumped indicates the extent of the smoke’s impacts.

“Wildfire emissions have increased so substantially that they’re changing the annual pattern of air quality across North America,” said Rebecca Buchholz of the National Center for Atmospheric Research (NCAR), the lead author. “It’s quite clear that there is a new peak of air pollution in August that didn’t used to exist.”

Although carbon monoxide generally is not a significant health concern outdoors, the gas indicates the presence of more harmful pollutants, including particulates and ground-level ozone that tends to form on hot summer days.

The research team used satellite-based observations of atmospheric chemistry and global inventories of fires to track wildfire emissions during most of the past two decades, as well as computer modeling to analyze the potential impacts of the smoke. They focused on three North American regions: the Pacific Northwest, the central United States, and the Northeast.

Buchholz said the findings were particularly striking because carbon monoxide levels have been otherwise decreasing, both globally and across North America, due to improvements in pollution-control technologies.

The study was published in Nature Communications in April.

Wildfires have been increasing in the Pacific Northwest and other regions of North America, a phenomenon attributed to a combination of climate change, increased development, and land use policies. The fires are becoming a larger factor in air pollution.

To analyze the impacts of fires, Buchholz and her collaborators used data from two instruments on the NASA Terra satellite: MOPITT (Measurements of Pollution in the Troposphere), which has tracked carbon monoxide continually since 2002; and MODIS (Moderate Resolution Imaging Spectrometer), which detects fires and provides information on aerosols.

The scientists focused on the period from 2002, the beginning of a consistent and long-term record of MOPPIT data, to 2018, the last year for which complete observations were available at the time when they began their study. The results showed an increase in carbon monoxide levels across North America in August, which corresponded with the peak burning season of the Pacific Northwest. The trend was especially pronounced from 2012 to 2018, when the Pacific Northwest fire season became much more active, according to the emissions inventories. Data from the MODIS instrument revealed that aerosols also showed an upward trend in August.

To determine whether the higher pollution levels were caused by the fires, the group eliminated other potential emission sources. They found that carbon monoxide levels upwind of the Pacific Northwest, over the Pacific Ocean, were much lower in August — a sign that the pollution was not blowing in from Asia. They also found that fire season in the central US and the Northeast did not coincide with the August increase in pollution, which meant that local fires in those regions were not responsible. In addition, they studied a pair of fossil fuel emission inventories, which showed that carbon monoxide emissions from human activities did not increase in any of the three study regions from 2012 to 2018.

“Multiple lines of evidence point to the worsening wildfires in the Pacific Northwest as the cause of degraded air quality,” Buchholz said. “It’s particularly unfortunate that these fires are undermining the gains that society has made in reducing pollution overall.”

The findings have implications for human health because wildfire smoke has been linked to significant respiratory problems, and it may also affect the cardiovascular system and worsen pregnancy outcomes.

Buchholz and her co-authors used a computer model, the Community Atmosphere Model with a chemistry component, to simulate the movement of emissions from the Pacific Northwest fires and their impact on carbon monoxide, ozone, and fine particulate matter.

They ran the simulations on a supercomputer. The results showed the pollutants could affect more than 130 million people, including about 34 million in the Pacific Northwest, 23 million in the Central U.S., and 72 million in the Northeast.

Although the study did not delve deeply into the health implications of the emissions, the authors looked at respiratory death rates in Colorado for the month of August from 2002 to 2011, compared with the same month in 2012 to 2018. They chose Colorado, located in the central US region of the study, because respiratory death rates in the state were readily obtainable.

They found that Colorado respiratory deaths in August increased significantly during the 2012-2018 period, when fires in the Pacific Northwest — but not in Colorado — produced more emissions in August. “It’s clear that more research is needed into the health implications of all this smoke,” Buchholz said. “We may already be seeing the consequences of these fires on the health of residents who live hundreds or even thousands of miles downwind.”

