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PubMed2026

Breathing carcinogens: PM2.5 air pollution and lung cancer in never-smokers, a narrative review.

BACKGROUND AND OBJECTIVE: Lung cancer in never-smokers (LCINS) disproportionately affects women and younger individuals, and its incidence has increased over recent decades. Environmental respiratory hazards, such as particulate matter ≤2.5 µm (PM2.5), are associated with lung cancer incidence and mortality, but the mechanisms by which PM2.5 increases lung cancer susceptibility remain incompletely understood. This review summarizes the current evidence linking PM2.5 exposure to LCINS and identifies priorities for future research. METHODS: A narrative review was conducted using PubMed/MEDLINE to identify English-language studies published from 2000 through May 2026 using combinations of the terms "PM2.5", "fine particulate matter", "air pollution", "lung cancer", "never-smokers", "environmental respiratory hazards", "genomic alterations", and "tumor microenvironment". Additional relevant studies were identified through manual review of the reference lists of included articles. Studies were selected based on their relevance to the epidemiology, biological mechanisms, genomic and immune landscape, and clinical implications of PM2.5-associated LCINS, with emphasis on original investigations, high-quality reviews, and landmark publications. KEY CONTENT AND FINDINGS: PM2.5 exposure promotes inflammatory signaling, metabolic reprogramming, and tumor progression. Emerging evidence suggests that PM2.5 functions primarily as a tumor promoter rather than a direct mutagen and is associated with genomic and epigenetic alterations, more advanced disease, and worse survival following lung cancer diagnosis and surgical resection. LCINS also exhibits distinct molecular and immunologic characteristics with important implications for screening, molecular profiling, and targeted therapies. CONCLUSIONS: PM2.5 is an increasingly recognized contributor to lung carcinogenesis in never-smokers. Improved understanding of the biologic mechanisms linking environmental respiratory hazards to LCINS may inform future screening strategies, precision oncology approaches, and novel therapeutic targets for this growing and understudied patient population.

Fine particulate matter ≤2.5 µm in dia↗

PubMed1999

The PM2.5 and PM10 particles in urban areas of Taiwan.

This study conducted an atmospheric aerosol sampling to measure the PM10 (particles < 10 microns in aerodynamic diameter) and PM2.5 (particles < 2.5 microns in aerodynamic diameter) mass concentrations from October 1996 to June 1997 in northern (Taipei), central (Taichung) and southern (Kaohsiung), the three largest cities of Taiwan. Seventy-eight samples were obtained to measure the mass concentrations of PM10 and PM2.5 from nine sampling sites. According to those results, the PM10 mass concentrations in Taipei, Taichung and Kaohsiung were 42.19, 60.99 and 77.10 micrograms/m3, respectively. The corresponding PM2.5 mass concentrations were 23.09, 39.97 and 48.47 micrograms/m3, respectively. The PM2.5 fraction accounted for 61-67% of the PM10 mass in central and southern Taiwan, but was lower (54-59%) in northern Taiwan. Some samples in which the PM2.5 fraction was overwhelmingly dominant could reach as high as 80-95% of the PM10 mass. In addition, the PM2.5, PM10 levels and PM2.5/PM10-2.5 (particles with aerodynamic diameters ranging from 2.5 to 10 microns) ratios in metropolitan Taiwan significantly fluctuated from site-to-site and over time. Moreover, ambient daily PM2.5 and PM10-2.5 mass concentrations did not correlate well with each other at most of the sampling sites, indicated that they originated from different kinds of sources and emitted variedly over time.

Air Pollutants↗

PubMed2003

Identification of the major sources contributing to PM2.5 observed in Toronto.

