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Analysis: Most schools meet district ventilation standards. Experts say that may not be enough


A Chalkbeat analysis found the ventilation in most schools meets the district’s air circulation standards — but only because so few students are returning and the standard is minimal.

Emma Lee / WHYY

With Philadelphia’s youngest students scheduled to return to school in a few weeks, the ventilation in most schools meets the district’s air circulation standards — but only because so few students are returning and the standard is minimal, a Chalkbeat analysis found. 

The air flow in about 94% of elementary schools is adequate by the district’s measures, according to hundreds of ventilation reports reviewed by Chalkbeat. But that is because fewer than 10% of the district’s enrolled students are returning and the district’s ventilation standards, which have long been acceptable for schools, are lower than that required to prevent the spread of airborne diseases.

Ensuring that the city’s aging buildings can be ventilated to help reduce the spread of the coronavirus has become one of the most urgent tasks facing district officials ahead of students returning to classrooms on Feb. 22. In recent months, many parents, teachers, and union officials have cited ventilation issues as a reason why schools couldn’t safely reopen for in-person learning. 

Declaring that it has “concerns” about ventilation in many schools, the Philadelphia Federation of Teachers requested the intervention of a third party through the city Department of Labor to determine whether it is safe to return. About 2,000 teachers for grades prekindergarten through second grade have been told to return Monday. But on Friday, Jerry Jordan, president of the PFT, told teachers not to come back to buildings because of safety concerns. He said they should continue to work remotely. 

Jerry Roseman, the union’s environmental scientist, said that simply looking at the numbers “is not good enough.” For instance, some of the schools may have mechanical ventilation systems that were shut down due to asbestos issues, and he said it isn’t always clear from the reports whether the issues have been resolved or if the school is relying on another ventilation method, such as window fans. 

“The reporting from the district needs to be more detailed to be able to make an independent assessment of safety,” he said. 

On ventilation, a binding agreement between the district and the union says the district must complete an “air balancer certification” for each space that will be occupied and identify the maximum occupancy based on “the available CFM or fresh air flow.” CFM stands for cubic feet per minute. The standard is 15 CFM per person.  

Experts on industrial hygiene explained that the standards, those sanctioned by The American Society of Heating, Refrigerating and Air-Conditioning Engineers, are meant only to maintain tolerable aesthetic conditions when people gather in a confined space. 

Chalkbeat’s analysis is based on the hundreds of “air balancing” reports available through the district’s Reopening Readiness Dashboard. Officials have now released reports for nearly all of the city’s 215 buildings, including 147 elementary schools to which students and staff are scheduled to return. Many schools have more than one report because the district commissioned a number of retests for schools that had poor ventilation numbers before any action was taken. 

In some schools, the district said it retooled neglected mechanical HVAC systems. There are three kinds of these: “housefan” systems in some of the oldest buildings, classroom unit ventilators, and central air handling systems. For up to 40 others officials decided to install window fans to recirculate air. 

Use of the window fans has been savaged on social media by parents and teachers who said the fans couldn’t protect students against the virus or keep kids comfortable in winter. Experts, however, told Chalkbeat the fans were a good strategy to improve ventilation.

National data indicates that schools aren’t major vectors for virus transmission in earlier grades. But it can be tough to curb transmission in regions with high rates of the coronavirus.

Philadelphia’s positivity rate was 6.3% as of Jan. 24, about one percentage point lower than when the district tried to reopen in November. The Pennsylvania Department of Education guidelines and the MOA with the teachers union say a hybrid model is acceptable if the city positivity rate is below 10%.

But with new variants of the coronavirus circulating, many are urging caution.

The district is also dealing with a legacy of distrust and past problems, such as temporarily closing schools to deal with loose asbestos and the botched construction project at Benjamin Franklin High School for the co-location with Science Leadership Academy. 

“The Hite administration has a track record of not putting health and safety of students and staff first,” said Charlie McGeehan, a member of Caucus of Working Educators and teacher at the U School. He said the fans being used in some schools “are the same as in my dorm room in college … this does not bring me to trusting the district.”

District officials, the Philadelphia Health Department and public health experts at Children’s Hospital of Philadelphia and the Centers for Disease Control and Prevention all support returning to in-person school for younger students.

