Can changing the timing of outdoor air intake reduce indoor concentrations of traffic‐related pollutants in schools?

Abstract

Traffic emissions have been associated with a wide range of adverse health effects. Many schools are situated close to major roads, and as children spend much of their day in school, methods to reduce traffic-related air pollutant concentrations in the school environment are warranted. One promising method to reduce pollutant concentrations in schools is to alter the timing of the ventilation so that high ventilation time periods do not correspond to rush hour traffic. Health Canada, in collaboration with the Ottawa-Carleton District School Board, tested the effect of this action by collecting traffic-related air pollution data from four schools in Ottawa, Canada, during October and November 2013. A baseline and intervention period was assessed in each school. There were statistically significant (P < 0.05) reductions in concentrations of most of the pollutants measured at the two late-start (9 AM start) schools, after adjusting for outdoor concentrations and the absolute indoor-outdoor temperature difference. The intervention at the early-start (8 AM start) schools did not have significant reductions in pollutant concentrations. Based on these findings, changing the timing of the ventilation may be a cost-effective mechanism of reducing traffic-related pollutants in late-start schools located near major roads. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Practical ImplicationsThis study found that adjusting the ventilation system to operate earlier in the morning, prior to high traffic commute periods, significantly reduced traffic-related air pollutants within late-start schools (9 AM) located near major roads. Given the ease of implementation and cost-effectiveness, this intervention may be a feasible approach for improving indoor air quality in schools and other public buildings with heating, ventilation, and air conditioning (HVAC) systems.

Personal measurement of exposure to black carbon and ultrafine particles in schoolchildren from PARIS cohort (Paris, France)

“…The infiltration of particles (mostly BC) from outside to inside the classroom thus seems to be higher in the morning than in the afternoon, perhaps due to window openings before the start of classes coinciding with the high traffic in the morning rush hour. MacNeill et al showed that a simple intervention such as adjusting the ventilation system to operate earlier in the morning, prior to high traffic commute periods, significantly reduced traffic‐related air pollutants (including UFP and fine particles) in schools located near major roads with heating, ventilating and air‐conditioning systems.…”

Improving indoor air quality, health and performance within environments where people live, travel, learn and work

“…In schools, numerous investigations have reported the positive effects of increased ventilation and as such, improved IAQ on respiratory symptoms, absenteeism, test performance and long-term academic performance in school children. The proven effectiveness of air filtration systems that are built into school HVAC systems 231,232 as well as stand-alone air filtration systems in classrooms relying on natural ventilation 233 in reducing indoor pollutants of outdoor origin suggests they represent a critical mitigation measure at schools located near heavily trafficked roads, industry and other important sources of air toxics. Future research should focus on identifying the optimal technologies for removing specific indoor air pollutants (e.g.…”

Evaluation of daily time spent in transportation and traffic-influenced microenvironments by urban Canadians

“…In the present study, household income did not have a significant association with attending a school or daycare within one block of a roadway with moderate to heavy traffic, and little variation was observed between cities. Concerns over potential health effects in children and youth have led to recent investigations of possible interventions to reduce exposure to TRAP in schools (MacNeill et al 2016 , van der Zee et al 2017 ).…”