屋外も増えるマスク着用義務付け、でもオフィスでは？

【パリＡＦＰ＝時事】新型コロナウイルスの感染拡大が再燃する中、夏の街頭やビーチにあふれる人々を見て警戒した欧州諸国の一部では、公共の場でのマスク着用を屋内だけでなく、屋外でも義務付けるようになっている。（写真は資料写真）
　最近になって欧州の複数の国の政府は、マスク着用の勧告を強化している。フランスとベルギーでは、マスク着用規則の適用範囲に屋外も含むようになった。
　しかし専門家らは、そうした対策は的外れではないかと疑問を呈している。集団感染の多くがオフィスなど、マスクに関する規則が明確でない職場の密室で起きているからだ。一方で、屋外での感染リスクが高いという証拠はほぼ存在しない。
　コンサルティング会社パブリック・ヘルス・エクスパタイズのマルタン・ブラシエ氏は「屋外では空気と混ざるので、ウイルス濃度は感染が起きるほど高くない」と指摘する。
　ブラシエ氏は屋外でのマスク着用義務化について、感染リスクがはるかに高い屋内に人々を押し込めかねない「心理的賭け」だと称した。
　同氏によるとむしろ重視すべきなのは、ソーシャル・ディスタンシング（対人距離の確保）を基本とした「古い」勧告に従ったままの企業だ。なぜなら以前の勧告は、新型コロナウイルスが空気中に数時間残留する可能性があるという最新研究を考慮に入れていないからだ。

■オフィスでのリスク
　世界保健機関（ＷＨＯ）は先月初め、新型コロナウイルスの空気感染について新しい証拠の見直しを行っていると発表した。新型コロナウイルスは人との間に空けるべき物理的距離として推奨されている２メートルをはるかに超えて移動することができるとする、国際的な科学者グループの結論を受けてのことだ。
　多くの国では現在、店や電車、バスなど閉鎖された一定の公共空間でマスクの着用を義務付けている。だがオフィス向けの指針は、それほど厳密ではないことが多い。
　英バーミンガム大学応用衛生研究所のＫＫ・チェン所長は、マスク着用が店舗で義務付けられていながら、ほとんどの職場ではそうなっていないことについて、「合理的な説明」がないと指摘する。
　米疾病対策センター（ＣＤＣ）が今月発表した研究で言及した９７人のクラスター（感染者集団）は、その大半が韓国の首都ソウルのコールセンターの従業員だった。このコールセンターでは１１階にあるオフィスの従業員２１６人のうち、９４人が検査で陽性と判定された。陽性率は４３．５％だ。研究者らによると、感染者のほとんどはビルの同じ側で働いていた。

■奨励される在宅勤務
　仏保健省によると、新型ウイルスのクラスターの４９％は病院を含めた「職場」で発生している。
　また、仏ピティエサルペトリエール大学病院の感染症科長、エリック・コーメ医師によると、これらクラスターの約２０％は企業で発生している。
　コーメ氏は企業に対し、学校の夏休みが明けた後も可能な限り、従業員の在宅勤務を継続するよう呼び掛けている。
　フランスでは７月下旬から公共の閉鎖空間でのマスク着用を義務付けているが、オフィスでの指針は個々の雇用者の判断に任せている。これを批判する医療専門家のグループが、１５日の日刊紙リベラシオンに公開書簡を掲載した。
　この専門家グループは、閉じた部屋の空気中に蓄積するウイルスを「たばこの煙」になぞらえている。「長時間の暴露であれ、ウイルスを排出する人が多かった場合であれ、ウイルスが空気中にたまればたまるほど感染リスクは高まる」 【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2020/08/25-12:53）