The chemical composition of Toronto PM2.5 was measured daily from Feb 2000 to Feb 2001, and source apportionment was undertaken using positive matrix factorization (PMF). In Toronto, PM2.5 levels were influenced both by local urban activities and also by regional-scale transport. Although several PMF solutions were possible, an eight-source model for explaining the observed Toronto PM2.5 was found to provide realistic results and interesting insights into sources. The four main sources were coal combustion related to regional transport and secondary sulfate (26%), secondary nitrate related to both local and upwind sources of NOx and NH3 (36%), secondary organic aerosols (SOA) formed from a variety of precursor organic emissions (15%), and motor vehicle traffic (10%). The other detectable sources were road salt (winter) and three types of primary PM2.5 hypothesized to be associated with smelters, coal and oil combustion, industry, and local construction. Overall, motor vehicle-related emissions (including road salt and nitrate) were estimated to be responsible for about 40% of the PM2.5. In the summer, the SOA mass was estimated to contribute approximately 20% to the PM2.5. Inclusion of water-soluble, low-molecular-weight organic acids led to identification of this component, thus providing a significant improvement in PMF's ability to resolve sources. Without organic acid measurements the SOA portion of the observed PM2.5 was assigned to the secondary coal component, increasing its contribution and resulting in a source profile with an unrealistic amount of organic mass. This suggests that in the northeastern part of North America, there are physical and/or chemical processes that lead to close interaction between secondary organic and inorganic aerosols.

Aerosols↗

PubMed2001

On-road particulate matter (PM2.5 and PM10) emissions in the Sepulveda Tunnel, Los Angeles, California.

Total and speciated particulate matter (PM2.5 and PM10) emission factors from in-use vehicles were measured for a mixed light- (97.4% LD) and heavy-duty fleet (2.6% HD) in the Sepulveda Tunnel, Los Angeles, CA. Seventeen 1-h test runs were performed between July 23, 1996, and July 27, 1996. Emission factors were calculated from mass concentration measurements taken at the tunnel entrance and exit, the volume of airflow through the tunnel, and the number of vehicles passing through the 582 m long tunnel. For the mixed LD and HD fleet, PM2.5 emission factors in the Sepulveda Tunnel ranged from 0.016 (+/-0.007) to 0.115 (+/-0.019) g/vehicle-km traveled with an average of 0.052 (+/-0.027) g/vehicle.km. PM10 emission factors ranged from 0.030 (+/-0.009) to 0.131 (+/-0.024) g/vehicle. km with an average of 0.069 (+/-0.030) g/vehicle.km. The PM2.5 emission factor was approximately 74% of the PM10 factor. Speciated emission rates and chemical profiles for use in receptor modeling were also developed. PM2.5 was dominated by organic carbon (OC) (31.0 +/- 19.5%) and elemental carbon (EC) (48.5 +/- 20.5%) that together account for 79% (+/-24%) of the total emissions. Crustal elements (Fe, Mg, Al, Si, Ca, and Mn) contribute approximately 7.8%, and the ions Cl-, NO3-, NH3+, SO4(2-), and K+ together constitute another 9.8%. In the PM10 size fraction the particulate emissions were also dominated by OC (31 +/- 12%) and EC (35 +/- 13%). The third most prominent species was Fe (18.5 +/- 9.0%), which is greater than would be expected from purely geological sources. Other geological components (Mg, Al, Si, K, Ca, and Mn) accounted for an additional 12.6%. PM10 emission factors showed some dependence on vehicle speed, whereas PM2.5 did not. For test runs in which the average vehicle speed was 42.6 km/h a 1.7 times increase in PM10 emission factor was observed compared to those runs with an average vehicle speed of 72.6 km/h. Speciated emissions were similar. However, there is significantly greater mass attributable to geological material in the PM10, indicative of an increased contribution from resuspended road dust. The PM2.5 shows relatively good correlation with NOx emissions, which indicates that even at the low percent of HD vehicles, which emit significantly more NOx than LD vehicles, they may also have a significant impact on the PM2.5 levels.

Air Movements↗

PubMedDate not supplied

Indoor and outdoor PM2.5 and CO in high- and low-density Guatemalan villages.

