Feasibility of Collecting Saliva for Biological Verification of Tobacco Use Status in Dental Practices and Patients' Homes: Results from the National Dental PBRN.

OBJECTIVE: To evaluate the feasibility of collecting and analyzing saliva samples from dental practices and patients' homes for biochemical verification of tobacco use status. BASIC RESEARCH DESIGN: Sub-study within single-arm, multi-center, longitudinal clinical study. CLINICAL SETTING: Dental practices in the South Central region of the United States National Dental Practice-Based Research Network and patients' homes. PARTICIPANTS: Fifty-five patients recruited from 30 dental practices. INTERVENTIONS: Participants in the sub-study were instructed on saliva collection for cotinine analysis in dental practices where they enrolled in the primary study. Saliva was collected at the practices and then from patients' homes. MAIN OUTCOME MEASURES: Feasibility for dental practice collection was define as 80% of enrolled participants having analyzable samples. For patients' home collection, feasibility was defined as 70%. RESULTS: Forty-seven samples (i.e., 86% of those enrolled) collected in dental practices were analyzable. Twenty-one samples (i.e. 38% of those enrolled) collected in patients' homes were analyzable. CONCLUSIONS: Collecting saliva samples for cotinine analysis from dental practices, but not from patients' homes, was feasible. Dental practices may provide an advantageous setting for biochemically verifying tobacco use status as part of clinical trials for tobacco cessation.

Use of psychotropic drugs during pregnancy and breast-feeding.

OBJECTIVE: To write clinical guidelines for the use of psychotropic drugs during pregnancy and breast-feeding for daily practice in psychiatry, obstetrics and paediatrics. METHOD: As we wanted a guideline with a high degree of consensus among health professionals treating pregnant women with a psychiatric disease, we asked the Danish Psychiatric Society, the Danish Society of Obstetrics and Gynecology, the Danish Paediatric Society and the Danish Society of Clinical Pharmacology to appoint members for the working group. A comprehensive review of the literature was hereafter conducted. RESULTS: Sertraline and citalopram are first-line treatment among selective serotonin reuptake inhibitor for depression. It is recommended to use lithium for bipolar disorders if an overall assessment finds an indication for mood-stabilizing treatment during pregnancy. Lamotrigine can be used. Valproate and carbamazepin are contraindicated. Olanzapine, risperidone, quetiapine and clozapine can be used for bipolar disorders and schizophrenia. CONCLUSION: It is important that health professionals treating fertile women with a psychiatric disease discuss whether psychotropic drugs are needed during pregnancy and how it has to be administered.

A Nordic survey on artificial intelligence in the radiography profession - Is the profession ready for a culture change?

INTRODUCTION: The impact of artificial intelligence (AI) on the radiography profession remains uncertain. Although AI has been increasingly used in clinical radiography, the perspectives of the radiography professionals in Nordic countries have yet to be examined. The primary aim was to examine views of Nordic radiographers 'on AI, with focus on perspectives, engagement, and knowledge of AI. METHODS: Radiographers from Denmark, Norway, Sweden, Iceland, Greenland, and the Faroe Island were invited through social media platforms to participate in an online survey from March to June 2023. The survey encompassed 29-items and included 4 sections a) demographics, b) barriers and enablers on AI, c) perspectives and experiences of AI and d) knowledge of AI in radiography. Edgars Schein's model of organizational culture was employed to analyse Nordic radiographers' perspectives on AI. RESULTS: Overall, a total of 421 respondents participated in the survey. A majority were positive/somewhat positive towards AI in radiography e.g., 77.9 % (n = 342) thought that AI would have a positive effect on the profession, and 26% thought that AI would reduce the administrative workload. Most radiographers agreed or strongly agreed that clinicians may have access to AI generated reports (76.8 %, n = 297). Nevertheless, a total of 86 (20.1%) agree or somewhat agreed that AI a potential risk for radiography. CONCLUSION: Nordic radiographers are generally positive towards AI, yet uncertainties regarding its implementation persist. The findings underscore the importance of understanding these challenges for the responsible integration of AI systems. Carefully weighing the expected influence of AI against key incentives will support a seamless integration of AI for the benefit not just of the patients, but also of the radiography profession. IMPLICATIONS FOR PRACTICE: Understanding incentives factors and barriers can help address uncertainties during implementation of AI in clinical practice.

