Monthly Archives: September 2020

Airborne Dust: A Hazard to Human Health

I trust you will enjoy today’s article.  Have a great day!

Airborne Dust: A Hazard to Human Health

Airborne Dust: A Hazard to Human Health, Environment and Society
Author: By Enric Terradellas, Slobodan Nickovic and Xiao-Ye Zhang

https://public.wmo.int/en/resources/bulletin/airborne-dust-hazard-human-health-environment-and-society

“Over the last decade, the scientific community has come to realize the important impacts of airborne dust on climate, human health, the environment and various socio-economic sectors. WMO and its Members, having started implementation of monitoring, forecasting and early warning systems for airborne dust in 2004, are at the vanguard on evaluating these impacts and developing products to guide preparedness, adaptation and mitigation policies.

This article will first provide an overview of the dust cycle and discuss its interaction with weather, the climate system, and terrestrial and marine ecosystems, before looking at its impacts on health and diverse economic sectors. It will then highlight the international network coordinated by WMO and its ambitious plan for providing policy-oriented products. The intent is to raise awareness in National Meteorological and Hydrological Services (NMHSs) on the extent of the adverse impacts of airborne dust and to inform readers of WMO efforts to understand these better. The article highlights the WMO initiative to provide operational services that can facilitate dust forecasting and early warning in order to invite other interested organisations to actively participate in this important work.

The Dust Cycle
Dust storms are common meteorological hazard in arid and semi-arid regions. They are usually caused by thunderstorms, or strong pressure gradients associated with cyclones, that increase wind speed over a wide area.

These strong winds lift large amounts of sand and dust from bare, dry soils into the atmosphere, transporting them hundreds to thousands of kilometres away.

Gravity keeps dust pinned down on the Earth surface. The heavier a dust particle – due to size, density or the presence of water in the soil – the stronger the gravitational force holding it down. A dust storm can only occur when the wind force exceeds the threshold value for the loose particles to be lifted off the ground. Vegetation serves as a cover, protecting the Earth surface from this wind (Aeolian) erosion. Thus, drought contributes to the emergence of dust storms, as do poor farming and grazing practices or inadequate water management, by exposing the dust and sand to the wind.

Some 40% of aerosols in the troposphere (the lowest layer of Earth’s atmosphere) are dust particles from wind erosion. The main sources of these mineral dusts are the arid regions of Northern Africa, the Arabian Peninsula, Central Asia and China. Comparatively, Australia, America and South Africa make minor, but still important, contributions. Global estimates of dust emissions, mainly derived from simulation models, vary between one and three Gigatons per year.

Once released from the surface, dust particles are raised to higher levels of the troposphere by turbulent mixing and convective updrafts. They are then transported by winds for lengths of time, depending on their size and meteorological conditions. Gravitation remains the major force pulling dust particles back down to the surface. Together with impaction and turbulent diffusion, it contributes to what is called dry deposition. As larger particles sediment more quickly than smaller ones, there is a shift toward smaller particle sizes during transport. Dust is also washed out of the atmosphere by precipitation – wet deposition. The average lifetime of dust particles in the atmosphere ranges from a few hours for particles with a diameter larger than 10 μm, to more than 10 days for the sub-micrometric ones.

Interaction with weather and climate
Aerosols, particularly mineral dusts, impact weather as well as global and regional climate.4 Dust particles, especially if coated by pollution, act as condensation nuclei for warm cloud formation and as efficient ice nuclei agents for cold cloud generation. The ability of dust particles to serve as such depends on their size, shape and composition, which in turn depend on the nature of parent soils, emissions and transport processes. Modification of the microphysical composition of clouds changes their ability to absorb solar radiation, which indirectly affects the energy reaching the Earth’s surface.5 Dust particles also influence the growth of cloud droplets and ice crystals, thus affecting the amount and location of precipitation.

Airborne dust functions in a manner similar to the greenhouse effect: it absorbs and scatters solar radiation entering Earth’s atmosphere, reducing the amount reaching the surface, and absorbs long-wave radiation bouncing back up from the surface, re-emitting it in all directions. Again, the ability of dust particles to absorb solar radiation depends on their size, shape and mineralogical and chemical composition. The vertical distribution of dust in the air (vertical profile) and the characteristics of the underlying surface are also required to quantify this impact.