Continuous particles less than 2.5 microm in diameter (PM2.5) and carbon monoxide (CO) were monitored during breakfast, lunch, and dinner in three high-density and four low-density villages near Quetzaltenango, Guatemala to help assess the viability of this region for a proposed respiratory health and stove intervention study. Approximately 15 homes were visited during each mealtime in each of the seven villages; in all, 98 homes were visited, with a sampling duration of 2-3 min per home per meal. For each village, a line (transect) was drawn on a village map along existing roads from one end of the village to the other; homes and between-home outside locations along the transect were monitored. Although the predominant stove type was the open fire, several other stoves, in various levels of disrepair, were observed frequently. The highest indoor concentrations of PM2.5 were observed in homes using the open fire (avg. = 5.31 mg/m3; SD=4.75 mg/m3) or equivalent, although homes using the plancha--indigenous wood-burning stove with chimney--also had measurements > 13.8 mg/m3, PM2.5 limit of detection. The highest indoor concentrations of CO were also observed in homes using the open fire (avg. = 22.9 ppm; SD = 28.1 ppm), with a maximum measurement of > 250 ppm. For both PM2.5 and CO, levels measured in homes with plancha, lorena, or open fire were significantly higher than levels taken in the street or in homes using a gas stove. The Spearman correlation coefficient between PM2.5 and CO for all data combined was 0.81, and ranged from 0.30 for the lorena to 0.68 for the plancha in homes using wood-fueled stoves. Although indoor PM2.5 and CO levels were not significantly different between high- and low-density villages, street-level PM2.5 (p = 0.002) and CO (p= 0.002), were significantly higher in the high - density villages. These data provide a useful picture of the pollution levels coming from a range of cooking stoves in various levels ofdisrepair, as well as a representation of how outdoor particle mass and CO levels vary from high- versus low-density villages.

Air Pollution, Indoor↗

PubMed2002

Estimation of ambient PM2.5 concentrations in Maryland and verification by measured values.

In 1997, Maryland had no available ambient Federal Reference Method data on particulate matter less than 2.5 microm in aerodynamic diameter (PM23), but did have annual ambient data for PM smaller than 10 microm (PM10) at 24 sites. The PM10 data were analyzed in conjunction with local annual and seasonal zip-code-level emission inventories and with speciated PM2.5 data from four nearby monitors in the IMPROVE network (located in the national parks, wildlife refuges, and wilderness areas) in an effort to estimate annual average and seasonal high PM2.5 concentrations at the 24 PM10 monitor sites operating from 1992 to 1996. All seasonal high concentrations were estimated to be below the 24-hr PM2.5 National Ambient Air Quality Standards (NAAQS) at the sites operating in Maryland between 1992 and 1996. The estimates also indicated that 12 monitor sites might exceed the 3-year annual average PM2.5 NAAQS of 15 microg/m3, but Maryland's air quality shows signs that it has been improving since 1992. The estimates also were compared with actual measurements after the PM2.5 monitor network was installed. The estimates were adequate for describing the chemical composition of the PM2.5, forecasting compliance status with the 24-hr and annual standards, and determining the spatial variations in PM2.5 across central Maryland.

Air Pollutants↗

PubMed2003

PM2.5 assessment in 21 European study centers of ECRHS II: Method and first winter results.

The follow-up of a cohort of adults from 29 European centers of the former European Community Respiratory Health Survey (ECRHS) I (1989-1992) will examine the long-term effects of exposure to ambient air pollution on the incidence, course, and prognosis of respiratory diseases, in particular asthma and decline in lung function. The purpose of this article is to describe the methodology and the European-wide quality control program for the collection of particles with 50% cut-off size of 2.5 microm aerodynamic diameter (PM2.5) in the ECRHS II and to present the PM2.5 results from the winter period 2000-2001. Because PM2.5 is not routinely monitored in Europe, we measured PM2.5 mass concentrations in 21 participating centers to estimate background exposure in these cities. A standardized protocol was developed using identical equipment in each center (U.S. Environmental Protection Agency Well Impactor Ninety-Six [WINS] and PQ167 from BGI, Inc.). Filters were weighed in a single central laboratory. Sampling was conducted for 7 days per month for a year. Winter mean PM2.5 mass concentrations (November 2000-February 2001) varied substantially, with Iceland reporting the lowest value (5 microg/m3) and northern Italy the highest (69 microg/m3). A standardized procedure appropriate for PM2.5 exposure assessment in a multicenter study was developed. We expect ECRHS II to have sufficient variation in exposure to assess long-term effects of air pollution in this cohort. Any bias caused by variation in the characteristics of the chosen monitoring location (e.g., proximity to traffic sources) will be addressed in later analyses. Given the homogenous spatial distribution of PM2.5, however, concentrations measured near traffic are not expected to differ substantially from those measured at urban background sites.

Air Pollutants↗

PubMed2003

Particulate matter in California: part 1--Intercomparison of several PM2.5, PM10-2.5, and PM10 monitoring networks.

