On-site passive flux sampler measurement of emission rates of carbonyls and VOCs from multiple indoor sources

In indoor environments with high levels of air pollution, it is desirable to remove major sources of emissions to improve air quality. In order to identify the emission sources that contribute most to the concentrations of indoor air pollutants, we used passive flux samplers (PFSs) to measure emission rates of carbonyl compounds and volatile organic compounds (VOCs) from many of the building materials and furnishings present in a room in a reinforced concrete building in Tokyo, Japan. The emission flux of formaldehyde from a desk was high (125 μg/m²/h), whereas fluxes from a door and flooring were low (21.5 and 16.5 μg/m²/h, respectively). The emission fluxes of toluene from the ceiling and the carpet were high (80.0 and 72.3 μg/m²/h, respectively), whereas that from the flooring was low (9.09 μg/m²/h). The indoor and outdoor concentrations of formaldehyde were 61.5 and 8.64 μg/m³, respectively, and those of toluene were 43.2 and 17.5 μg/m³, respectively. The air exchange rate of the room as measured by the perfluorocarbon tracer (PFT) method was 1.84/h. Taking into consideration the area of the emission sources, the carpet, ceiling, and walls were identified as the principal emission sources, contributing 24%, 20%, and 22% of the formaldehyde, respectively, and 22%, 27%, and 14% of the toluene, respectively, assuming that the emission rate from every major emission sources could be measured. In contrast, the door, the flooring, and the desk contributed little to the indoor levels of formaldehyde (1.0%, 0.54%, and 4.1%, respectively) and toluene (2.2%, 0.31%, and 0.85%, respectively).     

Feasibility study of desiccant air-conditioning system in Thailand

The objective of this study was to conduct an experimental analysis to investigate the performance and energy saving of the well-known desiccant air-conditioning system in Thailand. The system was composed of a silica gel bed, a split type air-conditioner (1.5 ton refrigeration) installed in a room of volume 76.8 m³, air ducts and a blower. Its design allows us to adjust the percentages of return air, outdoor air and indoor air mixed to the air leaving the desiccant, and desiccant bed thickness as well. Tests were conducted on several days with relatively similar ambient conditions. Under the test conditions used here, a 5 cm bed thickness is recommended with a maximum adsorption rate of 473 g/h. The optimum percentages of air ratios are as follows: 15% outdoor air, 15% return air (mixed together at the desiccant bed inlet) and 70% of indoor air mixed to the dry air leaving the desiccant. The corresponding electricity saving was about 24%. As expected, simple economic analysis indicated that the desiccant air-conditioning is only viable for large cooling capacities and central air-conditioned buildings. The payback period is about 4 yr.     

Variation in indoor particle number and PM2.5 concentrations in a radio station surrounded by busy roads before and after an upgrade of the HVAC system

Indoor particle number and PM_2.5 concentrations were investigated in a radio station surrounded by busy roads. Two extensive field measurement campaigns were conducted to determine the critical parameters affecting indoor air quality. The results indicated that indoor particle number and PM_2.5 concentrations were governed by outdoor air, and were significantly affected by the location of air intake and design of HVAC system. Prior to the upgrade of the HVAC system and relocation of the air intake, the indoor median particle number concentration was 7.4×10³ particles/cm³ and the median PM_2.5 concentration was 7 μg/m³. After the relocation of air intake and the redesign of the HVAC system, the indoor particle number concentration was between 2.3×10³ and 3.4×10³ particles/cm³, with a median value of 2.7×10³ particles/cm³, and the indoor PM_2.5 concentration was in the range of 3–5 μg/m³, with a median value of 4 μg/m³. By relocating the air intake of the HVAC, the outdoor particle number and PM_2.5 concentrations near the air intake were reduced by 35% and 55%, respectively. In addition, with the relocation of air intake and the redesign of the HVAC system, the particle number penetration rate was reduced from 42% to 14%, and the overall filtration efficiency of the HVAC system (relocation of air intake, pre-filter, AHU and particle losses in the air duct) increased from 58% to 86%. For PM_2.5, the penetration rate after the upgrade was approximately 18% and the overall filtration efficiency was 82%. This study demonstrates that by using a comprehensive approach, including the assessment of outdoor conditions and characterisation of ventilation and filtration parameters, satisfactory indoor air quality can be achieved, even for those indoor environments facing challenging outdoor air conditions.     