Impacts on human health
Airborne dust presents serious risks for human health. Dust particle size is a key determinant of potential hazard to human health. Particles larger than 10 μm are not breathable, thus can only damage external organs – mostly causing skin and eye irritations, conjunctivitis and enhanced susceptibility to ocular infection. Inhalable particles, those smaller than 10 μm, often get trapped in the nose, mouth and upper respiratory tract, thus can be associated with respiratory disorders such as asthma, tracheitis, pneumonia, allergic rhinitis and silicosis. However, finer particles may penetrate the lower respiratory tract and enter the bloodstream, where they can affect all internal organs and be responsible for cardiovascular disorders. A global model assessment in 2014 estimated that exposure to dust particles caused about 400 000 premature deaths by cardiopulmonary disease in the over 30 population.6

Some infectious diseases can be transmitted by dust. Meningococcal meningitis, a bacterial infection of the thin tissue layer that surrounds the brain and spinal cord, can result in brain damage and, if untreated, death in 50% of cases.7 Outbreaks occur worldwide, yet the highest incidence is found in the “meningitis belt”, a part of sub-Saharan Africa with an estimated population of 300 million. These outbreaks have a strong seasonal pattern – many studies have linked environmental conditions, such as low humidity and dusty conditions, to the time and place of infections.8 Researchers believe that the inhalation of dust particles in hot dry weather may damage nose and throat mucosa creating favourable conditions for bacterial infection.9 Moreover, iron oxides embedded in dust particles may enhance the risk of infection.10

Dust also plays a role in the transmission of valley fever – a potentially deadly disease – in the Southwest of the United States and in the Northern Mexico by acting as a transporter of Coccidioides fungi spores.

Impacts on the environment and society
Surface dust deposits are a source of micro-nutrients for both continental and maritime ecosystems. Saharan dust is thought to fertilize the Amazon rainforest, and dust transports of iron and phosphorus are know to benefit marine biomass production in parts of the oceans suffering from the shortage of such elements.11 But dust also has many negative impacts on agriculture, including reducing crop yields by burying seedlings, causing loss of plant tissue, reducing photosynthetic activity and increasing soil erosion.

Indirect dust deposit impacts include filling irrigation canals, covering transportation routes and affecting river and stream water quality. Reductions in visibility due to airborne dust also have an impact on air and land transport. Poor visibility conditions are a danger during aircraft landing and taking off – landings may be diverted and departures delayed. Dust can also scour aircraft surfaces and damage engines.

Dust can impact on the output of solar power plants, especially those that rely on direct solar radiation. Dust deposits on solar panels are a main concern of plants operators. Keeping the solar collectors dust-free to prevent particles from blocking incoming radiation requires time and labour.”

______________________________

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

Littering and Improper Garbage Disposal – Effects

What are the effects of littering and improper garbage disposal on our environment?  These articles answer those tough questions.

____________________________

The Effects of Littering on the Environment & Animals

https://sciencing.com/effects-littering-environment-animals-8634413.html

Updated April 17, 2018
By Catherine Irving

“As humans consume natural resources, they, too, create byproducts that enter Earth’s varied ecosystems. Plastic waste, water pollution, soil runoff, and jars and bottles make up just a few of the human-made products and byproducts that can harm the Earth and the species that live on it. The damage can be physical — six-pack rings strangling marine life — or chemical — fertilizers causing algal blooms — but in either case, they can cause lasting damage to the flora and fauna of an area.

Plastic Waste
Discarding plastic products, including grocery sacks, rapidly fills up landfills and often clog drains. When plastic litter drifts out to sea, animals like turtles or dolphins may ingest the plastic. The plastic creates health problems for the animals including depleting their nutrients and blocking their stomachs and intestines. Animals cannot break down plastic in their digestive system and will usually die from the obstruction. Pieces of plastic can also get tangled around animals’ bodies or heads and cause injury or death.

Water Pollution
Litter in Earth’s water supply from consumer and commercial use creates a toxic environment. The water is ingested by deer, fish and a variety of other animals. The toxins may cause blood clotting, seizures or serious medical issues that can kill animals. The toxic water may also kill off surrounding plant life on riverbanks and the bottom of a pond’s ecosystem. When humans eat animals that have ingested compromised water supplies, they also can become sick.

Soil Runoff
Runoff from litter, polluted water, gasoline and consumer waste can infiltrate the soil. The soil absorbs the toxins litter creates and affects plants and crops. The agriculture is often compromised and fails to thrive. Animals then eat those crops or worms that live in the soil and may become sick. Humans who eat either the crops or the animals feeding on the infected agriculture can also become ill.

