Staff Reporter

2 Bedroom Home in El Paso – $209,900 |

March 21, 2022 by Staff Reporter

Pride of ownership in this beautiful ranch home. First floor master bedroom and bath with large walk-in closet. Living room – used as dining room with oak hardwood flooring. Kenmore washer/dryer in laundry room in basement but hook-ups on both levels. Convenient clothes chute. 2 rooms in basement used as bedrooms but no egress windows. High Efficiency Gas Heat/AC-2020; 30 Yr Architectural shingles 2021; Gas water heater 2020; Fully enclosed lot with vinyl picket and privacy fence; 12 x 22 screened porch with new remote controlled ceiling fan; 7ft 3-tier water fountain; Dual-fuel KitchenAid Range; Whisper Quiet Kenmore dishwasher; whole house vacuum; Generac back-up generator; SMART Chamberlain belt-driven garage door opener. Air-to-air exchanger and U.V light air sanitizer for highest indoor air quality. Built-in book case and 54″x46″ windows in 19 x 19 bedroom in basement(used as family room) with gas fireplace. Radon system installed in 2021.

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Originally Appeared Here

What causes mushrooms in your lawn? Four ways to get rid of pesky fungi

March 21, 2022 by Staff Reporter

Toadstools are a naturally occurring fungus that can crop up in clusters on your garden lawn and are rife at this time of year. While they may seem like a nuisance, mushrooms are not always a sign of an unhealthy lawn – in fact, they can signal quite the opposite. There are a few natural remedies for dealing with a shroom covered lawn, but first, you should identify the root cause.

What causes mushrooms in your lawn?

Mushrooms can be a sign of fungi rich soil which indicates a healthy, living lawn.

The fact that mushrooms can grow on your lawn indicates that your garden grass is packed with beneficial microbes which are hard at work.

According to experts at Rolawn, there are fungi in all turf, adding: “There are hundreds, possibly thousands of fungi, though few produce toadstools and mushrooms.

“Fungi are the most active of all micro-organisms in turf as they help degrade thatch and other organic debris and supply the turf with nutrients.”

READ MORE: Peace lilies: ‘Huge mistake’ houseplant owners can make

The fungi that do display themselves will present as mushrooms on your lawn – these produce the fruit or seed of the fungus.

On a new lawn, toadstools are more common because disruption to the turf can stimulate the fungi which eventually turns into these mushroom clusters.

Established lawns can grow visible mushrooms when the soil is filled with organic debris – either on or under the lawn.

Active spores can be carried into the garden by animals or wind which can also result in mushroom growth.

How to prevent mushrooms on lawns

You can prevent mushrooms from cropping up in large numbers using two methods – scarifying your lawn, or digging for debris.

Scarify to prevent mushrooms

According to Rolawn, you can reduce the amount of thatch by scarifying the lawn and then reducing the amount of fertiliser applied to the lawn.

Dig for debris

Do a thorough check for debris under your lawn to prevent organic matter from encouraging mushrooms to present on the surface of garden turf.

Use a pocket knife to dig underneath an existing clump of toadstools and seek out debris – if your mushrooms are growing from organic debris and not the lawn itself, replace the turf.

Are mushrooms on my lawn dangerous?

There is no fungicide treatment available in the UK because it is unnecessary to treat harmless fungi – in fact, it can even be beneficial to your lawn.

Of the 15,000 species of mushrooms in the UK, 99 percent are edible – but even experts have a hard time figuring out which ones are poisonous.

If your garden is regularly used by dogs or young children, it’s important to be cautious of all wild mushrooms which could be detrimental to the health of both humans and dogs if ingested.

A list of some poisonous mushrooms found in the UK include:

Fly agaric – the iconic fairy tale mushroom with the red spotted cap
Jewelled death cap – this mushroom has a yellow cap with white spots
Death cap – responsible for the most fatal mushroom poisonings in both people and pets
Autumn galerina – small brown and have a flatter cap than others and can often be found growing from decayed wood
Elf’s saddle – a dark ‘saddle’ shaped cap and a white stem

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Originally Appeared Here

Notable Women in Engineering: Kristi Linsmeier

March 21, 2022 by Staff Reporter

Category: BizTimes Milwaukee
Number of years working in your current industry: 28
Undergrad degree/university: BS Mathematics – UW Madison; BS Civil Engineering – UW Milw.

