Exposure of Children to Ultrafine Particles in Primary Schools in Portugal

Utility of outdoor central site monitoring in assessing exposure of school children to ultrafine particles

Epidemiological studies investigating the association between daily particle exposure and health effects are frequently based on a single monitoring site located in an urban background. Using a central site in epidemiological time-series studies has been established based on the premises of low spatial variability of particles within the areas of interest and hence the adequacy of the central sites to monitor the exposure. This is true to a large extent in relation to larger particles (PM_2.5, PM₁₀) that are typically monitored and regulated. However, the distribution of ultrafine particles (UFP), which in cities predominantly originate from traffic, is heterogeneous. With increasing pressure to improve the epidemiology of UFP, an important question to ask is, whether central site monitoring is representative of community exposure to this size fraction of particulate matter; addressing this question is the aim of this paper. To achieve this aim, we measured personal exposure to UFP, expressed as particle number concentration (PNC), using Philips Aerasense Nanotracers (NT) carried by the participants of the study, and condensation particle counters (CPC) or scanning mobility particle sizers (SMPS) at central fixed-site monitoring stations. The measurements were conducted at three locations in Brisbane (Australia), Cassino (Italy) and Accra (Ghana). We then used paired t-tests to compare the average personal and average fixed-site PNC measured over the same 24-h, and hourly, periods. We found that, at all three locations, the 24-h average fixed-site PNC was no different to the personal PNC, when averaged over the study period and all the participants. However, the corresponding hourly averages were significantly different at certain times of the day. These were generally times spent commuting and during cooking and eating at home. Our analysis of the data obtained in Brisbane, showed that maximum personal exposure occurred in the home microenvironment during morning breakfast and evening dinner time. The main source of PNC for personal exposure was from the home-microenvironment. We conclude that the 24-h average PNC from the central-site can be used to estimate the 24-h average personal exposure for a community. However, the hourly average PNC from the central site cannot consistently be used to estimate hourly average personal exposure, mainly because they are affected by very different sources.

Indoor Air Pollution and the Health of Vulnerable Groups: A Systematic Review Focused on Particulate Matter (PM), Volatile Organic Compounds (VOCs) and Their Effects on Children and People with Pre-Existing Lung Disease

Air pollution affects health, but much of the focus to this point has been on outdoor air. Higher indoor pollution is anticipated due to increasingly energy-efficient and less leaky buildings together with more indoor activities. Studies of indoor air pollution focusing on children and people with respiratory disease from the database Web of Science (1991–2021) were systemically reviewed according to the PRISMA guidelines, with 69 studies included in the final selection. Emissions from building materials affected indoor air quality, and ventilation also had an influence. The main indoor air pollutants are Volatile Organic Compounds (VOCs) and Particulate Matter (PM). PM sources included smoking, cooking, heating, candles, and insecticides, whereas sources of coarse particles were pets, housework and human movements. VOC sources included household products, cleaning agents, glue, personal care products, building materials and vehicle emissions. Formaldehyde levels were particularly high in new houses. Personal exposure related to both indoor and outdoor pollutant levels, highlighting home characteristics and air exchange rates as important factors. Temperature, humidity, educational level, air purifiers and time near sources were also related to personal exposure. There was an association between PM and Fractional exhaled Nitric Oxide (FeNO), lung function, oxygen saturation, childhood asthma and symptoms of chronic obstructive pulmonary disease (COPD) patients. High VOCs were associated with upper airways and asthma symptoms and cancer. Effective interventional studies for PM in the future might focus on human behavior together with air purifiers and increased ventilation, whereas VOC interventions might center more on building materials and household products, alongside purification and ventilation.

Exhaled breath condensate pH determinants in school-aged children: A population-based study

BACKGROUND

Exhaled breath condensate (EBC) pH is a promising biomarker of airway inflammation. Lack of method standardization and interstudy variability precludes its use in clinical practice. While endogenous determinants have been described, underlying mechanisms for variability are mostly unknown. Thus, we aimed to assess the association between asthma and EBC pH in children, while studying potential environmental factors for interstudy variability.

METHODS

A cross-sectional analysis of exhaled breath condensates from 613 children, aged 7-12 years, was conducted. Assessments included lung function and airway reversibility, exhaled nitric oxide, allergic sensitization, and body mass index (BMI). Indoor air quality (IAQ) was assessed in children's classrooms during 5 school days. Post-deaeration EBC pH showed a bimodal distribution, and the sample was split into acidic and alkaline groups. Regression models were constructed to assess the effects of asthma and asthma adjusted to IAQ parameters on EBC pH.