It will be many years before the recently deployed network of fine particulate matter with an aerodynamic diameter less than 2.5 microm (PM2.5) Federal Reference Method (FRM) samplers produces information on nonattainment areas, trends, and source impacts. However, data on PM2.5 and its major constituents have been routinely collected in California for the past 20 years. The California Air Resources Board operated as many as 20 dichotomous (dichot) samplers for PM2.5 and coarse PM (PM10-2.5). The California Acid Deposition Monitoring Program (CADMP) collected 12-h-average PM2.5 and PM10 from 1988 to 1995 at ten urban and rural sites and 24-h-average PM2.5 at five urban sites since 1995. Beginning in 1994, the Children's Health Study collected 2-week averages of PM2.5 in 12 communities in southern California using the Two-Week Sampler (TWS). Comparisons of collocated samples establish relationships between the dichot, CADMP, and TWS samplers and the 82-site network of PM2.5 FRM samplers deployed since 1999 in California. PM mass data from the different monitoring programs have modest to high correlation to FRM mass data, fairly small systematic biases and negative proportional biases ranging from 7 to 22%. If the biases are taken into account, all of the programs should be considered comparable with the FRM program. Thus, historical data can be used to develop long-term PM trends in California.

Air Pollutants↗

PubMed2006

Concentrations of Ni and V, other heavy metals, arsenic, elemental and organic carbon in atmospheric fine particles (PM2.5) from Puerto Rico.

Fine atmospheric particulate PM2.5 (particles with diameters of < 2.5 microm) were sampled in an urban industrialized area--Guaynabo, Puerto Rico (Figure 1)--and in a reference less polluted site Fajardo, Puerto Rico--and analyzed for trace metals, and inorganic and organic elemental carbon. PM2.5 samples were collected from November 2000 to September 2001 using an Andersen Instruments RAAS2.5-400 for periods of 72 h. Metals analyzed were arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) by atomic absorption. Levels of elemental and organic carbon (EC/OC) were also determined. All metals analyzed, except for Fe, were significantly higher in PM2.5 from Guaynabo when compared to Fajardo. Average levels of PM2.5 in Guaynabo were 11.6 versus 8.5 microg/m3 in Fajardo. Average levels of EC were 1.5 and <0.14 microg/m3; and OC levels were 2.2 and < 1 microg/m3 for Guaynabo and Fajardo, respectively. Levels of Ni (17 ng/m3) and V (40 ng/m3) determined in PM2.5 from the Guaynabo area were high when compared to other cities, and these metals could be responsible for respiratory problems reported in the area. Multivariate analyses showed strong relationships in Guaynabo between Ni and V, PM2.5 and Fe and As and Cu and Pb. In Fajardo, the strongest associations were obtained between PM2.5 and Fe, Cd and V and Ni and Pb and Cu, these last three elements exhibiting an inverse relationship.

Air Pollution↗

PubMed2005

Exhaled nitric oxide in children with asthma and short-term PM2.5 exposure in Seattle.

The objective of this study was to evaluate associations between short-term (hourly) exposures to particulate matter with aerodynamic diameters < 2.5 microm (PM2.5) and the fractional concentration of nitric oxide in exhaled breath (FE(NO) in children with asthma participating in an intensive panel study in Seattle, Washington. The exposure data were collected with tapered element oscillation microbalance (TEOM) PM2.5 monitors operated by the local air agency at three sites in the Seattle area. FE(NO) is a marker of airway inflammation and is elevated in individuals with asthma. Previously, we reported that offline measurements of FE(NO) are associated with 24-hr average PM2.5 in a panel of 19 children with asthma in Seattle. In the present study using the same children, we used a polynomial distributed lag model to assess the association between hourly lags in PM2.5 exposure and FE(NO) levels. Our model controlled for age, ambient NO levels, temperature, relative humidity, and modification by use of inhaled corticosteroids. We found that FE(NO) was associated with hourly averages of PM2.5 up to 10-12 hr after exposure. The sum of the coefficients for the lag times associated with PM2.5 in the distributed lag model was 7.0 ppm FE(NO). The single-lag-model FE(NO) effect was 6.9 [95% confidence interval (CI), 3.4 to 10.6 ppb] for a 1-hr lag, 6.3 (95% CI, 2.6 to 9.9 ppb ) for a 4-hr lag, and 0.5 (95% CI, -1.1 to 2.1 ppb) for an 8-hr lag. These data provide new information concerning the lag structure between PM2.5 exposure and a respiratory health outcome in children with asthma.