Kristi Linsmeier is environmental engineering group leader for Milwaukee-based The Sigma Group, where she directs a multi-discipline staff in assisting clients with regulatory compliance and permitting issues, indoor air quality assessments and process-related engineering tasks.

“Kristi’s diligent approach over the years has earned her a reputation as one of the state’s go-to individuals for regulatory risk management programs. She brings a highly disciplined and organized approach to her work and her clients, which is imperative given the high risk associated with regulatory compliance,” said Kenneth Kaszubowski, president of The Sigma Group.

Linsmeier has been with the 31-year-old firm for 28 years, starting out as an intern while attending the University of Wisconsin-Milwaukee as an engineering undergraduate. Recently, she was assigned the responsibility of integrating a merger between The Sigma Group and Rivers Bend Engineering in Sturtevant.

Linsmeier has led Sigma’s efforts to stay engaged during the COVID-19 pandemic, leading the “culture, connect, communicate” initiative, ensuring that staff stay aware and informed on business, client and internal activity while working remotely, Kaszubowski said.

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Originally Appeared Here

Working to provide pure drinking water in all households by 2024: Minister

March 21, 2022 by Staff Reporter

Working to provide pure drinking water in all households by 2024: Minister

February 20, 2022, 12:51 am

Bokaro, Feb 19 (UNI) Jharkhand’s Minister of Drinking Water and Sanitation Department Mithilesh Kumar Thakur has said that the government has set a target of providing pure drinking water to all the households of the state by the year 2024.
The department is working expeditiously in this direction by preparing an action plan and he himself is monitoring it regularly.

The minister, who arrived in Bokaro to attend a programme on Saturday while addressing the journalists in the Circuit House said that the agencies performing the works related to laying of water towers and pipes for drinking water supply, whose performance is slow and not satisfactory will be blacklisted. He said that any negligence in construction work will not be tolerated.

The minister said that the present government has provided pure drinking water facility to the homes of 11.50 lakh people so far in spite of various adverse circumstances during its tenure. Soon a review meeting will be held with the divisional level officials in which review will be done on various points/progress, Thakur said.

The minister said that the government is working in the interest of the state and is taking decisions after in-depth study, deliberation, contemplation on various demands of common people. He said that some parties are unnecessarily giving weight to some matters and this has nothing to do with the government.
UNI XC-AK RKM

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Originally Appeared Here

Toxic plants: ‘Harmful’ houseplants to avoid if you have cats and dogs – ‘some are lethal’

March 20, 2022 by Staff Reporter

Certain houseplants can be toxic to pets, according to experts at Flowercard, who recently researched the world’s most popular houseplants for 2022. This included Aloe Vera and Tulips, which can cause dogs and cats to become ill.

Flowercard explained: “Many common indoor plants can be harmful to pets, and while most won’t cause more than an upset stomach, some are lethal.”

Tulips, which can be found both inside and outside the home, can be toxic to dogs and cats.

The experts explained they contain glycosides, which is found in all flowers from the lily family.

Flowercard said: “The most toxic part of the plant is the bulb, and once eaten it can cause symptoms like vomiting and hypersalivation.”

READ MORE: Oven cleaning hacks: The 2-minute trick you probably didn’t know

Part of the rubber tree family, Flowercard said it can be toxic for animals if they eat it.

One other plant which pet owners should be mindful of is the ZZ plant.

Known for its wide, dark green leaves, it tolerates neglect and is a great houseplant for beginners.

However, Flowercard said: “The ZZ plant is mild to moderately toxic if ingested by pets. The toxins in the plant can cause symptoms including stomach aches and vomiting.”

Pet owners who have toxic plants should keep them out of reach at all times.