一次回风送风再热与新风预冷互补的节能研究

对于一次回风空调系统,夏季工况,当空调区湿负荷较大时,采用露点送风只能保证设定温度,而湿度将会偏大,影响人体热舒适;若增加再热,又会出现冷热抵消现象。提出了利用室外新风热量再热来改善室内热舒适状况的方案。通过工程案例计算分析,结果表明:利用新风再热可减少再热送风系统6%~15%的能耗,认为送风再热与新风预冷互补措施能在一定程度上降低空调能耗,提高室内热舒适。     

An in‐situ thermally regenerated air purifier for indoor formaldehyde removal

Formaldehyde is a common indoor pollutant that is an irritant and has been classified as carcinogen to humans. Adsorption technology is safe and stable and removes formaldehyde efficiently, but its short life span and low adsorption capacity limit its indoor application. To overcome these limitations, we propose an in‐situ thermally regenerated air purifier (TRAP) which self‐regenerates as needed. This purifier has four working modes: cleaning mode, regeneration mode, exhaust mode, and outdoor air in‐take mode, all of which are operated by valve switching. We developed a real‐scale TRAP prototype with activated carbon as adsorbent. The experimental testing showed that the regeneration ratios for formaldehyde of TRAP were greater than 90% during 5 cycles of adsorption‐regeneration and that through the 5 cycles, there was no damage to the adsorption material as confirmed by scanning electron microscope (SEM) and Brunauer‐Emmett‐Teller (BET) tests. The total energy consumption by the prototype for purifying 1000 m³ indoor air was 0.26 kWh. This in‐situ thermal‐regeneration method can recover the purifier's adsorption ability through at least five cycles.     

Screening of formaldehyde indoor sources and quantification of their emission using a passive sampler

The formaldehyde emission rates from building and furniture materials in 24 student rooms were measured using a passive sampling method parallel to a monitoring of indoor and outdoor concentrations. This passive tool represents an interesting alternative to standard dynamic methods as it is easier to implement for field investigation. Although the indoor formaldehyde concentrations (21.3 μg m⁻³ on average) are at a medium level, consistent with earlier published results, the recorded emission rates are globally low (from 1 to 15 μg m⁻² h⁻¹) except for the high emission of beds identified in one building (87.3 μg m⁻² h⁻¹ on average). Data analysis revealed that the emissions released from furniture and building materials are the main contributions to the indoor formaldehyde concentrations with 45 and 43% on average. The high formaldehyde levels in rooms are mainly explained by the rise of formaldehyde emissions from indoor materials with temperature although the buildings and the furniture were older than 7 years. Basing on the data of emission rates, outdoor concentrations and air exchange rates, a one compartment mass balance model was used to calculate indoor concentrations. A good agreement was found between the predictions of the model and the measured indoor concentrations. This methodology could lead to the definition of arrangements for the efficient reduction of indoor formaldehyde levels.     

Effect of mechanically induced ventilation on the indoor air quality of building envelopes

Experiments were conducted to study the effect of mechanically induced fresh-air ventilation on the indoor air quality (IAQ) of the Tuskegee Healthy House (THH), selecting the outdoor weather conditions almost identical during the “fan OFF” and “fan ON” periods. Measurements of outdoor and indoor temperature and relative humidity (RH), in addition to the indoor dust particle concentration levels and interior wall moisture content, were systematically carried out during the summer month of August 2008. Results show that the effect of mechanically induced ventilation (“fan ON” period) is to raise the indoor RH, interior wall moisture content, and indoor dust particle concentration values significantly above those measured during the “fan OFF” period. The indoor temperature increases only slightly during the “fan ON” period.     

Organic air pollutants inside and outside residences in Shimizu, Japan: levels, sources and risks

