Metals In Airborne Particulate Matter Research Articles

Evaluation of Toxic Heavy Metals and Health Risk in Airborne Particulate Matter at Qassim region, Saudi Arabia

Particulate matter (PM) significantly influences air quality, visibility, climate change, the earth’s radiative balance, and human health. The significance of carrying out this investigation in its entirety is due to the small amount of data that has been collected and published in Qassim region (26.2078º N, 43.4837º E). Understanding the origins of PM and its chemical species in Qassim districts is advantageous for the purpose of identifying impacts on one’s health Characterization of pollution sources also will assist in the success of mitigation strategies and solve the issue of increased PM concentrations in outdoor areas. Therefore, this study described the physical and chemical properties of PM by measuring the PM1, PM2.5, and PM10 concentrations in Qassim’s central urban and rural areas. In urban Qassim, the average PM1, PM2.5, and PM10 concentrations were 12.23, 33.16, and 155.38 µg/m3, respectively. On the other hand, the average PM1, PM2.5, and PM10 concentrations reached 8.18, 23.03, and 93.57 µg/m3 in rural Qassim, respectively. The findings revealed that fine particle concentrations have risen over allowable levels due to dust storms. A total of 18 elements and 8 chemical compounds were determined and identified. The compound concentrations of Al2O3, SiO2, CaO, TiO2, K2O, BaO, MnO, Fe2O3 and the essential elements Sr, V, Al, Cu, Ca, Fe, Cr, As, Zr, K, Br, Ba, Pb, Mn, Ni, Zn, Rb and Ti were determined using XRF and XRD. The findings revealed that fine particle concentrations have risen over allowable levels due to dust storms. The main elements in the trace elements were Ca, Fe, Al, Sr, K, and Mg, indicating significant contributions from the soil (Ca, Fe, Al, Mg), as well as from industrial and vehicle emissions (Sr, Ca, Al, Fe, K). V, Cu, Zn, Cr, Ni, Pb, Sr, As, Mn and Br fall under the anthropogenic category of trace elements, while Al, S, Na, Mg, Rb, K, Zr, Ti, Fe, Mn, Sr, Y, Cr, Ca, Ni, Zn and Cu are obtained from the earth's crust. HIGHLIGHTS The study measured levels of toxic heavy metals in airborne particulate matter (PM) in the Qassim region of Saudi Arabia The results indicated that the concentrations PM were higher than the recommended guidelines set by the World Health Organization (WHO), which poses a potential health risk to the population The study suggests that the major sources of heavy metals in the Qassim region are from dust storms and anthropogenic activities such as industrial activities and traffic emissions The study highlights the importance of regular monitoring of heavy metals in PM and the need for effective pollution control measures to protect public health GRAPHICAL ABSTRACT

The Study of Airborne Particulate Matter in Dalnegorsk Town

Mines, quarries, dumps, and tailings are the sources of air pollution. In the Dalnegorsk District (Primorsky Krai, Russia), there are 20 polymetallic deposits. This study aimed to evaluate the particle size and material composition of ambient particulate matter (PM) in Dalnegorsk town and verify the influence of mining and chemical industry facilities on the composition of PM. Ambient particulates were analyzed in samples of snow cover and washout from vegetation (conifer tree needles). According to particle size distribution data, the relative content of particles with a diameter up to 10 microns (PM10) reaches 40% in three snow samples taken in the central part of the town. Among ore minerals, pyrite and arsenopyrite predominated in the samples. In addition, sphalerite, galena, cassiterite, and iron–chromium–nickel formations of various shapes were found in the studied particles. The presence of these metals in airborne PM can negatively affect the incidence rate of PM-associated diseases and the determination of their levels are very useful for air pollution prevention strategies.

Characteristics of fine particulate matter and volatile organic compounds in subway station offices in China

The air quality in subway station offices can greatly affect the health and comfort of metro staff. We characterized the air pollution in the offices of six subway stations by measuring the concentrations and composition of airborne fine particulate matter and volatile organic compounds in both summer and winter. We compared the findings by season, ventilation system type, platform screen door design, and station age. Concentrations of metals in airborne particulate matter were higher in metro station offices than in reference ambient air, with iron, manganese, and copper greatly exceeding their concentrations in ambient air. The concentrations of total volatile organic compounds exceeded national standard limits and ranged from 1027.63 to 1801.83 μg/m3. Operating the mechanical ventilation system in full fresh-air mode rather than primary air return mode reduced the concentrations of volatile organic compounds. These findings provide an assessment of pollutant characteristics in metro station offices and may be useful in formulating prevention and mitigation strategies for indoor air quality management.