The company also shared the top low-maintenance plants that are the easiest to care for.

This included the Snake Plant, which is also toxic if ingested by pets.

Recent research by B Well CBD found that over 700 plants and flowers can be toxic for not only animals, but humans too.

This included Daffodils, the Spider Plant, Oleander and the Caladium houseplant.

Houseplant owners should always read the instructions before deciding on a placement for their plant.

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Originally Appeared Here

EPA, 건물 소유주 및 운영자가 실내 공기질을 개선하고 공중보건을 보호하게 돕고자 ‘건물 내 공기 청정 과제’ 발표.

March 20, 2022 by Staff Reporter

지침은 바이든 대통령의 국내 COVID-19 준비 계획을 완수할 예정.

March 17, 2022

2022년 3월 17일

워싱턴(2022년 3월 17일) – 금일, 3월 3일 발표된 바이든 대통령의 COVID-19 준비 계획의 일환으로 미국 환경 보호청(EPA)가 ‘건물 내 공기 청정 과제’를 발표했습니다. 해당 과제는 건물 소유주 및 운영자를 도와 공기 중 바이러스 및 기타 실내 오염물질에 노출될 위험을 줄이기 위해 행동에 나설 것을 촉구하고 이에 관한 지도 원칙 및 조치를 간명하게 나타낸 것입니다. 건물 내 공기 청정 과제는 빌딩 사용자들의 건강을 더욱 잘 보호하고 COVID-19가 전파되는 위험을 줄일 수 있게 도와줄 환기 및 실내 공기질 개선을 도와주는 다양한 권장사항 및 사용 가능한 자원을 강조합니다.

“공중보건을 보호한다는 말은 즉, 실내 공기질을 개선한다는 것입니다. 오늘 EPA는 COVID-19와 싸우면서 건강하고 지속가능한 방식으로 미국을 발전시킬 바이든 대통령의 계획을 완수하고 있습니다. 팬데믹 기간 동안, 건물 관리자와 시설 직원들은 위험을 줄이기 위해 실내 공기질을 개선하고 보호하며 건물 사용자들을 안전하고 건강하게 유지할 방법을 도입하는 업무의 최전선에 있었습니다. 그들의 노력에 매우 감사합니다.”라고 EPA 관리자 Michael S. Regan이 말했습니다. “건물 내 공기 청정 과제는 우리 모두가 더 쉽게 숨을 쉴 수 있게 도와주는 데 중요한 부분입니다.”

COVID-19와 같은 전염성 질병은 부유 입자 또는 에어로졸을 흡입하여 전파될 수 있습니다. 백신 접종과 같이 겹겹의 조치를 동시에 시행하는 것에 더해, 환기, 여과, 및 기타 입증된 공기 정화 전략을 개선하기 위한 조치는 오염 입자, 에어로졸 및 기타 오염물질에 노출될 위험을 줄이고 실내 공기질과 빌딩 사용자들의 건강을 향상시킬 수 있습니다.

건물 내 공기 청정 과제에서 윤곽이 드러난 주요 조치는 다음과 같습니다.

깨끗한 실내 공기 조치 계획 세우기
깨끗한 공기 환기 극대화
공기 여과 및 정화 개선, 및
지역 공동체 참여, 소통, 교육 수행

권장조치가 위험을 완전히 제거하지는 못하지만 위험을 줄일 것입니다. 건물 내 공기 청정 과제는 건물 소유주 및 운영자가 고를 수 있는 옵션과 모범 사례를 제시합니다. 특정 건물에 대한 조치의 최고 조합은 공간 및 위치에 따라 다릅니다. 해당 단계는 공중보건 지침, 건물 내에 누가 있고 얼마나 많은 사람이 있는지, 건물 내에서 일어나는 활동, 실외 공기질, 기후, 날씨 조건, 설치된 냉난방 및 환기(HVAC) 장비 및 기타 요소에 따라 달라집니다. 미국인 구조 계획 및 초당적 인프라법 기금은 공공시설의 환기 및 실내 공기질 개선에 보조 투자금으로서 사용될 수 있습니다.