RESULTS

Following adjustment to gender and BMI, asthma was significantly associated with a lower EBC pH in the acidic group. The effect of asthma on EBC pH was independent of IAQ, in both groups. In the acidic group, EBC pH was significantly affected by temperature [β = -0.09 (-0.15, -0.02)] and PM 2.5 concentration [β = -0.16 (-0.32, -0.01)], and in the alkaline group by relative humidity [β = 0.07 (0.02, 0.13)] and concentration of endotoxins [β = -0.06 (-0.1, -0.01)].

CONCLUSION

Our study shows that in addition to individual determinants such as asthma, environmental factors may influence and should be taken into consideration when interpreting EBC pH level in children.

Exposure to ultrafine particles in children until 18 years of age: A systematic review

Airborne ultrafine particles (UFP) have been related to adverse health effects, but exposure in vulnerable population groups such as children is still not well understood. We aim to review the scientific literature regarding personal exposure to UFP in different microenvironments in populations until 18 years of age. The bibliographical search was carried out in July 2019 using the online database PubMed and was completed with references in articles found in the search. We selected the studies that used continuous counters and measured UFP levels in both specific microenvironment (houses, schools, transport, etc) and personal exposure. Finally, 32 studies fulfilled the criteria: of these, 10 analyzed personal exposure and 22 examined UFP levels in the microenvironment (especially in schools or nurseries (18/22)) and five in various microenvironments (including dwellings and means of transport, where exposure levels were higher). The characteristics of the microenvironments with the greatest levels of UFP were being close to heavy traffic or near cooking and cleaning activities. This review revealed the wide differences in exposure assessment methodologies that could lead to a lack of uniform and comparable information about the real UFP exposure in children.

(Ultra) Fine particle concentrations and exposure in different indoor and outdoor microenvironments during physical exercising

Although regular exercise improves overall well-being, increased physical activity results in enhanced breathing which consequently leads to elevated exposure to a variety of air pollutants producing adverse effects. It is well-known that one of these ambient air contaminants is ultrafine particles (UFP). Thus, this study aimed to (1) examine exposure to particle number concentrations (PNC) in size ranging from N20-1000 nm in different sport environments and (2) estimate the respective inhalation doses across varying activity scenarios based upon the World Health Organization recommendations for physical activity. PNC were continuously monitored (TSI P-Trak™ condensation particle counter) outdoors (Out1-Out2) and indoors (Ind1-Ind2; fitness clubs) over 4 weeks. Outdoor PNC (total median 12 563 # cm^-3; means of 20 367 # cm^-3 at Out1 and 7 122 # cm^-3 at Out2) were approximately 1.6-fold higher than indoors (total median 7 653 # cm^-3; means of 11 861 # cm^-3 at Ind1 and 14 200 # cm^-3 at Ind2). The lowest doses were inhaled during holistic group classes (7.91 × 10⁷-1.87 × 10⁸ # per kg body weight) whereas exercising with mixed cardio and strength training led to approximately 1.8-fold higher levels. In order to optimize the health benefit of exercises, environmental characteristics of the locations at which physical activities are conducted need to be considered.

Polycyclic aromatic hydrocarbons (PAH) in Portuguese educational settings: a comparison between preschools and elementary schools

The aim of this study was to determine levels and risks due to inhalation exposure to polycyclic aromatic hydrocarbons (PAH) in different educational settings, namely for 3- to 5- year-old and 6- to 10-year-old children. Eighteen PAH (16 priority designated by US Environmental Protection Agency (USEPA) and dibenzo[a,l]pyrene and benzo[j]fluoranthene) were simultaneously collected in indoor and outdoor air at two Portuguese preschools (PS1-PS2) and five elementary schools (ES1-ES5) from March to May 2014. Indoor concentrations at PS and ES were significantly different, with total levels (∑PAHs) 0.721-15.9 ng/m³ at PS1-PS2 and 5.03-23.6 ng/m³ at ES1-ES5. The corresponding outdoor concentrations were, respectively, 1.22-32.7 ng/m³ and 2.6-31.5 ng/m³. Polycyclic aromatic hydrocarbons with 2-3 aromatic rings were predominantly emitted by indoor sources, while compounds with 4-6 aromatic rings were mainly generated by infiltration of ambient PAH pollution to indoors. Excess lifetime risks of lung cancer exceeded the World Health Organization (WHO) designated guideline of 10^-5 in both types of schools (15-42-fold at PS; 15-52-fold at ES). However, total (sum of indoor and outdoor exposure) incremental lifetime cancer risks (ILCR) were below the USEPA level of 10^-6 at all studied institutions and thus considered negligible. Finally, ILCR due to indoor exposure represented 60-75% and 70-85% of the total ILCR at PS and ES, respectively, thus indicating the need for development and implementation of indoor air quality guidelines in educations settings.