Both Hite and district chief operating officer Reggie McNeil have described ventilation as an additional layer of protection to supplement wearing a mask, social distancing, and vigilant hygiene practices. But ventilation looms large in the public’s mind as crucial to safety.

Breaking down the analysis

Chalkbeat took a close look at the district’s ventilation reports to try to determine whether enough rooms were adequately ventilated compared to the number of students who chose hybrid learning. We found that all but 9 schools — 94% — meet the minimum accepted standard. 

We determined how many schools had enough adequately ventilated rooms for at least 10 occupants, and compared that number to the number of students who planned to return. We took into account that due to the cohorting system, only half the returning students would be in the building at the same time. 

The district’s ventilation reports use the 15 CFM per person standard to measure the safe occupancy of each room. Contractors also measured safe occupancy by social distancing standards, and the lower of the two numbers will be enforced.

Industrial hygienist David Krause said the ventilation standard is not remotely close to the air flow needed to curb the spread of a contagious virus. 

“The current code was never meant to control infections in non-healthcare settings. It was intended to … control body odor, nothing more,” Krause said.

Typically, ventilation for disease control is measured by air changes per hour, the rate at which outdoor air replaces indoor air, Krause said. The minimum ventilation that hospitals must have is 6 air changes per hour, and according to a Harvard study, schools should aim for 5 air changes per hour. 

Chalkbeat’s analysis indicates that the average city classroom with one of the district-installed fans has a rate of 2 to 2.5 air changes per hour. To reduce the probability of infection by about 90%, 6 air changes per hour are required; 2 air changes per hour reduces risk by less than 70%.

Still, the district’s ventilation numbers look better than they did several months ago. A Chalkbeat analysis from October found that only one-third of classrooms could safely hold 15 or more people. Since then, the district has ordered more than 1,000 fans to help remediate ventilation in its classrooms.

The fans, manufactured by Comfort Zone and Lasko, recirculate contaminated indoor air with outdoor air, and provide about 250 to 300 CFM of ventilation to any given room. Officials are aiming to have all the fans installed by Feb. 8, when staff return to schools, and McNeil said the work is now 37% complete. 

Hite mistakenly said during last Thursday’s school board meeting that each fan would be equipped with a gauge to measure temperature and CFM in real time, but later corrected himself.

While the fans are a good step, Krause said that ventilation measures should be supplemented with air filtration. 

Ventilation takes indoor air and replaces it with outdoor air, while the filters clean indoor air and spit it back out into the room. Both approaches add an extra layer of safety, but with filtration, students wouldn’t have to worry as much about cold air blowing into their classroom. It’s a more expensive approach than simply improving ventilation with window fans, but one that Krause says is affordable.

In New York City and Chicago, the school districts rushed to purchase air purifiers at the beginning of the school year, but Philadelphia didn’t. McNeil said that’s because most high-quality filters would damage mechanical ventilation systems in many of Philadelphia’s older school buildings. In place of installing filters, the district is looking at potentially adding portable air purifiers to some rooms with fans. 

Krause said he commends the district for testing and remediating antiquated ventilation systems, but questions the adequacy of the efforts to protect students and teachers. 

“What you’re doing is you’re peeling back the bandage on a wound in the United States that schools, the place we send our children, have not been a safe environment with respect to ventilation,” Krause said.

Dale Mezzacappa contributed to this report. 
Gabrielle LaMarr LeMee contributed data analysis.

Ventilation data note

How we calculated the maximum occupancy

The safe occupancy measures in this table are based on the School District of Philadelphia’s ventilation reports, which use a 15 CFM per person standard. That’s not the standard experts say is needed to significantly reduce the spread of COVID-19.

We calculated maximum occupancy numbers by adding up the safe occupancy of each school’s classrooms and then subtracting any rooms that were deemed safe for fewer than 10 people.

We then compared each school’s maximum occupancy to the number of students returning to that school for hybrid learning. Under a hybrid model, only half of the students who opted to return would be in school on a given day. So, if the school’s maximum occupancy exceeded half the number of students who chose hybrid learning, we deemed the school “safe.”