Jars and Bottles
Discarded jars and bottles usually do not biodegrade naturally and add to humanity’s mounting litter problem. The litter remains in landfills and clogs sewers, streets, rivers and fields. Crabs, birds and small animals may crawl into the bottles looking for food and water and become stuck and slowly die from starvation and illness. The World Wide Fund for Nature reported some 1.5 million tons of plastic waste from the water bottling industry alone.”

Littering and Improper Garbage Disposal

The Effects of Improper Garbage Disposal

https://sciencing.com/the-effects-of-improper-garbage-disposal-4877867.html

Updated December 11, 2018
By Julie Boehlke

“Tossing everyday items into the trash can seem like second nature to many people. If you are implementing recycling techniques into your lifestyle, you are taking a positive step toward helping the environment. Learner.org notes that in the U.S. alone, over 230 million tons of trash is produced each year. Less than 25 percent of that waste is recycled and the rest ends up in landfills, incinerated or in ditches and roadsides. Improper garbage disposal isn’t just an eyesore; it poses a serious threat to nature.

Soil Contamination
It is important to learn the basics of recycling so that the waste that does end up in landfills can be disposed of properly. Plastics, metals, papers and certain types of glass can all be recycled at your local recycling center. If you take the time to send these items to recyclable locations, the items can be reused and returned to consumers. They won’t end up as trash or hurting the environment. If recyclables are placed into the ground they can potentially contaminate the surrounding soil. The Western Courier shares with readers that as plastic water bottles break down they can release DEHA, a type of carcinogen that can cause reproductive problems, liver issues and weight loss. This type of chemical can leach into the soil and cause contamination that can reach plant and animal life as well as water sources. Newspapers or paper that contains ink can be toxic to the soil as well. If the garbage is dumped or not contained properly in a landfill it will contaminate the surrounding ground.

Air Contamination
When disposing of garbage that contains harmful chemicals such as bleach, acid or oil it is important that it is disposed of in approved containers and labeled correctly. Paper, plastics and other materials that are burned can contaminate the air when they are burned. Over time the chemicals can build up in the ozone layer. If they contain toxic chemicals like dioxin they can reach the air that people breathe and cause a public health risk. Garbage that is disposed of improperly can also begin to release methane gases. According to the Energy Information Administration, these gases are greenhouse gasses that can destroy the earth’s ozone layer and contribute to significant climate changes or global warming.

Animals and Marine Life
Humans are not the only ones affected by improper garbage disposal—animals are too. Conservation International notes that garbage dumping and discharging raw or untreated sewage can threaten marine life and animals who come in contact with the water. When waste forms a cluster or algal bloom, the area can suffocate and contaminate sea bottom habitats such as coral and fish reducing their numbers. This contamination not only destroys their habitat it can also affect human consumption as fish and shellfish that were feasting off of contaminated areas reach fishermen and are caught for human consumption. Old fishing lures, plastic bottles, rope, Styrofoam, cigarette butts and fishing lines can be consumed by marine animals leading to the death of millions each year according to Conservation International.”

____________________________

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

Letting The Sunshine In

House dust contains a myriad of bacteria – what can we do to help?

We’re surrounded! House dust is a rich source of bacteria

https://phys.org/news/2008-04-house-rich-source-bacteria.html

“If you’ve always suspected there are unknown things living in the dark and dusty corners of your home and office, we are now one step closer to cataloging exactly what might be lurking in your indoor environment. Buildings have their own pattern of bacteria in indoor dust, which includes species normally found in the human gut, according research published in BMC Microbiology.

The microbial flora from indoor dust samples from two buildings was complex and dominated by bacterial groups originating from users of the buildings. The Finnish-based research team investigated the species level diversity and seasonal dynamics of bacterial flora in indoor dust by sequencing DNA from the dust samples collected.

“People spend most of their lives in different indoor environments: homes, schools, workplaces” explained microbiologist and lead researcher Helena Rintala. “And as such we are constantly challenged by airborne microbes. It is important then to understand the exact nature of this exposure and to be able to understand how it affects our health.”

Indoor dust samples were taken in 2003 from two nursing homes located in small towns in central Finland, 100 km apart. Both buildings were similar in age, building frame, ventilation, use and rural location. Offices in the two buildings were sampled at different times during 1 year to obtain four samples per building, one for each season

By examining dust samples taken from hard surfaces such as tables and floors using a vacuum cleaner, Rintala and her colleagues found that Gram-positive bacteria dominated. This group includes Staphylococcus and Streptococcus species that belong to the normal bacteria in humans. Approximately five hundred bacterial species were estimated to be present in the dust, which is relatively easy to collect and reveals a good picture of the total microbial exposure in indoor environments. Although the diversity of the bacteria differed according to seasons, the difference between the buildings was greater than the variation observed throughout the year within a particular building.