Understanding cloud and rain formation mechanisms in the Amazon is a major challenge because of the complexity of the non-linear physical and chemical processes that occur in the atmosphere,” said Paulo Artaxo, a professor at the University of São Paulo’s Physics Institute (IF-USP) and co-author of an article on the study published in Science Advances.

The discovery enhances the accuracy of climate change studies based on mathematical models and simulations. “These nanoparticles of pollution [smaller than 10 nanometers] used to be overlooked in atmospheric calculations and models. The focus was on particles larger than 100 nm because these act as cloud condensation nuclei [on which water vapour condenses to form droplets] and change the rainfall regime. This study shows that smaller particles oxidize as they travel through the atmosphere, expanding rapidly until they reach the size necessary to become condensation nuclei,” Machado said.

The data was collected by instruments on board a special aircraft that flew over the Manaus pollution plume for about 100 kilometers (km) in 2014 and 2015 during the Green Ocean Amazon (GOAmazon) scientific project.

“Little was known about the role played by these nanoparticles in the rainfall regime,” Machado said. “It so happens that the Manaus area is unique in the world in the sense that it’s an open-air laboratory, a mega-city surrounded by forest at a great distance from other cities where we can investigate how a metropolitan area changes an environment similar to that of the pre-industrial era.”

Aerosols are microscopic solid or liquid particles suspended in the atmosphere. They are produced naturally by forests, as primary aerosols, and in the atmosphere from gases emitted naturally by forests that are known as volatile organic compounds (VOCs), as secondary aerosols. They can also be produced by human activities such as the burning of fossil fuels. The latter are the type investigated in this study.

According to Machado, aerosols of less than 10 nm emitted by vehicle exhausts, factories and power plants in the Manaus area form a pollution plume that is blown in a southwesterly direction by the prevailing winds. The researchers concluded that the particles grew rapidly during this journey.

How does PM affect rainfall?
“It’s very hard to estimate the effect of particulate matter on rainfall because of the large number of atmospheric variables that influence this interaction,” Machado said. “We therefore compared the pollution line with nearby areas that lie outside the plume. We found that the particles rapidly grow in size. By the time they’re 10 km out of Manaus, they’re larger, and at 30 km they can reach a large enough size to become condensation nuclei, affecting the formation of raindrops.”

Plume particulates compete
Cloud formation mechanisms are complex and involve many atmospheric parameters. Small aerosols interfere in raindrop condensation, but they may intensify or reduce rainfall depending on atmospheric conditions and above all on cloud formation at each moment.

According to Machado, the large amount of particulate matter in the plume creates a sort of competition for the water vapour present in clouds and the size of the droplets decreases as a result.

“For rain to fall, the droplets have to be a certain size,” he said. “What we call terminal droplet velocity has to be above the velocity of the upwelling air, or the cloud will be full of tiny droplets and no rain will fall.”

If a very strong vertical wind is blowing, however, it can drive this large mass of droplets to a higher altitude where they form ice particles and potentially fuel a fierce storm. “We found that as the particles grow and become condensation nuclei, scant rainfall results if they meet a small, warm cloud. The aerosols reduce the precipitation. However, if the cloud builds up to become a mass of cumulonimbus [dense, towering, vertical cloud], for example, the aerosols increase the precipitation,” he said. “In other words, even these small particles of pollution influence the rainfall regime.”

According to the researchers, the project will proceed on a broader basis and fresh data will be collected. This year the team will conduct an experiment called Chemistry of the Atmosphere: Field Experiment in Brazil (CAFE-Brazil), with the aid of a German aircraft that can fly as high as 15,000 m. Artaxo explained that similar studies using remote sensing are also being conducted at the 325 m ATTO tower in the heart of the Amazon Rainforest (more at: agencia.fapesp.br/29665).