On-line determination of soluble Zn content and size of the residual fraction in PM2.5 incubated in various aqueous media

Transition metals in airborne particulate matter, especially those with aerodynamic diameters no more than 2.5 μm (PM2.5), have attracted considerable attention due to their potential environmental and human health risks. However, determination of these potential risks requires comprehensive knowledge of their dissolution behavior and residual size in aqueous media. Herein, we describe an analytical method for on-line determination of the soluble fraction of Zn as a model transition metal and the size of residual PM2.5 using hollow fiber flow field-flow fractionation (HF5) coupled with UV–vis absorption spectroscopy and inductively coupled plasma optical emission spectroscopy. HF5 was directly applied on the incubated samples in pure water (PW), simulated natural water (SNW), and simulated lung fluid (SLF) due to its efficient in-line filtration and excellent fractionation resolution. Firstly, the potential of the proposed method (under optimized conditions) for size characterization was assessed against commercial silica microparticles, and results in good agreement with manufacturer and scanning electron microscopy values were obtained. The accuracy of quantification of soluble Zn in various media was then validated using a standard reference material in terms of satisfactory recoveries compared with the reference values. For the real PM2.5 samples collected from different sites in Beijing, China, the soluble Zn percentages in PW, SNW, and SLF were within 15.4–16.7%, 10.6–12.7%, and 43.1–46.9%, respectively, with the amount of particles smaller than ~10 nm released from PM2.5 increasing in the order of SNW < PW < SLF. The proposed HF5-based method provides a powerful and efficient tool for the quantification of soluble transition metal fractions and size characterization of residual particles with reduced analysis times, thus possessing great promise in real-time tracking of the transformation of PM2.5 in environmental and physiological media and in risk assessment.

Determination of oxoanions and water-soluble species of arsenic, selenium, antimony, vanadium, and chromium eluted in water from airborne fine particles (PM2.5): effect of acid and transition metal content of particles on heavy metal elution.

Heavy metals in particulate matter (PM) are of great concern, and their effects on the environment and human health depend on their solubilities and species present. In this study, the solubility of As, Se, Sb, V and Cr and their species eluted in water was investigated. As, Se, Sb, and V were present mostly in fine particles, and they were predominantly water-soluble in fine particles (<2.5 μm, PM2.5) but insoluble in coarse particles (>2.5 μm). Solubility of Cr was poor even in fine particles. It was found that for fine particles, solubilities of the heavy metals were related to the nitrate and sulfate contents. This suggests that the higher the acidity of the particles, the higher the solubility of the heavy metals. Oxoanions of the five kinds of heavy metals in water extracts of fine particles were determined by inductively coupled plasma mass spectrometry preceded by ion chromatography. The results suggested the presence of atmospheric oxidation during the aerosol transportation. Also, the As(iii)/As(v) (arsenite/arsenate) ratios for the fine particle extracts were related to the transition metal concentrations, which indicated that Fe, Cu, etc. in fine particles affected the As redox equilibrium. It was suggested that the heavy metals exist as complexes with iron hydroxide and dissolved organic matter in addition to the free oxoanions. These investigations were performed for PM samples collected in winter and summer in Kumamoto, west Japan, where the site is strongly exposed to westerly winds from continental East Asia. The obtained results improve our understanding of the behavior of the heavy metals in airborne PM after depositing on a wet environment and biota.

Associations between Personal Exposure to Metals in Fine Particulate Matter and Autonomic Nervous System Dysfunction among Healthy Adults

ABSTRACT The impact of airborne particulate matter and its metal components on autonomic nervous system (ANS) dysfunction in healthy subjects remains unclear. The aim of this study was to examine the effects of personal exposure to airborne particulate matter on the ANS in young, healthy adults. This longitudinal study recruited 82 adults aged 20 to 35 years from districts A and B. District A had lower ambient PM2.5 levels than district B. Personal exposure to fine particulate matter and metals in PM2.5 was collected every two months. The heart rate variability (HRV) indices of each participant were measured three times. The relationship among the PM2.5 concentration, metals in PM2.5 and HRV level was investigated by a generalized estimating equation with an autoregression of order 1. The average age of the participants was 26.4 ± 3.6 years in district A and 21.9 ± 1.5 years in district B (p < 0.001). After adjusting for covariables, significant changes in Log10 standard deviation of normal to normal (SDNN) intervals and Log10 square root of the mean of the sum of the squares of differences (r-MSSDs) were related to unit changes in Log10 iron in PM2.5 (β = –0.033, 95% CI = –0.060 to –0.0056, p < 0.05 and β = –0.041, 95% CI = –0.075 to –0.0076, p < 0.05, respectively). The Log10 SDNN levels were significantly positively related to Log10 gallium in PM2.5 (β = 0.054, 95% CI = 0.0064 to 0.10, p < 0.05). Exposure to heavy metals in airborne particulate matter was associated with ANS dysfunction.