EPA와 백악관 COVID-19 대응팀은 질병청, 에너지국 및 건물 내 건강한 실내 공기질을 촉진하는 역할을 맡은 기타 연방기관과 상의하여 건물 내 공기 청정 과제를 개발하였습니다. 금일 발표는 또한 건물 소유주 및 관리자가 건물 내 공기 청정 과제를 충족할 수 있게 도와줄 다양한 자원을 강조합니다. 본 문서는 스페인어, 중국어 간체, 중국어 번체, 베트남어, 한국어, 타갈로그어, 아랍어 및 러시아어로 제작됩니다.

건물 내 공기 청정 과제에 대한 더욱 자세한 정보는 다음을 참고하십시오. 건물 내 공기 청정 과제.

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Originally Appeared Here

Pennsylvania, Virginia in fight of their lives | Opinion

March 20, 2022 by Staff Reporter

If Gov. Tom Wolf’s administration gets its way in Commonwealth Court, Pennsylvania will join the Regional Greenhouse Gas Initiative (RGGI) in a matter of weeks.

The administration’s potential victory — a hollow quest to lower carbon emissions in Pennsylvania — will cost residents $2 billion in the next five years. How? According to the Department of Environmental Protection’s own budget projections, energy producers will spend an estimated $410 million each year buying credits at RGGI’s quarterly auctions meant to offset the emissions their facilities generate. Make no mistake, this is a carbon tax, which means utilities will increase customers’ rates to recoup their added costs.

So now, on top of record-breaking inflation, skyrocketing gas prices and supply chain nightmares, Pennsylvanians will pay up to 25% more to keep the lights on and stay warm during winter. And that clean air RGGI promises to deliver? It won’t exist either, since nothing can prevent carbon dioxide and other air pollutants emitted from power plants in Ohio or West Virginia from drifting across state lines. Even the most optimistic projections today show a CO2 reduction of less than 1% by 2030.

Virginia recognizes the abject failure of RGGI to achieve any of its stated goals and wasted no time reversing course on the legislature’s shortsighted decision to join the program two years ago. Despite wailing and gnashing of teeth from the green lobby, Virginia Gov. Glenn Youngkin’s executive action — and corresponding legislative action — will protect the state’s most vulnerable from an unconscionable spike in utility costs at a time when global conflict and economic uncertainty threaten us all.

If only this administration felt a similar allegiance to the 13 million people it represents. If only they supported energy policy that prioritized independence and valued the plentiful resource right beneath their feet.

Instead, the proposal is to leave Pennsylvania’s environmental and economic destiny to the whims of elected officials in New York and New Jersey. In each auction, the 11 states compete for a finite number of credits allowed under the regional cap. That number is based on a collective goal to reduce emissions 30% by 2030.

That means New England states — Maine, Vermont, New Hampshire, Rhode Island and Connecticut — joined New York, Delaware, New Jersey, Maryland and Virginia in setting an “acceptable” level of power sector carbon pollution. None of those states boast a robust energy industry, but rather rely on foreign gas and oil imports to meet demand.

So Pennsylvania, the number two natural gas producer in the country and the nation’s top power exporter, should set its environmental policies based on Vermont’s or Maine’s or New York’s standards?

This isn’t the first time the administration listened to liberal idealogues from states that bear little resemblance to our own. For example, the administration sat idly by while other mid-Atlantic states in the Delaware River Basin Commission made rules that restricted Pennsylvania’s energy development. Pennsylvania routinely adopts a “regional” approach to complex issues without recognizing the unique challenges we face or the inherent economic power we alone hold. RGGI is a prime example.

In Virginia, frustrated lawmakers and the environmental groups that bankroll them will inevitably challenge Youngkin’s executive order in the courts. The Southern Environmental Law Center even had the audacity to tell Forbes that the state’s RGGI participation “cannot be undone by a simple pen stroke” since only the General Assembly “gets to decide laws in Virginia.”