“In the study just published, we collected data on a low flight path [at 4,000 m],” he said. “The German aircraft we’ll use for our next collections is one of the most sophisticated flying laboratories in existence, so we’ll be able to conduct an experiment designed to produce an understanding of key physical and chemical issues in the production of aerosols, clouds and rain that are still a mystery to us.”

A new air purifier is seemingly designed – somewhat uniquely – to catch airborne dust before it settles on floors and surfaces. Announced in February by Swedish firm Blueair, the DustMagnet also seems unusual in its departure from anything machine-like in appearance having been designed to look like a piece of furniture.

The technology is designed to attract airborne dust particles like a magnet before they settle on floors and surfaces. Thanks to a powerful airflow in combination with two positively charged pre-filters, airborne dust is captured and removed, resulting in less time spent dusting and vacuuming.

In addition to dust, the device also seemingly “inactivates” bacteria and viruses and removes 99.97% of allergens, pollen, mould, pet dander and microplastics down to 0.1µm.

A proprietary technology, HEPASilent, apparently means the device can use less dense filters than traditional air purifiers, thanks to a combination of electrostatic and mechanical filtration. “Therefore the DustMagnet can produce more clean air at less air pressure, meaning whisper silent operation and less energy use than a light bulb.”

Available in two sizes, the DustMagnet 5240i is independently verified to clean rooms between 20m² and 48m² in size while the DustMagnet 5440i is designed for rooms between 33m² and 79m² in size.

Another seemingly unusual feature is an Auto mode function whereby a smart sensor monitors real-time air quality conditions and auto-adjusts
to optimise cleaning performance.

It’s a general truism that you can’t manage what you don’t measure, an idea clear to Lord Kelvin over 100 years ago¹ and enacted by health & safety professionals when they carry out risk assessments (or check the effectiveness of controls).

For dust and particulates, this has typically involved the gravimetric method using a personal sampling pump, an appropriate sampling head for the size fraction of interest (total, inhalable, or respirable), and a filter that is weighed before and after exposure. And since the sampling pump is designed to maintain a constant flow (even when the filter increasingly gets loaded), the concentration can be calculated in terms of mass per unit volume (g/m3). This method has been used worldwide for over 60 years, meaning hazard legislation and occupational exposure limits (OEL) have been established on this gravimetric basis.

So, if ‘it’ (the measurement technique) isn’t broken why try and fix it? Well, it’s often through innovation that ways can be found to make measurements more quickly, more accurately, or at a reduced cost. Who would argue against that?

However, there are normally instrumentation standards that need to be met and air sampling pumps are no exception along with sound level meters, noise dosimeters, and human vibration meters. Pumps, for example, must meet ISO 13137² in several areas including flow stability and pulsation. It’s also true that such standards tend to lag technology by as much as a decade, which can frustrate market adoption of new technology as well as a manufacturer’s return on their investment.

Real-time milestones
A precedent was set in the US for an alternative real-time method for the measurement of coal dust. After extensive testing, it was found that the proposed personal dust monitor met NIOSH sampling accuracy requirements³; equivalency to the in-service coalmine personal dust sampling (gravimetric) sampler was published in a peer-reviewed journal and a new Federal rule was enacted4 allowing its use.

A similar precedent has been set in France. The FCBA Technical Institute for the woodworking industry was tasked with reassessing direct reading methods because many companies were failing to meet the exposure limit but there was an unacceptable financial burden on SMEs due to the testing with the reference gravimetric method. However, earlier studies had not been able to satisfactorily establish equivalency. An empirical relationship has now been established for the Casella Microdust Pro in conjunction with the Apex2 sampling pump, as a real-time means to demonstrate the effectiveness of controls, for example, local exhaust ventilation (LEV).

The common denominator in the US and France is that the method validation process has taken hundreds of tests, conducted over several years but most importantly has only been established for a specific type of dust i.e. coal and wood respectively.