Janus Electrochemical Paper-Based Analytical Devices for Metals Detection in Aerosol Samples.

Exposure to trace metals in airborne particulate matter (PM) has been linked to various adverse health effects. Quantifying metals in PM is important; however, current analytical tools tend to be bulky and expensive. A need therefore exists for more rapid, low-cost, portable tools for multiplexed determination of metals in PM. Electrochemical paper-based devices (ePADs) have been used for detecting metals in PM but require different devices and methods for different metals, making the systems more complicated than desired. Recently reported Janus ePADs offer a solution to this problem by allowing for multiple electrochemical experiments from a single sample. Here, we sought to determine if a Janus ePAD containing four independent channels and working electrodes could be used for simultaneous detection of multiple metals in PM. Online sample pretreatment in each channel during sample delivery yielded optimal conditions for each experiment. The design allows the device to conduct square-wave anodic stripping voltammetry (SWASV) and square-wave cathodic stripping voltammetry (SWCSV) for simultaneous detection of Cd, Pb, Cu, Fe, and Ni from a single sample. Two detection zones each with shared reference and counter electrodes were used for SWASV and SWCSV, respectively. The proposed sensors reached LODs down to 0.5, 0.5, 1.0, 0.5, and 1.0 μg L-1, for Cd(II), Pb(II), Cu(II), Fe(II), and Ni(II), respectively. The linear working ranges were 0.5-400.0 μg L-1 for Cd(II), Pb(II), and Fe(II), 1.0-400.0 μg L-1 for Cu(II), and 0.5-200.0 μg L-1 for Ni(II). The devices were applied for Cd(II), Pb(II), Cu(II), Fe(II), and Ni(II) determination in PM samples, and the results agreed with those using traditional ICP-MS analyses at 95% confidence.

Anthropogenic and meteorological influences on PM10 metal/semi-metal concentrations: Implications for human health.

There is growing interest in investigating the human health risk associated with metals in airborne particulate matter. The objective of this paper is the health risk assessment of Al, Be, Sb, Sn, Ti and Tl in PM10 under different advections of air masses. These metals/semi-metal were studied in samples collected in an area influenced by industrial activities in northern Spain with the aim of analysing the variations in PM10 metal/semi-metal. Elemental concentrations were assessed over a period of one year in terms of air mass origin by means of back trajectories (HYSPLIT), the conditional probability function, polar plots, PM concentration roses, aerosol maps (NAAPs) and receptor modelling. The mean concentrations of Al, Be, Sb, Sn, Ti and Tl were 254, 0.02, 1.30, 1.15, 15.3 and 0.20 ng/m3, respectively, and were within the usual range for suburban stations in Europe. The highest levels were recorded during conditions of regional air mass origin, highlighting the importance of sources not far from the station. Under these circumstances, the renovation of air masses was not produced. The main sources of metals were anthropogenic, mostly related to the use of coal and coke production. In general, the cancer and non-cancer risk values obtained in this study fell within accepted precautionary criteria in all trajectory groups. However, in order to improve air quality and reduce risks to human health, the impact resulting from the joint inhalation of Al, Be, Sb, Sn, Ti and Tl should not be ignored when air masses are fundamentally of regional origin.

Polyurethane Foam (PUF) Disk Samplers for Measuring Trace Metals in Ambient Air

A new method is presented for measuring atmospheric concentrations of trace metals in airborne particulate matter using polyurethane foam (PUF) disk passive air samplers (PUF-PASs) and passive dry ...