Nordic radiographers' and students' perspectives on artificial intelligence - A cross-sectional online survey.

INTRODUCTION: The integration of artificial intelligence (AI) into the domain of radiography holds substantial potential in various aspects including workflow efficiency, image processing, patient positioning, and quality assurance. The successful implementation of AI within a Radiology department necessitates the participation of key stakeholders, particularly radiographers. The study aimed to provide a comprehensive investigation about Nordic radiographers' perspectives and attitudes towards AI in radiography. METHODS: An online 29-item survey was distributed via social media platforms to Nordic students and radiographers working in Denmark, Norway, Sweden, Iceland, Greenland, and the Faroe Islands including items on demographics, specialization, educational background, place of work and perspectives and knowledge on AI. The items were a mix of closed-type and scaled questions, with the option for free-text responses when relevant. RESULTS: The survey received responses from all Nordic countries with 586 respondents, 26.8% males, 72.1% females, and 1.1% non-binary/self-defined or preferred not to say. The mean age was 37.2 with a standard deviation (SD) of ±12.1 years, and the mean number of years since qualification was 14.2 SD ± 10.3 years. A total of 43% (n = 254) of the respondents had not received any AI training in clinical practice. Whereas 13% (n = 76) had received AI during radiography undergrad training. A total of 77.9% (n = 412) expressed interest in pursuing AI education. The majority of respondents were aware of the potential use of AI (n = 485, 82.8%) and 39.1% (n = 204) had no reservations about AI. CONCLUSION: Overall, this study found that Nordic radiographers have a positive attitude toward AI. Very limited training or education has been provided to the radiographers. Especially since 82.8% reports on plans to implement AI in clinical practice. In general, awareness of AI applications is high, but the educational level is low for Nordic radiographers. IMPLICATION FOR PRACTICE: This study emphasises the favourable view of AI held by students and Nordic radiographers. However, there is a need for continuous professional development to facilitate the implementation and effective utilization of AI tools within the field of radiography.

Functional implications of corticospinal tract impairment on gait after spinal cord injury.

OBJECTIVE: Maximum toe elevation during walking is an objective measure of foot drop and reflects the impairment of the corticospinal tract (CST) in persons with spinal cord injury (SCI). To determine if this measurement is functionally relevant to ambulatory abilities, we correlated maximum toe elevation with clinical physiotherapy tests. SETTING: Cross-sectional study, laboratory and clinical settings. METHODS: A total of 24 individuals with SCI (American Spinal Injury Association (ASIA) Impairment Scale D) were recruited. Maximum toe elevation during the swing phase of treadmill gait was measured with a kinematic system. CST function was assessed in a sitting position by measuring the motor-evoked potentials (MEPs) induced in tibialis anterior muscle with transcranial magnetic stimulation over the motor cortex. Clinical tests performed were 10-m and 6-min walk test (6MWT), Timed-Up and Go (TUG), Walking Index for Spinal Cord Injury, Berg Balance Scale, Lower Extremity Motor Score (LEMS) and sensory score of the L4, L5 and S1 dermatomes. RESULTS: Participants with lower toe elevation during gait walked at a slower speed, took more time to perform the TUG test, and covered a shorter distance in the 6MWT. They also scored lower on the LEMS and showed impaired superficial sensitivity of the dermatomes around the ankles. Few correlations were observed between CST function and clinical tests, but the presence of MEP at rest was indicative of faster speed and longer distance in the 6MWT. CONCLUSION: These results indicate that maximum toe elevation, which is directly correlated with CST impairment, is functionally relevant as it also correlates with timed clinical tests, LEMS and sensory scores.