As well as a tool for general LEV use, the Microdust Pro’s two-part design allows the probe to be placed in awkward-to-reach places such as ducts but in this application, equivalency is not required for checking performance pre- and post-filtering, although it can be calibrated gravimetrically for a given dust type. It has also been a favourite tool for walk-through surveys to provide an initial risk assessment in accordance with UK regulation 6(1a) of the Control of substances Hazardous to Health (COSHH) Regulations, while regulation 10 states that “the employer shall ensure that the exposure of employees to hazardous substances to health is monitored in accordance with a suitable procedure”. Further guidance on exposure monitoring can be found in the UK’s Health and Safety Executive’s HSE’s Monitoring strategies for toxic substances5 and specific methods for different dust types are also available from the HSE6 as they are from NIOSH in the USA.

The accompanying approved code of practice (ACOP)7 goes on to state that Suitable sampling, analytical, and quantification procedures should be standardised and validated by authorities such as HSE, the British Standards Institution (BSI) or other reputable authoritative agencies such as CEN, the International Standardization Organization (ISO) and the US National Institute for Occupational Safety and Health (NIOSH). Employers should ensure that the procedures used are sufficiently sensitive for the situation being monitored and of proven effectiveness for assessing adequate control.

Light work?
Looking into the suitability of real-time inhalable dust monitors, the HSE published a comparison study8 which compared a raft of commercially available products, many using a photometer design, which means using a forward-light-scatter technique. Typically, a modulated laser light source passes into a measurement chamber where under clean-air conditions, all light is prevented from following a direct route to reach the laser detector by a light stop. When dust particles enter the sample volume, the beam of laser light is scattered within a narrow-angle and some of it can reach the detector by indirect routes.

However, it’s rather like trying to weigh someone with a torch based on their shadow which points to the limitation of this method. By using a narrow-angle of scattering, the instrument is made less sensitive to variations in the refractive index and colour of the measured particulates, but they are still prone to potentially large concentration and linearity errors.

Additionally, the technique is only suitable for larger (inhalable) particles but there are of course OELs for both the inhalable and (the smaller) respirable fractions such as those found in the UK’s EH409 or other countries published exposure limits.

However, despite limitations, the report concluded that two of the units under test showed promise, but this was a decade ago and it is not clear whether this type of study would constitute the ‘standardised and validated’ requirements of the ACOP? Indeed, there is a cautionary note in the latter, which states that “You may use alternative methods to those set out in the Code in order to comply with the law. However, the Code has a special legal status. If you are prosecuted for breach of health and safety law and it is proved you did not follow the relevant provisions of the Code you will need to show that you have complied with the law in some other way or a Court will find you at fault”.

Not wishing to be considered a Luddite opposed to new technology or ways of working but ‘buying into’ the latter may be a case of caveat emptor. Should you be in any doubt, it’s wise to stick to the approved method since when it comes to workers’ health one can’t be too careful!

References
1. Popular lectures and addresses by Kelvin, William Thomson, In Three Volumes Vol.1. Constitution of Matter, London Macmillan 1889 2. ISO 13137:2013 Workplace atmospheres — Pumps for personal sampling of chemical and biological agents — Requirements and test methods 3. NIOSH Report of Investigations (RI) 9669, Laboratory and field performance of a continuously measuring respirable dust monitor, September 2006 4. CFR 30 Part 74, COAL MINE DUST SAMPLING DEVICES, 2009 5. Monitoring strategies for toxic substances, HSG 173, Second Edition, 2006, Health and Safety Executive 6. Methods for the determination of hazardous substances guidance (hse.gov.uk) 7. The Control of Substances Hazardous to Health Regulations (COSHH), Approved Code of Practice, HSE L5 (Sixth edition), Published 2013. 8. Direct-Reding Inhalable Dust Monitoring- An Assessment of Current Measurement Methods. Andrew Thorpe & Peter Walsh, Health and Safety Laboratory, June 2012
9. EH40/2005 Workplace exposure limits (Fourth Edition 2020)