Age Factors↗

PubMedDate not supplied

[Environmental PM2.5 levels and distance from a heavy traffic road in Ciudad Juarez, Chihuahua, Mexico].

OBJECTIVE: To assess PM2.5 levels at different distances from a heavy traffic road. MATERIAL AND METHODS: Daily measurements of PM2.5 were taken between August 26 and 30, 2002, at different distances from Tecnológico Avenue in Ciudad Juarez, Chihuahua, Mexico. Data analysis consisted of descriptive statistics for each distance and KruskalWallis and cross trend for ranks. RESULTS: We found a significantly decreasing trend of PM2.5 median levels with increasing distance from Tecnológico Avenue (p<0.001). At 100 m distance from the avenue, PM2.5 levels decreased by 9.5 microg/m3 (40.6%) when compared to median levels registered on the avenue. The results showed a highly significant negative correlation between PM2.5 measurements and the distance from the avenue (r=-0.70, n=20 and p=0.0005). CONCLUSIONS: PM2.5 median levels decreased significantly after 100 meters from heavy traffic roads. These results are of great relevance when assessing exposure to PM2.5 in epidemiological studies.

Air Pollutants↗

PubMed2026

The association between prenatal PM2.5 constituent exposure and gestational diabetes mellitus: Exploratory analysis of the potential modifying role of thyroid hormones.

The associations of PM2.5 constituents with blood glucose and GDM remain unclear, and the interplay between PM2.5 exposure and thyroid hormone levels in relation to GDM has not been well characterized. This retrospective cohort study included 1314 pregnant women with data collected through multiple methods. A generalized linear model analyzed PM2.5-glucose links, logistic regression assessed pollutant-GDM associations, and stratified analyses explored these relationships at different thyroid hormone levels. In the study population, first-trimester exposure to SO42- and BC correlated positively with FBG, as did PM2.5 and its components in the second trimester. First-trimester SO4²⁻ exposure (OR=1.26, 95% CI: 1.06, 1.51) and second-trimester exposures to PM2.5 (OR=1.67, 95% CI: 1.19, 2.35), NO3⁻ (OR=1.34, 95% CI: 1.06, 1.68), and NH4⁺ (OR=1.33, 95% CI: 1.06, 1.65) were associated with increased GDM risk. Stratified analyses showed that second-trimester BC and OM were positively correlated with FBG in the high-TSH and low-FT4 strata, respectively. In addition, first-trimester exposure to SO42- (high TSH: OR = 1.42, 95% CI: 1.10, 1.84; low FT4: OR = 1.35, 95% CI: 1.05, 1.74) and to PM2.5 (high TSH: OR = 1.93, 95% CI: 1.14, 3.27; low FT4: OR = 1.82, 95% CI: 1.46, 2.25) in the second trimester were associated with higher odds of GDM. These findings show that PM2.5 exposure was associated with glucose dysregulation and GDM in pregnant women differently by trimester and component. Across the separate TSH- and FT4-stratified analyses, women in the high-TSH and low-FT4 strata, respectively, appeared to show greater susceptibility to air pollution-related GDM. These subgroup findings should therefore be interpreted as exploratory and require validation in future studies.

Effect modification↗

PubMed2006

The mutagenic hazards of environmental PM2.5 in Turin.

Owing to the large number of natural and anthropogenic sources, particulate matter (PM) may present several physical and chemical patterns in different areas. The finer PM2.5 fraction, which is now widely but not routinely measured in Europe, is considered to be the alveolar fraction of the ambient particles. Annual and winter mean concentrations of PM2.5 substantially vary in Europe, with higher concentrations in the South. The aims of this work were to (a) measure the PM2.5 levels in Turin over a long period, (b) evaluate mutagenic activities of organic extracts containing this collected complex mixture using the Ames test and (c) determine the level of polycyclic aromatic hydrocarbons (PAHs) in order to identify important mutagens in ambient air. Sampling was carried out from November 2001 to December 2004. The monthly mean of PM2.5 was 48.76+/-24.12 microg/m3. From the beginning to the end of the sample period there was a decrease in gravimetric levels, with annual means of 54.10+/-29.77 microg/m3 in 2002; 42.48+/-15.73 microg/m3 in 2003 and 45.89+/-24.92 microg/m3 in 2004. Samples were tested for mutagenicity using Salmonella typhimurium strains TA98 and TA100, with and without S9 mix metabolic activation. A positive genotoxic response was observed for TA98, with and without metabolic activation. The measured PAHs monthly mean level was 8.24+/-6.30 ng/m3, with values ranging from 0.20 to 21.38 ng/m3 Seasonal variation of gravimetric, mutagenic and PAH values was significant. The Salmonella assay results statistically correlated to PM2.5 and PAHs levels, but sometimes the mutagenic potencies were rather different despite an equal concentration of pollutant. The results confirm the usefulness of this biological approach to detect genotoxic properties of sampled PM2.5 and they show the variability of the mutagenic properties of the airborne mixture over time.