“So far most of our information about microbes in indoor environments has concentrated on fungi. Our results show basic information on bacteria. Although our findings are significant, we do need more research to find out where the microbes are coming from for instance, “ concluded Rintala.

Source: BioMed Central”

Letting the sunshine in may kill dust-dwelling bacteria

Letting the sunshine in may kill dust-dwelling bacteria
by BioMed Central

https://phys.org/news/2018-10-sunshine-dust-dwelling-bacteria.html

“Allowing sunlight in through windows can kill bacteria that live in dust, according to a study published in the open access journal Microbiome.

Researchers at the University of Oregon found that in dark rooms 12% of bacteria on average were alive and able to reproduce (viable). In comparison only 6.8% of bacteria exposed to daylight and 6.1% of bacteria exposed to UV light were viable.

Dr. Fahimipour said: “Humans spend most of their time indoors, where exposure to dust particles that carry a variety of bacteria, including pathogens that can make us sick, is unavoidable. Therefore, it is important to understand how features of the buildings we occupy influence dust ecosystems and how this could affect our health.”

Dust kept in the dark contained organisms closely related to species associated with respiratory diseases, which were largely absent in dust exposed to daylight.

The authors found that a smaller proportion of human skin-derived bacteria and a larger proportion of outdoor air-derived bacteria lived in dust exposed to light that in than in dust not exposed to light. This may suggest that daylight causes the microbiome of indoor dust to more strongly resemble bacterial communities found outdoors.

The researchers made eleven identical climate-controlled miniature rooms that mimicked real buildings and seeded them with dust collected in residential homes. The authors applied one of three glazing treatments to the windows of the rooms, so that they transmitted visible, ultraviolet or no light. After 90 days, the authors collected dust from each environment and analysed the composition, abundance, and viability of the bacteria present.

Dr. Fahimipour said: “Our study supports a century-old folk wisdom, that daylight has the potential to kill microbes on dust particles, but we need more research to understand the underlying causes of shifts in the dust microbiome following light exposure. We hope that with further understanding, we could design access to daylight in buildings such as schools, offices, hospitals and homes in ways that reduce the risk of dust-borne infections.”

The authors caution that the miniature room environments used in the study were exposed to only a relatively narrow range of light dosages. Although the researchers selected light dosages similar to those found in most buildings, there are many architectural and geographical features that produce lower or higher dosages of light that may need additional study.”

________________________________

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

 

Drylands solution to climate change

An interesting article from The University of Derby (January 2020) says that new research offers a global drylands solution to climate change. Phys.org

Drylands - phys.org

“A new study published in the Journal for Geographical Research: Biogeosciences, led by a University of Derby academic, has shed new light on how microorganisms move through dryland landscapes attached to wind-blown dust and then alter the surfaces that they land on.

Drylands cover more than 40 percent of the global land area and are home to more than two billion people but are at growing risk of desertification, which makes the land unsuitable for grazing and agriculture, and causes hazards such as mobile sand dunes and dust storms.

The paper, “Surface Stability in Drylands is Influenced by Dispersal Strategy of Soil Bacteria,” was written with collaborators at Aberystwyth University and The Australian National University, and is part of a wider National Environment Research Council (NERC) funded project led by Loughborough University.

The team of researchers used a wind tunnel to analyse the dust eroded from the sandy soil on dry sand dunes in Australia. By comparing the microbes in the dust with the microbes in the source soil, researchers were able to identify which microbes contribute most to sticking soil together.

Dr. David Elliott, associate professor at the University of Derby explains: “In the world’s drylands, plants do not cover the soil surface as completely as they do in wetter regions leaving soils more exposed to weather and vulnerable to erosion by wind and water, which can lead to a reduction in soil quality.”

“Dryland soils that are not covered by plants do, however, usually have a thin covering of microbes that bind the soil together. These microbes are collectively called ‘biocrusts,” and they are important for stabilising dryland soils—meaning fewer dust storms, improved soil fertility, greater ability to hold onto rain water, and better opportunities for plants to establish.”

The researchers are now hoping to conduct further tests into how microbes disperse and interact with the landscape and evaluate the role of flooding in microbial dispersal to provide useful advice and possible interventions in managing the landscape.”

_______________________________________

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.