Concentrations of 38 organic air pollutants including aromatic hydrocarbons (AHCs), carbonyl compounds (CCs), volatile organic halogenated compounds (VOHCs), and organophosphorus compounds (OPCs) were measured in indoor and outdoor air in an industrial city, Shimizu, Shizuoka Prefecture, Japan. Levels of pollutants tended to be higher indoors than outdoors in both summer and winter except for benzene, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and dichlorvos (DDVP). This trend was especially pronounced for CCs such as formaldehyde and acetaldehyde. For the organic air pollutants, the concentrations of AHCs and VOHCs substantially increased in winter, but not those of CCs and OPCs; the trends were similar for both indoors and outdoors. We investigated possible indoor sources of pollutants statistically. Multiple regression analysis of corresponding indoor and outdoor concentrations and the responses to our questionnaire showed that indoor concentrations of certain AHCs were significantly affected by their outdoor concentrations and cigarette smoking. For formaldehyde, indoor concentrations were significantly affected by house age and the presence of carpet or pets. For p-dichlorobenzene (pDCB), the concentrations in bedroom trended to be higher than those in other indoors and outdoors, suggested that mothballs for clothes present in bedrooms are the principal indoor source of pDCB. We compared indoor and outdoor pollutant concentrations to acceptable risk limits for 11 organic air pollutants. In indoors without smoking samples, the geometric mean concentrations of benzene, formaldehyde, acetaldehyde, carbon tetrachloride, pDCB, and DDVP exceeded the equivalent concentration representing the upper bound of one-in-one-hundred-thousand (1x10(-5)) excess risk over a lifetime of exposure.     

Exhaust ventilation in attached garages improves residential indoor air quality

Previous research has shown that indoor benzene levels in homes with attached garages are higher than homes without attached garages. Exhaust ventilation in attached garages is one possible intervention to reduce these concentrations. To evaluate the effectiveness of this intervention, a randomized crossover study was conducted in 33 Ottawa homes in winter 2014. VOCs including benzene, toluene, ethylbenzene, and xylenes, nitrogen dioxide, carbon monoxide, and air exchange rates were measured over four 48‐hour periods when a garage exhaust fan was turned on or off. A blower door test conducted in each garage was used to determine the required exhaust fan flow rate to provide a depressurization of 5 Pa in each garage relative to the home. When corrected for ambient concentrations, the fan decreased geometric mean indoor benzene concentrations from 1.04 to 0.40 μg/m³, or by 62% (P<.05). The garage exhaust fan also significantly reduced outdoor‐corrected geometric mean indoor concentrations of other pollutants, including toluene (53%), ethylbenzene (47%), m,p‐xylene (45%), o‐xylene (43%), and carbon monoxide (23%) (P<.05) while having no impact on the home air exchange rate. This study provides evidence that mechanical exhaust ventilation in attached garages can reduce indoor concentrations of pollutants originating from within attached garages.     

Real-time measurements of PM2.5 and ozone to assess the effectiveness of residential indoor air filtration in Shanghai homes

Portable air cleaners are increasingly used in polluted areas in an attempt to reduce human exposure; however, there has been limited work characterizing their effectiveness at reducing exposure. With this in mind, we recruited forty-three children with asthma from suburban Shanghai and deployed air cleaners (with HEPA and activated carbon filters) in their bedrooms. During both 2-week filtration and non-filtration periods, low-cost PM_2.5 and O₃ air monitors were used to measure pollutants indoors, outdoors, and for personal exposure. Indoor PM_2.5 concentrations were reduced substantially with the use of air cleaners, from 34 ± 17 to 10 ± 8 µg/m³, with roughly 80% of indoor PM_2.5 estimated to come from outdoor sources. Personal exposure to PM_2.5 was reduced from 40 ± 17 to 25 ± 14 µg/m³. The more modest reductions in personal exposure and high contribution of outdoor PM_2.5 to indoor concentrations highlight the need to reduce outdoor PM_2.5 and/or to clean indoor air in multiple locations. Indoor O₃ concentrations were generally low (mean = 8±4 ppb), and no significant difference was seen by filtration status. The concentrations of pollutants and the air cleaner effectiveness were highly variable over time and across homes, highlighting the usefulness of real-time air monitors for understanding individual exposure reduction strategies.     

Penetration of nitrogen oxides and particles from outdoor into indoor air and removal of the pollutants through filtration of incoming air

We studied the effect of ventilation and air filtration systems on indoor air quality in a children's day-care center in Finland. Ambient air nitrogen oxides (NO, NO2) and particles (TSP, PM10) were simultaneously measured outdoors and indoors with automatic nitrogen oxide analyzers and dust monitoring. Without filtration nitrogen oxides and particulate matter generated by nearby motor traffic penetrated readily indoors. With chemical filtration 50-70% of nitrogen oxides could be removed. Mechanical ventilation and filtration also reduced indoor particle levels. During holidays and weekends when there was no opening of doors and windows and no particle-generating activity indoors, the indoor particle level was reduced to less than 10% of the outdoor level. At times when outdoor particle concentrations were high during weekdays, the indoor level was about 25% of the outdoor level. Thus, the possible adverse health effects of nitrogen oxides and particles indoors could be countered by efficient filtration. We also showed that inclusion of heat recovery equipment can make new ventilation installations economical.     