Multiplex quantification of metals in airborne particulate matter via smartphone and paper-based microfluidics

On-site spatial variation study of airborne trace metals has been known to be the key to providing a comprehensive evaluation of air pollution information at any targeted location. However, the existing portable approaches either do not allow sample analysis in the longitudinal direction or is not yet practically applicable due to due to the lack of a portable detection method. In this paper, by integrating paper based colorimetric detection via cellphone and unmanned aerial vehicle (UAV) in-air sampling, we present an approach for on-site multiaxial quantification of airborne trace metals in an arrayed format. Using a self-built sampler mounting on a UAV, our approach enables automatic, multiaxial air PM sampling. In addition, by relying only on a cellphone and a custom-made field reaction kit, samples collected in-air can be readily processed, detected in an arrayed format and interpreted on-site within 30 min. Finally, an ultrafast batch-to-batch paper microfluidic chip fabrication protocol enables 48 chips to be fabricated under 30 s at a cost of 1.92 $, making the approach well-suited for disposable on-site use. Our system was first calibrated for 6 metals commonly found in airborne PM (i.e. Co, Cu, Fe, Mn, Cr and Ni), and the corresponding metals detection limits were found to be 8.16, 45.84, 1.86 × 102, 10.08, 1.52 × 102 and 80.40 ng. The validity of our approach was then demonstrated by characterizing 6 metals commonly found in air PM using a certified ash sample, and the experimentally determined metal weight percentage showed a good agreement with the manufacture certified value. Finally, the approach was used for on-site airborne trace metals spatial variation study at 4 difference locations in Fuzhou City (China), thus demonstrating the significance of our approach in supplementing air pollution information gathering and progressing rapid, on-site air toxicity assessment research.

Portable detection of trace metals in airborne particulates and sediments via μPADs and smartphone.

Particulate matter (PM), a key indicator of air pollution by natural and anthropogenic activities, contributes to a wide spectrum of diseases that lead to a shortening of life expectancy. It has been recognized that trace metals in airborne PM are highly toxic and can be correlated with lesion in respiratory, gastrointestinal, immunological, and hematological systems. Traditional methods for trace metal assay require sophisticated instrumentations and highly trained operators in centralized laboratories. In this work, by integrating the technologies of microfluidic paper-based analytical devices, additive manufacturing, smartphone, and colorimetric sensing, we developed the first smartphone based paper microfluidic platform for portable, disposable, and quantitative measurements of cobalt (Co), copper (Cu), and iron (Fe) in ambient air and street sediments. On a single A4-sized paper, 48 devices were fabricated in under 30 s with a total cost of ∼$1.9. On each device, 12 reaction units were patterned and used for colorimetric tests. Particulate samples from urban ambient air and street sediments were collected, processed, and analyzed. Signals of the on-chip complexation product were recorded using a smartphone camera and processed by a self-developed app on an iOS system. For precisely controlling the object distance, chip position, and luminance, a hand-held 3D cellphone housing was designed and printed. The detection limits of Co, Cu, and Fe were determined to be 8.2, 45.8, and 186.0 ng, while the linear dynamic ranges were calculated to be 8.2-81.6, 45.8-4.58 × 102, and 1.86 × 102-1.86 × 103 ng, representing a practically relevant device performance with a significant reduction in the detection cost and time consumption. Trace metals in ambient air and sediments of two cities in China have been quantified portably, thus demonstrating the utility of our system in improving strategies for air pollution control in low-resource settings.

Investigation of Heavy Metals Content in Airborne Particles from Ploiesti, Romania

This study aims to evaluate the concentrations of heavy metals in airborne particulate matter (PM) collected in Ploiesti city (Romania) during the monitoring campaigns performed in 2015. Various health effects of airborne PM, from less serious to very serious ones, are often associated with its chemical speciation. The heavy metals bounded on PM may accumulate in human body by inhalation and can produce both short-term and long-term negative health effects especially in children and sensitive people. We investigated several heavy metals associated with PM2.5 collected in 12 relevant sampling points to estimate their potential impact on urban population health. PM samples were collected on 37 mm quartz fiberglass filters using a precision optical instrument i.e., DustTrak DRX8533EP. The deposition of elements on the surface of samples was determined using a scanning electron microscope (SEM). The analysis and quantification of trace elements were performed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The experiments indicated that samples of PM contained heavy metals in the following order Zn ] Ni ] Cr ] Pb ] As ] Cd. Monitoring of elemental composition in atmospheric particles can contribute to a better air quality management.