Indoor air quality in preschools (3- to 5-year-old children) in the Northeast of Portugal during spring-summer season: pollutants and comfort parameters

Indoor air quality at schools (elementary, primary) has been the subject of many studies; however, there are still relative few data regarding preschool (3- to 5-year-old children) environments. This investigation determined the concentrations of particulate matter (PM)_2.5, total volatile organic compounds (TVOC), formaldehyde, carbon monoxide (CO), and ozone (O₃) as well as the levels of carbon dioxide (CO₂), temperature, and relative humidity (RH) in the indoor and outdoor air of two preschools situated in different geographical regions of Portugal. The indoor concentrations of TVOC, CO, O₃, and CO₂ were predominantly higher at the end of school day compared to early morning periods. The TVOC and CO₂ concentrations were higher indoors than outdoors suggesting predominantly an indoor origin. Outdoor air infiltrations were the major contributing source of CO and O₃ to indoor air in both preschools. The concentrations of all pollutants were within the limits defined by national regulations and international organizations, except for TVOC that exceeded 8-12-fold higher than the recommendation of 0.2 mg/m³ proposed by European Commission. The levels of CO₂ were below the protective guideline of 2250 mg/m³ (Portuguese legislation); however, the observed ranges exceeded the Portuguese margin of tolerance (2925 mg/m³) at the end of school days, indicating the impact of occupancy rates particularly at one of the preschools. Regarding comfort parameters, temperature exerted a significant influence on O₃ concentrations, while RH values were significantly correlated with TVOC levels in indoor air of preschools, particularly during the late afternoon periods.

Indoor pollutant exposure among children with and without asthma in Porto, Portugal, during the cold season

Considering the time spent in enclosed spaces, indoor air pollutants are of major interest because of its possible impact on health. However, to date, few studies have analysed the air concentrations of a large set of indoor pollutants of respiratory health relevance in dwellings, particularly in Portugal. This study aimed to measure the concentrations of air pollutants that are present in residential buildings and to investigate whether some clustering pattern of indoor air pollutants exists in the dwellings of children with (case group) and without asthma (control group). Measurements were taken in 30 and 38 dwellings of asthmatic and non-asthmatic schoolchildren, respectively, located in the city of Porto, Portugal, during the cold season (October 2012-April 2013), to assess the concentrations of 12 volatile organic compounds (VOC), aldehydes, PM_2.5, PM₁₀, bacteria and fungi. Toluene, d-limonene, formaldehyde, PM_2.5, bacteria and fungi are widely present in dwellings, sometimes in relatively high concentrations in reference to WHO guideline values. Moreover, concentrations of CO₂ exceeding 1000 ppm were often encountered, indicating that 70 % of all dwellings had poor ventilation (<4 L/s person). While exposures to common dwelling indoor pollutants are similar for schoolchildren with and without asthma, except for d-limonene levels, the identification and control of VOC and PM sources is important and prudent, especially for vulnerable individuals.

Children exposure to indoor ultrafine particles in urban and rural school environments

Extended exposure to ultrafine particles (UFPs) may lead to consequences in children due to their increased susceptibility when compared to older individuals. Since children spend in average 8 h/day in primary schools, assessing the number concentrations of UFPs in these institutions is important in order to evaluate the health risk for children in primary schools caused by indoor air pollution. Thus, the purpose of this study was to assess and determine the sources of indoor UFP number concentrations in urban and rural Portuguese primary schools. Indoor and outdoor ultrafine particle (UFP) number concentrations were measured in six urban schools (US) and two rural schools (RS) located in the north of Portugal, during the heating season. The mean number concentrations of indoor UFPs were significantly higher in urban schools than in rural ones (10.4 × 10(3) and 5.7 × 10(3) pt/cm(3), respectively). Higher UFP levels were associated with higher squared meters per student, floor levels closer to the ground, chalk boards, furniture or floor covering materials made of wood and windows with double-glazing. Indoor number concentrations of ultrafine-particles were inversely correlated with indoor CO2 levels. In the present work, indoor and outdoor concentrations of UFPs in public primary schools located in urban and rural areas were assessed, and the main sources were identified for each environment. The results not only showed that UFP pollution is present in augmented concentrations in US when compared to RS but also revealed some classroom/school characteristics that influence the concentrations of UFPs in primary schools.