Achieving 'excellent' indoor air quality in commercial offices equipped with air-handling unit--respirable suspended particulate

A study was carried out to investigate the feasibility of achieving ultra low respirable suspended particulates (RSP) in commercial offices without major modification of existing ventilation systems by enhancing the particulates removal efficiency of existing central ventilation systems. Four types of filters which include pre-filters, cartridge filters, bag filters and high efficiency particulates air (HEPA) filters were tested in a commercial building in Causeway Bay. The results show that an RSP objective of <20 microg/m3 could be met by removing RSP from both the return air and outdoor air supply simultaneously. This level of performance is classed as 'excellent' by the Hong Kong Government, Environmental Protection Department. Filters with efficiency that exceed 80% placed both in the return air and outdoor air were sufficient to meet the objective. It is not necessary to install HEPA filters to achieve the 'excellent' class. The outdoor air filter has great influence on the steady state indoor RSP concentration while the effective cleaning rate is governed by the return air filter. Higher efficiency filters increased the static drop but the volume flow of the air fan was not affected significantly. The additional cost incurred was <5% of the existing operation cost. PRACTICAL IMPLICATIONS: This paper reports a field study of RSP control for an indoor office environment. The results are directly applicable to building service engineering in the design of ventilation systems using air-handling units. Field observations indicated that indoor RSP in an office environment could be suppressed below 20 microg/m3 within 1 h by the simultaneous filtration of outdoor air and return air. Outdoor air filtration has a great influence on the steady state indoor concentration and return air filtration governs the cleaning rate. It is believed that the results of this study could be extended to the cleaning of other indoor pollutants such as volatile organic compounds.     

Impact of psycho-social factors on perception of the indoor air environment studies in 12 office buildings

The main function of a mechanically ventilated office building is to provide a healthy and comfortable working environment for occupants, while maintaining minimum energy consumption. Twelve mechanically ventilated buildings were selected. They varied greatly in surface area, number of floors, occupant density, and building use. The indoor air quality, thermal comfort, energy consumption, and perception of occupants were investigated in these buildings. A total of 877 subjects participated in the questionnaire survey during the hot summer months of June, July, and August, and during the cold winter months of January, February, and March. The questions included in the questionnaire dealt with health, environmental sensitivity, work area satisfaction, personal control of the workstations environment, and job satisfaction. Measured parameters concerning the quality of indoor air included ventilation rate, concentration of TVOC, CO₂, CO, RH, and formaldehyde. The thermal comfort parameters included room air, mean radiant, plane radiant asymmetry, and dew point temperatures, as well as air velocity and turbulence intensity. Monthly energy consumption data was also gathered for each building. Ventilation performance, in terms of air flow rate and indoor air quality, was compared with the ASHRAE Standard 62-89R (Ventilation for Acceptable Indoor Air Quality. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [1]). The measured and calculated thermal environmental results were also compared with the ASHRAE Standard 55-92 (Thermal Environmental Conditions for Human Occupancy. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [2]). CO₂ and CO levels satisfied the recommended limits. The outdoor airflow rate was half that recommended in only one building. The formaldehyde and TVOC levels were moderately higher than suggested comfort levels. However, more than 56% of the occupants rated dissatisfaction with the indoor air quality. Only 63% of the indoor climatic observations fell within the ASHRAE Standard 55-92 summer comfort zone; 27% in the winter. However, only 69% of those surveyed agreed with the comfort zones. More symptoms were reported by workers who perceived IAQ to be poor. Positive relationships were observed between the job satisfaction and satisfaction with office air quality, ventilation, work area temperature, and ratings of work area environment. However, job dissatisfaction did not correlate with symptom reports. The occupants were more dissatisfied with IAQ when they preferred more air movement. In other words, the higher the perceived air movement, the greater the satisfaction with IAQ.     