Determination of total and bioaccessible metals in airborne particulate matter from an urban and a rural area at Sarajevo

ABSTRACTAirborne particulate matter of up to 10 µm collected at an urban and a rural area at Sarajevo in 2013 and 2014 was acid digested for determination of total concentrations or extracted with synthetic gastric juice for the bioaccessible fractions of Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn and determined by graphite furnace and flame atomic absorption spectrometry. The total concentrations of Cr, Cu, Fe, Mn, Pb, and V were higher at the urban site, while those of Cd, Ni, and Zn were virtually equal at both sites. The average bioaccessible fractions exhibited the following trend at both sites: Fe > Zn > Cu > Mn > Pb > Cr > V > Ni > Cd. Enrichment factors and daily intake of metals by inhalation were calculated.

Determination of water soluble trace metals in airborne particulate matter using a dynamic extraction procedure with on-line inductively coupled plasma optical emission spectrometric detection

A novel continuous-flow system for the dynamic extraction of water soluble metal fractions in airborne particulate matter (APM) with subsequent inductively coupled plasma optical emission spectrometric (ICP-OES) analysis of derived extracts is presented. The fully automated extraction system with on-line multi-element detection offers enhanced sensitivity when compared to batch-wise counterparts; additionally it provides information about the extraction process. With the developed procedure detection limits in the order of 1.5 (Ba) to 8.0 (Ni)ng extractable mass per investigated sample could be achieved, which translates to method detection limits for soluble metal concentrations in APM ranging from 0.2ngm−3 (Ba) to 0.9ngm−3 (Fe). Reproducibility of analysis was determined by replicate measurement (n=6) of an APM sample with an aerodynamic diameter ≤10μm (PM10), derived results varied between 3.5% (Mn) and 12.1% (Ni) relative standard deviation. Method validation was accomplished by comparison of extracted soluble and remaining non-soluble fractions with the total metal contents of the investigated PM10 samples, showing an excellent mass balance for all elements. Application of the developed procedure for the analysis of water soluble metal fractions in PM10 samples (n=16) from Linz (Austria) indicated a high variability of extractable fractions ranging from 11.7±7.2% (Fe) to 48.8±15.4% (Mn) of the total metal contents.

Characteristics of heavy metals in airborne particulate matter on misty and clear days

This study identified characteristics of heavy metals in ambient total suspended particulates (TSP) and air pollutants (PM10, CO, NOx, SO2 and O3) collected on clear and misty days at an urban-residential area and an industrial area in the largest industrial city, Korea, for one-year study period. Average concentrations of TSP at the urban-residential (130μg/m3) and industrial (141μg/m3) areas on misty days were 1.9–2.1 (p<0.05) times higher than those on clear days. Concentrations of heavy metals in the TSP from both areas on misty days were significantly (p<0.05) higher than those on clear days. In particular, Pb and Mn concentrations on misty days were 2.4–2.6 (p<0.05) and 1.7–1.8 (p<0.05) times, respectively, higher at both areas as compared to clear days. Clear days showed higher correlations between TSP and heavy metal concentrations than on misty days at both areas. Average concentrations of PM10, CO and NO2 simultaneously measured at/near the sampling sites on misty days were significantly (p<0.05) higher than on clear days at both areas. Average O3 and SO2 concentrations showed a similar increase pattern at only one area.

Evaluation of airborne particulate matter and metals data in personal, indoor and outdoor environments using ED-XRF and ICP-MS and co-located duplicate samples

Factors and sources affecting measurement uncertainty associated with monitoring metals in airborne particulate matter (PM) were investigated as part of the Windsor, Ontario Exposure Assessment Study (WOEAS). The assessment was made using co-located duplicate samples and a comparison of two analytical approaches: ED-XRF and ICP-MS. Sampling variability was estimated using relative percent difference (RPD) of co-located duplicate samples. The comparison of ICP-MS and ED-XRF results yields very good correlations ( R 2 ≥ 0.7) for elements present at concentrations that pass both ICP-MS and ED-XRF detection limits (e.g. Fe, Mn, Zn, Pb and Cu). PM concentration ranges (median, sample number) of 24-h indoor PM 10 and personal PM 10 filters, and outdoor PM 2.5 filters were determined to be 2.2–40.7 (11.0, n = 48) μg m −3, 8.0–48.3 (11.9, n = 48) μg m −3, and 17.1–42.3 (21.6, n = 18) μg m −3, respectively. The gravimetric analytical results reveal that the variations in PM mass measurements for same-day sampling are insignificant compared to temporal or spatial variations: 92%, 100% and 96% of indoor, outdoor and personal duplicate samples, respectively, pass the quality criteria (RPD ≤ 20%). Uncertainties associated with ED-XRF elemental measurements of S, Ca, Mn, Fe and Zn for 24-h filter samples are low: 78%–100% of the duplicate samples passed the quality criteria. In the case of 24-h filter samples using ICP-MS, more elements passed the quality criteria due to the lower detection limits. These were: Li, Na, K, Ca, Si, Al, V, Fe, Mn, Co, Cu, Mo, Ag, Zn, Pb, As, Mg, Sb, Sn, Sr, Th, Ti, Tl, and U. Low air concentrations of metals (near or below instrumental detection limits) and/or inadvertent introduction of metal contamination are the main causes for excluding elements based on the pass/fail criteria. Uncertainty associated with elemental measurements must be assessed on an element-by-element basis.