Environmental Monitoring↗

PubMed2026

Quantifying the combined effects of semi-closed terrain and monsoon on PM2.5 and O3 pollution aggregation in the North China Plain.

The North China Plain (NCP) and its surrounding regions represent one of the key priority areas for air pollution control. As anthropogenic emissions decline significantly, the effect of terrain and meteorology on air pollution pattern has become increasingly prominent, particularly given the NCP's unique semi-closed terrain and East Asian monsoon dynamics. However, quantitative characterization of terrain-dominated blocking effects remains unexplored. Here we quantitatively assess the blocking effects of mountains and terrain-coupled meteorological factors on air pollutant dispersion. We find the NCP on the eastern side of the Taihang Mountains showed high PM2.5 and O3 pollution levels, with winter PM2.5 and summer O3 high-value zones showing opposite north-south aggregation patterns. PM2.5 and O3 concentrations were highest in plains, followed by platforms, hills, and finally mountains. Within the 120-km buffer zones of the typical mountains in the NCP and its surrounding regions, PM2.5 and O3 concentrations increased initially with altitude but then decreased markedly above a threshold altitude. Above the threshold altitude, mountain blocking effects became dominant. The effective blocking altitudes of typical mountains in the NCP and its surrounding regions ranged between 22 and 929 m for winter PM2.5 pollution, and between 19 and 1060 m for summer O3 pollution. The Terrain-Wind Close Index indicates that the terrain-coupled East Asian monsoon showed stronger blocking effects on PM2.5 dispersion in southern NCP during winter and on O3 diffusion in northern NCP during summer, matching observed high-pollution zones. This study offers key insights for regional joint air pollution mitigation strategies, as well as regional pollution assessment.

Particulate Matter↗

PubMed2005

PM2.5 chemical composition in Hong Kong: urban and regional variations.

Chemically speciated PM2.5 measurements were made at roadside, urban, and rural background sites in Hong Kong for 1 year during 2000/2001 to determine the spatial and temporal variations of PM2.5 mass and chemical composition in this highly populated region. Annual average PM2.5 concentrations at the urban and rural sites were 34.1 and 23.7 microg m(-3), respectively, approximately 50-100% higher than the United States' annual average National Ambient Air Quality Standard (NAAQS) of 15 microg m(-3). Daily PM2.5 concentrations exceeded the U.S. 24-h NAAQS of 65 microg m(-3) on 19 days, reaching 131+/-8 microg m(-3) at the roadside site on 02/28/2001. Carbonaceous aerosol is the largest contributor to PM2.5 mass (explaining 52-75% of PM2.5 mass at the two urban sites and 32% at the background site), followed by ammonium sulfate (ranging from 23% to 37% at the two urban sites and 51% at the background site). Ammonium sulfate and crustal concentrations showed more uniform spatial distributions, while the largest urban-rural contrasts found in carbonaceous aerosol (likely due to emissions from on-road gasoline and diesel vehicles). Marine influences accounted for 7% of the mass at the background site (more than twice as much as at the two urban sites). Ternary diagrams are utilized to illustrate the different spatial patterns.

Journal Article↗

PubMed1999

The characteristic study of TSP, PM2.5-10 and PM2.5 in the rural site of central Taiwan.