Correlating indoor and outdoor temperature and humidity in a sample of buildings in tropical climates

The incidence of several respiratory viral infections has been shown to be related to climate. Because humans spend most of their time indoors, measures of indoor climate, rather than outdoor climate, may be better predictors of disease incidence and transmission. Therefore, understanding the relationship between indoor and outdoor climate will help illuminate their influence on the seasonality of diseases caused by respiratory viruses. Indoor-outdoor relationships between temperature and humidity have been documented in temperate regions, but little information is available for tropical regions, where seasonal patterns of respiratory viral diseases differ. We have examined indoor-outdoor correlations of temperature, relative humidity (RH), and absolute humidity (AH) over a 1-year period in each of seven tropical cities. Across all cities, the average monthly indoor temperature was 25 ± 3°C (mean ± standard deviation) with a range of 20–30°C. The average monthly indoor RH was 66 ± 9% with a range of 50–78%, and the average monthly indoor AH was 15 ± 3 g/m³ with a range of 10–23 g/m³. Indoor AH and RH were linearly correlated with outdoor AH when the air conditioning (AC) was off, suggesting that outdoor AH may be a good proxy of indoor humidity in the absence of AC. All indoor measurements were more strongly correlated with outdoor measurements as distance from the equator increased. Such correlations were weaker during the wet season, especially when AC was in operation. These correlations will provide insight for assessing the seasonality of respiratory viral infections using outdoor climate data, which is more widely available than indoor data, even though transmission of these diseases mainly occurs indoors.     

Particle‐associated polycyclic aromatic hydrocarbons in a representative urban location (indoor‐outdoor) from South Europe: Assessment of potential sources and cancer risk to humans

PM₁₀‐bound polycyclic aromatic hydrocarbons (PAHs) levels were monitored at urban locations (outdoor/indoor) within the city of Madrid between May 2017 and April 2018. Fourteen PAH congeners were measured, potential emission sources were identified as were potential carcinogenic risks. The ΣPAHs averaged 0.577 and 0.186 ng/m³ in outdoor and indoor air, with a high linear correlation per individual mean PAH and month. The largest contributors to the ΣPAHs were the high‐molecular‐weight PAHs. Principal component analysis‐multiple linear regression results showed that emissions from diesel and vehicular processes explained 27% and 23% of the total variance of outdoor and indoor air, while combustion processes accounted for 30% and 25% in ambient and indoor air, respectively. During the cold season, biomass burning plus coal and wood combustion were additional sources of outdoor emissions. The heavy‐, medium‐ and light‐molecular‐weight PAH originating from outdoor sources accounted for 72%, 80%, and ~60% of the indoor levels of the three respective PAH groups. Average BaP concentration was 0.029 and 0.016 ng/m³ in outdoor and indoor air, respectively. Estimated BaPeq concentration averaged 0.072, 0.035, and 0.027 ng/m³ for outdoor, indoor, and indoor‐generated individual PAH concentrations, respectively. The estimated carcinogenic risk falls within the range of acceptable risk targeted by the US‐EPA.     

Evaluation on potential for assessing indoor formaldehyde using biosensor system based on swimming behavior of Japanese medaka (oryzias latipes)

In order to develop an early-warning biosensor system for predicting the impact on health of long-term and low-level exposure to indoor chemical compounds, e.g. volatile organic compounds (VOCs), we evaluated the potential for assessing indoor air quality using the biosensor system based on the swimming behavior of Japanese medaka (oryzias latipes) as an indicator of indoor air quality in the beginning. As a technology to dissolve chemical compounds into water efficiently, a micro bubble generator was introduced. The test chemical was formaldehyde which is a representative of chemical compounds existing indoors. The result of the measuring solubility of formaldehyde was that formaldehyde concentration in water was raised to 0.12 mg/L when 1.0 mg/m³ of formaldehyde in air was bubbled for approximately 44 h. The correlation between the 0.1 mg/L of formaldehyde in water, which is roughly equivalent to 0.83 mg/m³ of formaldehyde in air, and the swimming activities of medaka was investigated. The fish showed abnormal behavior compared to one under a control treatment, e.g. the body movement distance decreased and the duration time near the upper water column increased significantly. It was verified that it is possible to detect concentrations of formaldehyde of 0.83 mg/m³ in indoor air using this proposed biosensor system.     