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Most Philadelphia school ventilation meets the district’s standard for safe occupancy for returning K-2 students
School Name All K-2 students Students returning Percent students returning Max Occupancy Safe by district standards for returning students
Mayfair School 659 176 27% 1111 Yes
Anne Frank School 652 266 41% 160 Yes
Solomon Solis-Cohen School 560 185 33% 189 Yes
Clara Barton School 527 147 28% 679 Yes
J. Hampton Moore School 511 167 33% 464 Yes
Edwin Forrest School 452 141 31% 299 Yes
William H. Loesche School 445 190 43% 618 Yes
Lewis Elkin School 384 21 5% 873 Yes
James R. Lowell School 363 100 28% 501 Yes
Gilbert Spruance School 360 62 17% 365 Yes
Louis H. Farrell School 355 122 34% 186 Yes
Laura H. Carnell School 347 55 16% 881 Yes
Frances E. Willard School 346 96 28% 14 No
Juniata Park Academy 306 74 24% 860 Yes
Southwark School 305 99 32% 275 Yes
Stephen Decatur School 295 178 60% 683 Yes
Henry W. Lawton School 282 94 33% 731 Yes
Rhawnhurst School 280 72 26% 428 Yes
John H. Webster School 263 97 37% 387 Yes
Alexander K. McClure School 262 62 24% 358 Yes
Thomas Holme School 261 103 39% 1268 Yes
Philip H. Sheridan School 258 78 30% 349 Yes
Ethan Allen School 256 33 13% 423 Yes
Joseph Greenberg School 252 124 49% 553 Yes
A.L. Fitzpatrick School 247 126 51% 804 Yes
Robert B. Pollock School 247 65 26% 38 Yes
Albert M. Greenfield School 239 71 30% 462 Yes
Olney School 233 33 14% 327 Yes
General George A. McCall School 232 70 30% 525 Yes
Fox Chase School 232 125 54% 339 Yes
Sadie Alexander School 229 155 68% 485 Yes
Joseph H. Brown School 228 55 24% 0 No
James J. Sullivan School 222 29 13% 598 Yes
Hamilton Disston School 222 65 29% 604 Yes
John Hancock Demonstration School 220 129 59% 295 Yes
John M. Patterson School 219 70 32% 1041 Yes
Stephen Girard School 219 66 30% 0 No
Francis Hopkinson School 218 45 21% 625 Yes
Bayard Taylor School 217 70 32% 73 Yes
Watson Comly School 215 131 61% 406 Yes
Thomas G. Morton School 212 45 21% 464 Yes
Bridesburg School 212 116 55% 522 Yes
William Cramp School 208 30 14% 575 Yes
Andrew Jackson School 206 42 20% 538 Yes
Horatio B. Hackett School 204 98 48% 411 Yes
John B. Kelly School 202 35 17% 575 Yes
Benjamin Franklin School 202 50 25% 52 Yes
Joseph W. Catharine School 200 37 19% 152 Yes
Andrew J. Morrison School 200 103 52% 509 Yes
William M. Meredith School 199 116 58% 582 Yes
Alexander Adaire School 199 50 25% 126 Yes
John Barry School 192 59 31% 427 Yes
Richmond School 191 85 45% 479 Yes
Honorable Luis Munoz-Marin School 190 77 41% 310 Yes
Prince Hall School 189 57 30% 849 Yes
George W. Nebinger School 184 47 26% 413 Yes
Julia de Burgos School 184 95 52% 484 Yes
Bache-Martin School 176 127 72% 257 Yes
Thurgood Marshall School 176 37 21% 85 Yes
Thomas K. Finletter School 175 24 14% 931 Yes
Francis S. Key School 172 91 53% 547 Yes
Mary M. Bethune School 172 56 33% 37 Yes
Cayuga School 171 59 35% 443 Yes
Charles W. Henry School 171 98 57% 588 Yes
Eliza B. Kirkbride School 170 83 49% 659 Yes
William Rowen School 167 30 18% 150 Yes
Henry C. Lea School 165 37 22% 232 Yes
Ellwood School 162 45 28% 0 No
John H. Taggart School 159 59 37% 484 Yes
Joseph Pennell School 159 22 14% 912 Yes
Franklin S. Edmonds School 158 21 13% 679 Yes
Allen M. Stearne School 157 55 35% 289 Yes
Tanner G. Duckrey School 155 33 21% 622 Yes
