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File #: 12012-21    Version: 1 Name:
Type: Ordinance Status: Defeated
File created: 9/10/2021 In control: Chief Clerk
On agenda: 9/14/2021 Final action:
Title: An Ordinance of the County of Allegheny, Commonwealth of Pennsylvania, establishing a uniform Countywide system of mask requirements and exemptions for public and private gatherings.
Sponsors: Olivia Bennett, Bethany Hallam
Attachments: 1. 12012-21 Attach CDC - The Science of Masking.pdf
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An Ordinance of the County of Allegheny, Commonwealth of Pennsylvania, establishing a uniform Countywide system of mask requirements and exemptions for public and private gatherings.

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WHEREAS, the Centers for Disease Control (CDC) clearly and eloquently summarized many of the benefits of masking in their publication The Science of Masking to Control COVID-19, CDC, 11/16/20 (attached); and


WHEREAS, among the findings made by the CDC are the following:

· Infection is spread primarily through exposure to respiratory droplets exhaled by infected people when they breathe, talk, cough, sneeze, or sing.

a. Most of these droplets are <10 µm, often referred to as aerosols.

b. The amount of these fine droplets and particles increases with volume of speech (e.g., loud talking, shouting) and respiratory exertion (e.g., exercise).

· 40-45% of infected people are estimated to never develop symptoms, and among people who do develop symptomatic illness:

a. Transmission risk peaks in the days just before symptom onset (presymptomatic infection) and for a few days thereafter.

b. Accordingly, the number of infections transmitted peaks when virus levels peak.


· Most SARS-CoV-2 infections are spread by people without symptoms.

a. CDC and others estimate that more than 50% of all infections are transmitted from people who are not exhibiting symptoms.

b. This means, at least half of new infections come from people likely unaware they are infectious to others.


· Cloth masks provide source control, by containing exhaled droplets.

a. Cloth masks block most large (>20-30 µm) exhaled respiratory droplets.

b. Multi-layer cloth masks substantially block respiratory droplets <1-10 µm - Comprise the greatest fraction of exhaled respiratory droplets.

c. Reductions in exhaled aerosols overall when cloth masks are used are as high as 50-70%.

d. Some cloth masks perform on par with surgical masks for exhaled aerosols.


· Cloth masks also filter inhaled droplets...

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