Faced with an upsurge in coronavirus cases and alarm over images of summer crowds packing onto streets and beaches, some European governments have mandated masks even in open-air public places.
But with many virus clusters sprouting behind closed doors in offices and other workplaces where face covering rules are less clear, experts have questioned if policies are focusing on the wrong target.
In recent days several European countries have toughened their advice on masks, with France and Belgium widening their regulations to include certain outdoor settings.
Brussels residents are now required to wear masks in all public spaces, and all spaces to which the public has access.
In France, dozens of towns and cities -- including Paris -- have made face coverings mandatory in markets and busy streets.
The country's Ministry of Health has said it was a gesture of common sense to wear one in crowded public places, while the head of France's science council, Jean-Francois Delfraissy, has said they should be essential on packed streets and at seaside resorts.
However with little evidence that there is a high risk of transmission in outdoor settings, some experts have questioned whether the measures are misplaced.
Outside, there is such a mixing of air that you do not have a sufficient viral concentration to be infectious, said Martin Blachier, of the consulting company Public Health Expertise.
He called the measure a psychological gamble that could push people to gather indoors, where he said the risk of contamination is far higher.
Blachier said the focus should instead be on companies, where the current advice is obsolete because it is based on social distancing, without taking into account new research suggesting the virus can linger in the air for several hours.
- 'Inviting trouble' -
The World Health Organization said in early July that it was reviewing emerging evidence of airborne transmission, after an international group of scientists concluded the virus could travel far beyond two metres (6.5 feet) -- the measurement recommended in physical distancing guidelines.
Its announcement was part of a transformation in official assessments of the utility of masks in slowing the spread of the virus.
Initially authorities, including the WHO, were unconvinced of the effectiveness of face coverings and wary of encouraging the public to use them when health workers were chronically short of protection.
Early in the pandemic, it was considered unlikely that COVID-19 could be transmitted by microdroplets expelled by people when they speak and breathe.
But scientific opinion has since shifted and, along with increased understanding of asymptomatic and pre-symptomatic spread, this has strengthened the argument for universal mask wearing.
Many countries now require people to wear face coverings in certain enclosed public places, like shops, trains and buses.
But offices are often given less stringent guidelines.
KK Cheng, who runs the Institute of Applied Health Research at Britain's University of Birmingham, said there was no rational explanation for why masks were compulsory in shops but not in most workplaces.
He raised particular concerns over environments like call centres, where there are large numbers of people all speaking quite loudly together.
If you have a large number of people working in an office like that then you are just inviting trouble, he added.
A study published this month by the United States Centers for Disease Control described a contagion cluster of 97 people, mostly workers at a call centre in the South Korean capital Seoul.
Of the 216 employees in the 11th floor office, 94 people tested positive -- an attack rate of 43.5 percent -- and most of those infected worked on the same side of the building, researchers said.
- Encourage remote working -
According to France's Ministry of Health, 49 percent of the virus clusters recorded are in the workplace, including in hospitals.
Health expert Eric Caumes, head of the infectious diseases department at the Pitie Salpetriere hospital in Paris, said around 20 percent of these groups of infections were in companies.
He called for firms where possible to continue to allow staff to work at home after the school holidays.
We will have to continue to work from home, to organise ourselves differently to avoid multiplying clusters in private companies, he told Franceinfo radio on Thursday.
France has mandated face coverings in enclosed public spaces since late July, but left guidance on offices more at the discretion of employers.
This was criticised in an open letter by a group of medical experts published in the newspaper Liberation on Friday, who compared the virus accumulating in the air of enclosed rooms to cigarette smoke.
And the more the virus accumulates in the air -- either because of a long exposure time or because of a large number of excretors -- the more we risk contamination, they said.
They called for the government to make masks compulsory in all confined spaces, offices and classrooms and to unambiguously encourage remote working.
KK Cheng acknowledged that the face coverings could be uncomfortable and very hard for some people to wear.
But he said it was a necessary measure to help slow the virus, which has infected more than 20 million people and killed more than 750,000 globally since emerging late last year.
It's so serious that I think that the discomfort of wearing a mask is something worth bearing, he said.
A lot less comfortable is lockdowns, people dying.