Quantification of Birch and Grass Pollen Allergens in Indoor Air

Abstract Birch and grass pollen grains as well as pollen-derived small particles appear as potent allergens in the outdoor air during spring and summer. The occurrence of pollen allergens in indoor air, however, has not been studied in depth due to lack of suitable sampling and analytical methods. Herein, a recently reported “direct on sampling filter estimation” (DOSAFE) technique ( Acevedo et al., 1998 ) has been validated for quantification of pollen allergens in indoor air using two school rooms and two office rooms as experimental models. Using DOSAFE and polyclonal antibodies against water extracts of pollen from Betula pendula and Phleum pratense L, we found that indoor air of school and office rooms carried substantial amounts of pollen allergens, expressed as SQ units, predominantly occurring as particles with smaller diameters than the pollen grains. In one school room the indoor air birch pollen allergen concentrations increased from 242 to 403 SQ units/m³ over the sampling period although the corresponding outdoor air concentrations decreased from 350 to 90 SQ units/m³. Electrostatic air cleaning in one office room reduced its grass pollen allergen concentrations by more than 95% to 0.02–0.34 SQ units/m³ as compared to the control room.     

The effect of ventilation on soiling by particles of outdoor and indoor origin in historical churches

The particle concentrations outside and inside two historical churches were monitored for at least ten months. The highest levels of outdoor concentrations were recorded in winter. This was caused by high levels of particle emissions from the burning of predominantly solid fuel for domestic heating in premises around the two churches monitored. These high levels of particle concentrations declined over the warmer periods of the year with the lowest concentrations occurring in the summer months. Owing to the marked winter–summer pattern for outdoor concentrations, the particles of outdoor origin accounted for 80%–90% of the overall indoor particle concentrations in the period of predominantly cold weather conditions (December to March) and for 50%–60% in the warm period (June to September). Reducing air exchange between the external space and the church interiors by keeping windows and doors closed had a limited effect on the reduction of average particle concentrations indoors (by less than 10%). A controlled air exchange system, which would increase the ventilation of a church when the particle concentration outdoors is lower than indoors and reduce ventilation when the outdoor air is polluted, would produce a further reduction of 10% in the indoor average particle concentration. The general conclusion is that the protection of the interiors of historical churches against soiling is primarily achieved by the improved particle filtering capacity of building envelopes and the gradual reduction of the overall outdoor particle concentration. Use of air cleaning systems with particle filtration may be a viable long-term option.     

Profiles and seasonal distribution of airborne fungi in indoor and outdoor environments at a French hospital

A one-year prospective survey of fungal air contamination was conducted in outdoor air and inside two haematological units of a French hospital. Air was sampled with a portable Air System Impactor. During this period of survey, the mean viable fungal load was 122.1 cfu/m³ in outdoor air samples, and 4.1 and 3.9 cfu/m³ in samples from adult and pediatric haematology units, respectively. In outdoor samples, Cladosporium was the dominant genus (55%) while in the clinical units, Penicillium sp. (23 to 25%), Aspergillus sp. (15 to 23%) and Bjerkandera adusta (11 to 13%) were the most frequently recovered airborne fungi. The outdoor fungal load was far higher in autumn (168 cfu/m³), spring (110 cfu/m³) and summer (138 cfu/m³) than in winter (49 cfu/m³). In indoor air, fungal concentrations were significantly lower in winter (2.7 to 3.1 cfu/m³) than in summer (4.2 to 5.0 cfu/m³) in both haematology units. In the outdoor environment, Penicillium sp. and Aspergillus sp. were more abundant in winter while the levels of Cladosporium were lowest during this season. In the haematological units, the presence of Aspergillus sp. was stable during the year (close to 20%), Bjerkandera sp. was particularly abundant in winter (close to 30%); levels of Penicillium sp. were highest in autumn while levels of Cladosporium sp. were highest in spring and summer.     

办公建筑中空调形式对室内外PM2.5浓度相关性的影响

室外PM2.5可通过新风及围护结构缝隙渗透至室内,室外PM2.5较高时尤为明显,结果导致室内空气中的PM2.5浓度上升。为了研究空调形式对室内外PM2.5浓度相关性的影响,在2015年夏季对重庆某办公建筑中采用不同空调形式的室内外PM2.5浓度进行了实测。实测结果发现:集中式空调、分体式空调和非空调房间室内外PM2.5浓度比变化范围分别为0.59~0.76、0.47~0.76、0.71~0.91。室内外PM2.5浓度相关性系数的排序为:集中式空调环境(0.94)非空调环境(0.92)分体式空调环境(0.77),研究结果表明,办公建筑的空调形式,对室内外PM2.5浓度的相关性有影响。