It’s strange how their counterparts a few hundred miles north claim the exact opposite — the state’s Air Pollution Control Act somehow gives our governor unilateral power to enact a tax on the power sector without considering any legislative input. This is not how the other RGGI states decided to join either.

The administration will dance around this fact, like it did during DEP’s budget hearing before the Senate Appropriations Committee earlier this month. But the truth still remains — 162 out of 253 elected officials in Pennsylvania oppose joining RGGI because it will raise electricity bills, send thousands of jobs out of state and do nothing to improve air quality.

Unexpected Republican victories in Virginia means lawmakers there could codify the RGGI exit through statute. Pennsylvania won’t be that lucky. Our divided government means only a veto override – or a successful legal challenge — can prevent us from barreling head-first into this disastrous carbon tax scheme.

State Sen. Gene Yaw represents the 23rd District.

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Originally Appeared Here

No water is safe from pollution

March 20, 2022 by Staff Reporter

By Cuthbert Mavheko

Every year, March 22 is set aside to commemorate World Water Day. On this day, which was first observed in 1993, the world’s attention is focused on the earth’s most important resource water.

Water is a basic human right, every human being in the world must have access to safe, clean drinking water and sanitation for them to live a healthy and dignified life.

In respect of the right to water, section 77(a) of the Constitution, states that: “Every person has the right to safe, clean and potable water… and the State must take reasonable legislative and other measures, within the limits of the resources available to it to ensure the progressive realisation of this goal.’’

In light of this, it is incumbent upon central government and local authorities to ensure that every man, woman and child in the country has safe, clean and potable water. The bitter truth, however, is that local authorities in the country’s urban areas have ignominiously failed to provide safe, clean water and proper sanitation services to enhance the health and social wellbeing of the urban population. Sad to say, this has often exposed urban residents to diseases like diarrhoea.

The following illustrations buttress this pertinent observation: In June 2020, there was a diarrhoea outbreak in Luveve, Bulawayo which reportedly claimed the lives of 13 people and infected nearly 2 000 others. It is widely believed that the diarrhoea outbreak was caused by raw sewage, which contaminated drinking water. In October the same year, about 100 people, mostly children, were treated for running tummies in Mzilikazi, Bulawayo and surrounding suburbs after drinking contaminated water.

The local authority last year recorded 40 cases of the diarrhoea outbreak, caused by contaminated water, in Emganwini suburb. Such outbreaks have, over the past few years, also been recorded in Harare, Gweru, Kadoma and other cities.

Without claiming the expertise or the competence of a qualified environmental scientist for an exhaustive and illuminating analysis of such a wide and complex subject as water pollution, one would, however, not be totally off the mark to conjecture that water pollution is not unique to Zimbabwe, but is actually a worldwide phenomenon.

The World Health Organisation (WHO) designated the 1980s as International Drinking Water Supply and Sanitation Decade. Its goal was to bring about ‘’safe drinking water and adequate sanitation by 1990 for billions of people in developing countries’’.

However, a study published in the magazine Environmental Health a few years ago, says water in many developing countries is not pure and clean as it has been contaminated by synthetic chemicals emanating from the dumping of chemical-laden matter into lakes, rivers, streams and dams.

Seeing that pollution has affected surface water, more and more nations are reportedly turning to underground resrves, which they believe can be depended on to provide pure and clean water.

This year’s World Water Day theme: Groundwater draws the world’s attention to this hidden water resource that has always been critically important, but has not been fully-recognised and utilised in sustainable development policy-making.

The study published in the Environmental Health magazine further states that many people in both developed and developing nations are now getting their household water from aquifers. For those not in the know, aquifers are vast networks and bodies of water under the crust of the earth, which flow slowly like underground rivers. This underground water comes from surface water, which soaks down through the soil and rock formations, finally emptying into the oceans.

This network of underground water is said to be quite extensive. According to some geological studies, some of this underground water extends as much as 4,8km below the earth’s surface. In the top 0,8km of the earth’s crust alone, it is estimated that there is more than 30 times the amount of fresh water than what is contained in all the lakes, rivers, streams and inland seas on the surface put together.