Some metals in airborne particulate matter in Metro-Cebu (Philippines)

Some metals in airborne particulate matter in Metro-Cebu (Philippines)

Chemical fractionation of heavy metals in airborne particulate matter (PM10) by sequential extraction procedure

In this study, a series of 36 airborne particulate matter (PM10) samples were colleted over a 1 year period at an urban area–Tirupati, India. The samples were collected on paliflex-filters using Mini-Partisol air sampler equipped with PM10 inlet. A three stage sequential extraction procedure viz. environmentally mobile, bound to carbonates and oxides and bound to silicates and organic matter, was applied to heavy metals such as Pb, Cd, Zn, and Cu in PM10 samples. The heavy metals were determined by differential pulse anodic stripping voltammetry (DPASV). The reliability and applicability of the method was checked by using, NIST Standard Reference Material (SRM 1648). Good agreement was obtained between the total concentration of studied metals after three-step leaching procedure and certified values. Speciation results shows that higher percentage of Pb and Cd are accumulated in mobile fraction, where as higher amount of Cu and Zn was found in environmentally immobile fraction. Multivariate statistical analysis has been performed for the variables to define possible sources, and the results shows that mainly two sources, particles from traffic and particles from land were identified.

Monitoring personal, indoor, and outdoor exposures to metals in airborne particulate matter: Risk of contamination during sampling, handling and analysis

Rigorous sampling and quality assurance protocols are required for the reliable measurement of personal, indoor and outdoor exposures to metals in fine particulate matter (PM 2.5). Testing of five co-located replicate air samplers assisted in identifying and quantifying sources of contamination of filters in the laboratory and in the field. A field pilot study was conducted in Windsor, Ont., Canada to ascertain the actual range of metal content that may be obtained on filter samples using low-flow (4 L min −1) 24-h monitoring of personal, indoor and outdoor air. Laboratory filter blanks and NIST certified reference materials were used to assess contamination, instrument performance, accuracy and precision of the metals determination. The results show that there is a high risk of introducing metal contamination during all stages of sampling, handling and analysis, and that sources and magnitude of contamination vary widely from element to element. Due to the very small particle masses collected on low-flow 24-h filter samples (median 0.107 mg for a sample volume of approximately 6 m 3) the contribution of metals from contamination commonly exceeds the content of the airborne particles being sampled. Thus, the use of field blanks to ascertain the magnitude and variability of contamination is critical to determine whether or not a given element should be reported. The results of this study were incorporated into standard operating procedures for a large multiyear personal, indoor and outdoor air monitoring campaign in Windsor.

Heavy Metals in Airborne Particulate Matter of Urban Coimbatore

Exposures to airborne metals are known to cause physiological responses in organisms and wide-ranging health effects in humans. Hence determination of metals in particulate matter is important from a toxicological perspective. In the current study heavy metals associated with respirable (RSPM) and nonrespirable (NRSPM) fractions of suspended particulate matter were estimated in air samples from six stations in Coimbatore, India, during March 1999 to February 2001. The mean quantity of heavy metals in RSPM was in the order Zn > Cu > Pb > Ni > Cr > Cd. Concentrations of these heavy metals were in the range of BDL (below detectable level) to 2,147 ng/m3 in RSPM. The highest level of lead (2,147 ng/m(3)) was recorded at an industrial station. The station also had the highest mean value (481 +/- 544.3 ng/m(3)), suggesting the importance of industrial operations in determining the ambient concentrations of lead. Significant positive correlation among metals excepting lead and copper suggests that they originate mostly from a common source. Air samples of urban and industrial areas showed higher concentrations than residential (Urban) and suburban areas.