Plexiglass shields are everywhere, but it's not clear how much they help

Plexiglass shields have become ubiquitous at offices, grocery stores and restaurants across the country in the coronavirus age. They were even installed on t...

Posted: Oct 13, 2020 1:28 PM
Updated: Oct 14, 2020 8:15 AM

Plexiglass shields have become ubiquitous at offices, grocery stores and restaurants across the country in the coronavirus age. They were even installed on the vice presidential debate stage last week.

Given that they're just about everywhere, you may wonder how effective they actually are.

Businesses and workplaces have pointed to plexiglass dividers as one tool they are using to keep people safe against the spread of the virus. But it's important to know there's little data to support their effectiveness, and even if there were, the barriers have their limits, according to epidemiologists and aerosol scientists, who study airborne transmission of the virus.

The Centers for Disease Control and Prevention (CDC) has offered guidance to workplaces to 'install physical barriers, such as clear plastic sneeze guards, where feasible' as a way to 'reduce exposure to hazards,' and the Labor Department's Occupational Safety and Health Administration (OSHA) has issued similar guidance.

That's because the plexiglass shields can in theory protect workers against large respiratory droplets that spread if someone sneezes or coughs next to them, say epidemiologists, environmental engineers and aerosol scientists. Coronavirus is thought to spread from person to person 'mainly through respiratory droplets produced when an infected person coughs, sneezes or talks,' according to the CDC.

But those benefits haven't been proven, according to Wafaa El-Sadr, professor of epidemiology and medicine at Columbia University. She says there have not been any studies that examined how effective plexiglass barriers are at blocking large droplets.

Moreover, the bigger problem is that even if they do, that's not the only way that the coronavirus spreads. Last week, the CDC released new guidelines saying that the coronavirus can spread through aerosols — tiny particles containing the virus that float in the air and can travel beyond six feet — that are released when people breathe, talk or sneeze.

Most droplets people release when they talk or breathe are in a 'size range that will flow past the barrier,' said Pratim Biswas, an aerosol scientist at Washington University in St. Louis.

The dividers 'do not address all possible modes of transmission, such as aerosol transmission, or fully protect anyone from Covid-19,' the University of Washington's Environmental Health and Safety Department said in a July review of the benefits and limitations of plexiglass barriers at campus facilities.

There's also another problem in some cases: the size of the barriers. Marissa Baker, an assistant professor at the University of Washington, has been conducting a separate study of coronavirus safety measures at nine grocery stores in Seattle and seven in Portland, Oregon, each month since May.

She has observed that plexiglass shields at cash registers and self-checkout stations are often too small to even prevent droplet transmission between customers and workers.

'Some are smaller and don't even cover the nose of a tall individual,' she said. 'The airborne particles are going to be able to get anywhere, regardless of the barriers.'

Restaurants and retail industry trade groups say they view the barriers as one potential way to combat the spread of Covid-19, in addition to other measures.

'We know so much more now, and we follow the scientific data to guide our decisions. Based on the recommendations by public health authorities, it would be important to look at layered controls in any environment,' a spokesperson for FMI, a trade group for the grocery industry, said in an email. Mask wearing and maintaining social distancing 'are still two effective means to mitigate risk of contracting the virus.'

The National Restaurant Association said in a statement that plexiglass shields and barriers are a tool that 'when combined with other best practices -- like face coverings, appropriate social distancing, and handwashing -- provide an additional level of safety.'

Depending on where you work or where you visit, such measures may be less than realistic, though. For instance, cashiers and waiters can't do their job without being in close proximity to customers.

That's why upgrading ventilation systems is important to reduce the virus' airborne spread in indoor settings, experts say.

Indiana Coronavirus Cases

Data is updated nightly.

Cases: 300913

Reported Deaths: 5332
CountyCasesDeaths
Marion41330845
Lake26364448
Allen17299290
Elkhart16665212
St. Joseph16319220
Hamilton12459164
Vanderburgh9428112
Tippecanoe826727
Porter791279
Johnson6139164
Hendricks5807154
Vigo574474
Monroe525247
Clark495374
Delaware4789103
Madison4760119
LaPorte446894
Kosciusko446139
Howard325575
Warrick316072
Floyd306177
Bartholomew303262
Wayne295261
Cass293431
Marshall289944
Grant258747
Noble246846
Hancock243749
Henry237136
Boone235154
Dubois230430
Dearborn208829
Jackson206033
Morgan200643
Knox178017
Gibson177022
Clinton174920
Shelby174554
Lawrence171646
DeKalb171229
Adams165219
Miami155114
Wabash153018
Daviess152243
Fayette145233
Steuben141113
Jasper138311
Harrison137624
LaGrange136629
Montgomery131226
Whitley129910
Ripley123714
Decatur123542
Huntington122310
Posey118913
Putnam118326
Wells118327
Randolph117819
White117421
Clay115621
Jefferson114214
Greene100253
Scott99818
Jay95012
Starke89221
Sullivan86615
Fulton81117
Perry80921
Jennings80514
Spencer8047
Fountain7378
Washington7176
Carroll66813
Franklin65925
Orange65728
Vermillion5832
Owen5816
Parke5416
Newton54012
Tipton53726
Rush5216
Blackford51211
Pike50218
Pulaski36810
Martin3485
Brown3263
Benton3251
Crawford2781
Union2621
Switzerland2473
Warren2352
Ohio2257
Unassigned0265

Ohio Coronavirus Cases

Data is updated nightly.

Cases: 363304

Reported Deaths: 6020
CountyCasesDeaths
Franklin49267665
Cuyahoga35214736
Hamilton29462371
Montgomery19636225
Butler14472144
Lucas14033409
Summit12962310
Stark8529197
Warren798975
Mahoning7068299
Lake662766
Lorain623697
Clermont563946
Delaware540335
Licking535875
Fairfield523763
Trumbull5159144
Greene510563
Clark501064
Allen460685
Marion457751
Wood4394107
Medina428654
Miami416465
Pickaway396448
Columbiana339597
Portage334471
Tuscarawas317557
Wayne314993
Richland306732
Mercer284737
Ross239259
Hancock232736
Muskingum231910
Auglaize223230
Putnam221449
Erie217165
Darke217058
Ashtabula215753
Geauga197351
Scioto193615
Union18658
Lawrence185436
Shelby184815
Athens18454
Seneca173118
Belmont158529
Madison156218
Sandusky152327
Preble148421
Huron147518
Defiance137921
Holmes137739
Logan123613
Knox122518
Fulton122025
Crawford119116
Ottawa118930
Washington116427
Clinton103414
Ashland102722
Williams10238
Jefferson10124
Highland99517
Henry98422
Brown9644
Champaign9345
Jackson90312
Van Wert8976
Fayette89217
Hardin86118
Morrow8552
Guernsey83313
Coshocton81413
Perry77012
Adams75012
Pike7261
Wyandot70516
Gallia70413
Paulding62710
Hocking61011
Noble59722
Carroll44310
Meigs37612
Monroe31021
Morgan2395
Vinton2105
Harrison1913
Unassigned00
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