This vast reservoir of underground water was long assumed to be safe from contamination, since the water is purified as it passes through layers of soil. However, it has been confirmed that underground water is not immune from pollution. Chemicals from agriculture have reached and contaminated this water. So has infiltration from toxic waste from industrial waste repositories, at times raw sewage can leak out of aging pipes and befoul ground water.

It is no hidden secret that in some countries, enormous quantities of industrial wastes are poured into lakes, rivers and streams. This toxic waste soaks into the ground, thereby polluting aquifers. It has been estimated in scientific studies that up to half of all underground water is contaminated by either disease-producing bacteria or toxic industrial waste.

Researchers have found that pollution of underground water is also caused by such varied “non-industrial” sources as leaks from underground diesel/petrol tanks, lead and cadmium dissolved from water pipes as well as garbage that is dumped haphazardly.

To add insult to injury, rain water can no longer be relied upon as pure and clean. Researchers in the United States say tonnes of nitrogen oxides and sulphur-dioxides spewed into the air by emissions from automobiles, coal-burning power plants and other industrial sources do not stay in the air. Instead, they come down as dry acidic powder or mix with moisture in the atmosphere and come down in rain, snow and fog as nitric or sulphuric acid.

The researchers further state that acid rain or acid fog is responsible for a wide variety of harmful effects that include dead lakes, decimated forests, lifeless soil, aggravated respiratory conditions and other health problems.

Cuthbert Mavheko is a freelance journalist based in Bulawayo. He writes here in his personal capacity.

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Originally Appeared Here

Lidl and B&Q sell rare plant worth a fortune – Britons make thousands single leaf

March 20, 2022 by Staff Reporter

These plants, which are sold in most supermarkets and garden centres, see their value increase after a naturally occurring variation. How can you spot it?

Many people don’t know some common houseplants can be extremely valuable as these variations are often mistaken for a disease.

Some shops even reduce the plant’s price after it happens.

Britons could make thousands by selling just a small part of the plant, a single leaf of the stem.

These plants can be found in shops such as Lidl and B&Q.

READ MORE: Oven cleaning hacks: The 2-minute trick you probably didn’t know

Pink Princess Philodendron

Very similar to the White Knight and White Princess, the Pink Princess Philodendronbut has pink variegation instead.

It can take a while to show, but if people spot the pink stains on the leaves, they could be selling it for thousands.

Some of these plants are currently selling on Etsy for £2,228 or £200 for a single leaf.

Monstera Obliqua

This may be one of the rarest houseplants but is still present in many British homes.

The Monstera Obliqua’s leaves could be easily mistaken for pest damage.

However, a single leaf of the most sought-after plant is selling on Etsy for £1,590 and on eBay for £1,250.

Over on Facebook Marketplace, a small plant goes for £1,000.

Additional reporting Lea Dzifa Seeberg

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Originally Appeared Here

Acidity of expiratory aerosols influences infectivity of SARS-CoV-2

March 20, 2022 by Staff Reporter

Enveloped viruses can be inactivated by exposure to acids, such as within aerosols in the atmosphere. A new study posted to the medRxiv* preprint server provides insight on the potentially significant impact of aerosol pH on the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Study: Acidity of Expiratory Aerosols Controls the Infectivity of Airborne Influenza Virus And SARS-Cov-2. Image Credit: Aranami / Shutterstock.com

Introduction

Respiratory viral infections are among the most common human illnesses. For example, the influenza virus is responsible for about 400,000 deaths each year worldwide, while the ongoing coronavirus disease 2019 (COVID-19) pandemic has caused over six million deaths in the two years since its inception. Virus transmission is therefore a prime target of prevention strategies and other interventions intended to contain outbreaks.

Many experts have indicated that respiratory aerosols formed during expiration are important in the spread of both influenza and SARS-CoV-2. Thus, the rapid inactivation of these pathogens is an important step in restricting their transmission.

However, beyond temperature and humidity, there is limited data available on the relationship between aerosol acidity and the inactivation of these viruses. The pH of the aerosol depends both on the composition of the particles in the aerosol and of the ambient air.