Kennedy C. Crossan School 154 71 46% 161 Yes
Shawmont School 152 91 60% 0 No
Cook-Wissahickon School 150 72 48% 197 Yes
James Rhoads School 148 91 61% 250 Yes
Add B. Anderson School 147 18 12% 80 Yes
Eleanor C. Emlen School 147 30 20% 348 Yes
Jenks Academy for Arts and Sciences 147 52 35% 349 Yes
Richard R. Wright School 144 36 25% 347 Yes
Abram S. Jenks School 140 49 35% 209 Yes
Potter-Thomas School 139 36 26% 469 Yes
S. Weir Mitchell School 138 63 46% 610 Yes
Samuel Powel School 138 1 1% 0 No
Dr. Ethel Allen School 138 23 17% 249 Yes
William C. Bryant School 136 17 13% 594 Yes
John Moffet School 136 54 40% 332 Yes
D. Newlin Fell School 135 49 36% 419 Yes
William H. Ziegler School 134 40 30% 358 Yes
Alain Locke School 132 25 19% 682 Yes
Thomas Mifflin School 132 45 34% 381 Yes
John Marshall School 132 28 21% 287 Yes
Benjamin B. Comegys School 129 12 9% 219 Yes
George W. Childs School 129 43 33% 882 Yes
Kenderton Elementary School 128 41 32% 479 Yes
Thomas M. Peirce School 126 28 22% No report
Anna B. Day School 123 19 15% 326 Yes
Edward Heston School 122 21 17% 431 Yes
Edward T. Steel School 120 36 30% 0 No
Edwin M. Stanton School 119 50 42% 381 Yes
Chester A. Arthur School 119 80 67% 331 Yes
Jay Cooke School 119 50 42% 154 Yes
Penrose School 118 40 34% 1433 Yes
Julia W. Howe School 118 41 35% 272 Yes
William H. Hunter School 117 39 33% 199 Yes
Avery D. Harrington School 116 25 22% 70 Yes
William Dick School 115 63 55% 411 Yes
E. Washington Rhodes School 115 28 24% 845 Yes
John F. Hartranft School 114 32 28% 696 Yes
James Logan School 114 10 9% 1176 Yes
Theodore Roosevelt School 114 34 30% 997 Yes
Samuel Pennypacker School 112 34 30% No report
James G. Blaine School 111 17 15% 855 Yes
Henry H. Houston School 108 47 44% 623 Yes
Lewis C. Cassidy Academics Plus School 107 35 33% 469 Yes
Anna L. Lingelbach School 107 18 17% 245 Yes
Robert E. Lamberton School 106 22 21% 776 Yes
Vare-Washington School 105 56 53% 398 Yes
Isaac A. Sheppard School 105 22 21% 262 Yes
William C. Longstreth School 103 33 32% 201 Yes
General George G. Meade School 103 15 15% 645 Yes
George W. Sharswood School 101 46 46% 154 Yes
William D. Kelley School 100 12 12% 477 Yes
Andrew Hamilton School 98 17 17% 181 Yes
Rudolph Blankenburg School 98 32 33% 431 Yes
William McKinley School 97 10 10% 210 Yes
John Welsh School 95 33 35% 483 Yes
Delaplaine McDaniel School 91 13 14% 584 Yes
General Philip Kearny School 88 15 17% 15 Yes
Overbrook Educational Center 86 52 60% 432 Yes
Henry A. Brown School 85 24 28% 623 Yes
Samuel Gompers School 80 30 38% 217 Yes
Paul L. Dunbar School 80 16 20% 327 Yes
Spring Garden School 79 10 13% 316 Yes
John F. McCloskey School 78 12 15% 331 Yes
Morton McMichael School 77 37 48% 770 Yes
Laura W. Waring School 77 29 38% 0 No
Fitler Academics Plus School 77 12 16% 0 No
F. Amedee Bregy School 71 24 34% 400 Yes
James Dobson School 67 35 52% 306 Yes
Overbrook Elementary School 63 4 6% 306 Yes
Robert Morris School 62 6 10% 224 Yes
Martha Washington School 59 29 49% 367 Yes
Edward Gideon School 59 12 20% 646 Yes
James R. Ludlow School 59 30 51% 497 Yes
Widener Memorial School 26 21 81% 960 Yes

An earlier version of this story listed incorrect data for Watson Comly School and Overbrook Elementary School. Those schools have been updated.

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