The total suspended particle (TSP), PM2.5-10 (aerodynamic diameter less than 10 microns) and PM2.5 concentration (aerodynamic diameter less than 2.5 microns) concentrations were sampled by PS-1 and Universal sampler on the roof (25 m) of the Medical and Engineering Building in the campus of Hungkuang Institute of Technology (HKIT) which is located at a height of 500 m on Da Du Mountain. The results indicated that average TSP, PM2.5-10 and PM2.5 concentrations are 0.42, 0.34 and 0.019 mg/m3 in the day time, respectively and are 0.32, 0.26 and 0.017 mg/m3 in the night time, respectively. The ratios of PM2.5-10/TSP were from 76% to 85% and from 50% to 91% for day and night period, respectively. It indicated that the major composition in the total suspended particles was PM2.5-10 in the rural site. The relationship between TSP and PM2.5-10 is TSP = 1.16PM2.5-10 + 0.027 and TSP = 1.01 PM2.5-10 + 0.058 in the day and night time, respectively. The correlation coefficient (R2) is 0.98 and 0.97 for day and night period, respectively. The relationship between PM2.5-10 and PM2.5 is PM2.5 = 0.0005PM2.5-10 + 0.019 and PM2.5 = 0.037PM2.5-10 + 0.0076 in the day and night period, respectively. The correlation coefficient (R2) is 3E-5 and 0.67 for day and night period, respectively. The relationships between TSP, PM2.5-10, PM2.5 particle concentrations and wind speed (R2) in the day time are 0.71, 0.64, 0.43, respectively and are 0.83, 0.79, 0.57, respectively in the night time. The proposed reasons are that there are more activities caused by people (students) and natural living animals which absorbed some of the particles during the day time. Thus, the correlation coefficients for the night time are better than those of day time. The particle size distributions are both bimodel in the day and night time. The major peaks in the day time appear in the particle diameter between 0.031-0.056 micron and 3.16-5.62 microns in the day period and appear between 0.017-0.031 micron and 1.78-3.16 microns in the night period. The results indicate that the particle size distribution in the day time tends to be of larger particle size mode than the night time.

Air Pollutants↗

PubMed2002

Comparison of black smoke and PM2.5 levels in indoor and outdoor environments of four European cities.

Recent studies on separated particle-size fractions highlight the health significance of particulate matter smaller than 2.5 microm (PM2.5), but gravimetric methods do not identify specific particle sources. Diesel exhaust particles (DEP) contain elemental carbon (EC), the dominant light-absorbing substance in the atmosphere. Black smoke (BS) is a measure for light absorption of PM and, thus, an alternative way to estimating EC concentrations, which may serve as a proxy for diesel exhaust emissions. We analyzed PM2.5 and BS data collected within the EXPOLIS study (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) in Athens, Basel, Helsinki, and Prague. 186 indoor/outdoor filter pairs were sampled and analyzed. PM2.5 and BS levels were lowest in Helsinki, moderate in Basel, and remarkably higher in Athens and Prague. In each city, Spearman correlation coefficients of indoor versus outdoor were higher for BS (range rspearman: 0.57-0.86) than for PM2.5 (0.05-0.69). In a BS linear regression model (all data), outdoor levels explained clearly more of indoor variation (86%) than in the corresponding PM2.5 model (59%). In conclusion, ambient BS seizes a health-relevant fraction of fine particles to which people are exposed indoors and outdoors and exposure to which can be assessed by monitoring outdoor concentrations. BS measured on PM2.5 filters can be recommended as a valid and cheap additional indicator in studies on combustion-related air pollution and health.

Air Pollutants↗

PubMed2000

Comparison of short-term variations (15-minute averages) in outdoor and indoor PM2.5 concentrations.

Measurements of 15-min average PM2.5 concentrations were made with a real-time light-scattering instrument at both outdoor (central monitoring sites in three communities) and indoor (residential) locations over two seasons in the Minneapolis-St. Paul metropolitan area. These data are used to examine within-day variability of PM2.5 concentrations indoors and outdoors, as well as matched indoor-to-outdoor (I/O) ratios. Concurrent gravimetric measurements of 24-hr average PM2.5 concentrations were also obtained as a way to compare real-time measures with this more traditional metric. Results indicate that (1) within-day variability for both indoor and outdoor 15-min average PM2.5 concentrations was substantial and comparable in magnitude to day-to-day variability for 24-hr average concentrations; (2) some residences exhibited substantial variability in indoor aerosol characteristics from one day to the next; (3) peak values for indoor short-term (15-min) average PM2.5 concentrations routinely exceeded 24-hr average outdoor values by factors of 3-4; and (4) relatively strong correlations existed between indoor and outdoor PM2.5 concentrations for both 24-hr and 15-min averages.

Activities of Daily Living↗