Particles in outdoor air are highly acidic, with the pH plunging as low as -1. The more volatile the acid or base in the aerosol, such as nitric acid and ammonia, the greater the effect on the pH, as these chemicals rapidly condense on aerosol particles. Notably, the presence of strong organic acids like vinegar or formic acid is of minor significance with respect to aerosol pH.

Indoors, these volatile acids are at lower concentrations, as they condense rapidly on both particles and surfaces. Nitric acid and ammonia levels in indoor air are therefore 0.1-0.5 and three to 30 times that in outdoor air, while organic acids are also elevated.

The use of humidification, ventilation, and air conditioning (HVAC) systems is another major factor that can impact air composition. Expiratory aerosols are rich in ammonia and carbon dioxide, along with a considerable amount of aerosol particles including ions, proteins, and surfactants.

The current study explores how aerosol acidity is related to the inactivation of the influenza A virus (IAV), SARS-CoV-2, and the seasonal human coronavirus HCoV-229E (229E) indoors.

Study findings

Inactivation times were found to decrease from a matter of days to seconds, covering five orders of magnitude, as the pH was reduced from 6 to 4. The concentration of the synthetic lung fluid (SLF) in which the viruses were immersed in one set of samples did affect the inactivation time, with the extrapolated data showing an increase in inactivation time by up to a factor of 56 when SLF was enriched 18 times.

Concentrated SLF was thus protective against IAV inactivation, especially around the pH optimal for IAV fusion, but less so against the coronaviruses, which remained stable down to pH 3. Beyond this point, when inactivation required 24 hours at a pH of 2, the inactivation times declined rapidly to less than ten seconds for SARS-CoV-2. However, the minimum inactivation time remained above two hours for HCoV-229E.

This difference is hypothesized to be due to the difference in the way these viruses enter the host cells. IAV uses a hemagglutinin antigen, which changes conformation during endosomal entry and relies on acidification. The irreversible nature of this conformational shift means that once it occurs outside the cell at an acidic pH, the virus is no longer able to bind to the host cell receptor, thereby leading to its inactivation.

Comparatively, the spike protein of coronaviruses, which is responsible for cell entry, does not undergo fusion-mediating conformational shifts due to acidification but rather because of host protease activity. Still, the two coronaviruses here showed different activity patterns at a pH below 3.

When the individual micron-sized SLF and nasal mucus particles were studied for their thermodynamic behavioral and kinetic properties, differences were found in the salt composition, which affects deliquescence, and water uptake or loss. The differences in water loss at each stage may be due to variations in the mode of salt crystal formation within and at the surface of the droplet.

The limit on the diffusion of ions in the SLF and nasal mucosa differs from the universally fast diffusion of water in both media. The latter rules out the formation of semisolid phases that would prevent diffusion, as suggested by some earlier studies.

The scientists combined virus properties with aerosol thermodynamics and kinetics data to build a biophysical model called the Respiratory Aerosol Model (ResAM). This was intended to simulate changes in the composition and pH of the expiratory particle during expiration, and determine how this changed viral infectivity.

When considering changes in relative humidity with the ion and water diffusivities, the model was able to predict the mass fraction of solutes among both deliquescence and efflorescence. This accuracy is dependent on the inclusion of kinetic effects.

As the pH reduces, a particle with a diameter of two microns will undergo rapid water loss, along with the concentration of organic compounds and salts, until the salt sodium chloride undergoes effloresces. Nitric acid in indoor air quickly enters the particle, thus causing a sharp drop in its pH.

The room air, which has a pH of about 6.6 due to high carbon dioxide and ammonia levels, accepts nitric acid into its aerosol particles. This reduces the pH to 5 within seconds, thereby pulling the basic ammonia into the particle. The pH was found to further decline to 3.7 slowly as more nitric acid is absorbed into the particle.

If only carbon dioxide is measured, the pH of the exhaled particle would be expected to rise, which emphasizes the need to measure trace gases in determining the actual pH of indoor air aerosol particles. In such acidic conditions of expiratory aerosol, IAV would be inactivated within two minutes; however, the coronaviruses remain infectious.

Particle size also correlates positively with inactivation times. This is because the larger the particle, the longer the time needed to reach an acidic pH as a result of the need for ions and molecules to diffuse over a longer pathway in air and liquid phases. Within 2 minutes, 99% of IAV particles below a radius of one micron, which is typical of expiratory particles, undergo inactivation, whereas those larger than one millimeter remain active for up to 5 days.

Time required for 99% titer reduction of influenza A virus (IAV), SARS-CoV-2 and human coronavirus HCoV-229E measured in various bulk media (> 10 µl) at 22°C. Data points represent inactivation times in aqueous citric acid/Na2HPO4 buffer, synthetic lung fluid (SLF) or nasal mucus with pH between 7.4 and 2. SLF concentrations correspond to water activity aw = 0.994 (1 × SLF; squares), aw = 0.97 (5 × SLF; stars) and aw = 0.8 (18 × SLF; triangles); buffer (circles) and nasal mucus (diamonds) correspond to aw ∼ 0.99. Each experimental condition was tested in replicate with error bars indicating 95% confidence intervals. While IAV displays a pronounced reduction in infectivity around pH 5, SARS-CoV-2 develops a similar reduction only close to pH 2, and HCoV-229E is largely pH-insensitive. Solid lines are arctan fits to SLF data with aw = 0.994 (blue: IAV; red: SARS-CoV-2; black: HCoV-229E). The dashed line is an arctan fit to the SLF data with aw = 0.80. The dotted line is an extrapolation to aw = 0.5 (24 × SLF). Upward arrows indicate an insignificant change in titer over the course of the experiment, and downward arrows indicate inactivation below the level of detection at all measured times. The fitted curves below pH 2 (grey shaded area) are extrapolated with high uncertainty. Examples of measured inactivation curves are shown in Fig. S1. The arctan fit equations, which are also used for the model simulations, are given by Eqns. S28, S29, and S30.

Thus, a rise in particle size is closely proportional to IAV inactivation time when indoor conditions are considered, while at all sizes, SARS-CoV-2 remains active for much longer. With acidification of indoor air, both IAV and SARS-CoV-2 are much more quickly inactivated, if only the acidic molecules of the aerosol are volatile enough that they quickly pass from being in the gaseous to condensed phase. Additionally, gaseous acid molecules must be strong enough to compensate for the buffering effect of particles in the particle matrix.

The introduction of larger particles caused the pH to decline rapidly and significantly as compared to when volatile organic acids like acetic acid were introduced into the cells. SARS-CoV-2 inactivation occurred four to five orders faster in this air as compared to typical room air.

Purifying air reduces trace gases, such that strong organic acids that are already two times lower indoors as compared to outdoors drop in concentration by 10-80 times. This causes the aerosol pH to rise above that of indoor air, thereby becoming neutral or even a little basic.

As a result, air purification is expected to enhance virus persistence, especially for IAV.”

Conclusions

The results of the current study were demonstrated by modeling. The addition of 50 parts per billion (ppb) of nitric acid fails to improve the inactivation time of HCoV-229E but may reduce transmission risks of IAV and SARS-CoV-2 by 20 and 800 times.

Conversely, increasing ventilation from two air changes per hour to ten per hour reduces the concentration of SARS-CoV-2 by five times, while it does not affect the already rapid inactivation of IAV.

Normal air purification systems reduce important trace gases like nitric acid; however, this is more important when the air filters contain activated carbon, which enhances acid removal. This could increase the risk of IAV spread significantly in such buildings as compared to those that use outdoor air without filtration.

Here we demonstrate that a significant reduction in transmission risk can be achieved by air enrichment with HNO3 levels that correspond to less than 10% of the legal exposure thresholds.”

While these fall below human exposure thresholds, their effects on the microbiome and immune response of the respiratory tract remain to be known in future studies, as well as the effects of other respiratory matrices.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

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