Short report: Self-compassion and satisfaction with life in Danish adolescents with Developmental Language Disorder (DLD): `We are all in the same boat´.

BACKGROUND: Adolescents with Developmental Language Disorder (DLD) are at risk of emotional health problems and low self-esteem. However, little is known about their self-compassion (SC) and satisfaction with life (SWL). The present study compared self-compassion and satisfaction with life reported by Danish adolescents with DLD compared to typically developing (TD) peers, and whether severity of language difficulty is associated with SC and SWL. METHODS: Results were obtained from 10 Danish adolescents with DLD compared with 14 age-matched TD adolescents and 132 TD peers, aged 15 years. RESULTS: For SC and SWL results showed that adolescents with DLD reported more positive feelings compared to the TD adolescents. Interestingly for SC, the negative, but not the positive, domain differentiated the two groups, as adolescents with DLD reported less symptoms on self-judgment, isolation and overidentification. SC and SWL was strongly correlated with language abilities for the DLD group, but not for the TD group. CONCLUSIONS: Results from our pilot study showed that Danish adolescents with DLD reported being less harsh on themselves. Language abilities were associated with self-compassion for the DLD, but not for the TD group. Whether these group differences are due to environmental factors such as the specific Danish school setting of the DLD group or internal factors are discussed and requires further research.

Workplace factors facilitating the radiographers' assessment of referrals for diagnostic imaging - A qualitative study.

INTRODUCTION: Radiology referrals are assessed for appropriate imaging based on the available clinical information. The task is legally the responsibility of the radiologists but could be delegated to radiographers under guidance. Knowledge of how this task is organised in radiology departments is limited. The study aim was to identify workplace factors facilitating the radiographers' assessment of referrals for medical imaging. METHODS: Five radiographers were recruited by convenience- and snowball-sampling techniques through the online social media platform LinkedIn. The participants represented different private and public hospitals and had from three to above ten years of experience with assessment of referrals for plain and cross sectional imaging. Following a qualitative approach, 60-min in-depth semi-structured interviews were conducted through online video meetings. Interviews followed a topic guide with 15 questions and 20 keywords, previously tested through a pilot interview. Systematic text condensation was performed using NVivo 12, where central themes and underlying subthemes were developed. RESULTS: Five central facilitating factors were identified, each with subthemes identified as: (1) Formal responsibilities; Documented delegation, Specific role description, (2) Training; Achieving skills, Maintaining skills, (3) Guidelines; Clinical indications, Priority, (4) Resource allocation; Time, Staff, (5) a Supporting environment; Teamwork, Mutual benefits, Feedback and knowledge sharing. CONCLUSION: The study adds new and valuable insights into workplace factors facilitating the radiographers' delegated task of assessing referrals. Workflows adapting such factors benefit radiographers by increasing knowledge and professional development, while positively re-allocating radiologist resources. IMPLICATIONS FOR PRACTICE: The study findings may support radiology workplaces in establishing or improving referral assessment by radiographers. Subsequently, improved quality of patient services may be achieved.

Target structure induced suppression of the ionization cross section for very low energy antiproton-hydrogen collisions.

Low energy antiprotons have been used previously to give benchmark data for theories of atomic collisions. Here we present measurements of the cross section for single, nondissociative ionization of molecular hydrogen for impact of antiprotons with kinetic energies in the range 2-11 keV, i.e., in the velocity interval of 0.3-0.65 a.u. We find a cross section which is proportional to the projectile velocity, which is quite unlike the behavior of corresponding atomic cross sections, and which has never previously been observed experimentally.

Determination of material emission signatures by PTR-MS and their correlations with odor assessments by human subjects.

UNLABELLED: The objectives of this study were to determine volatile organic compound (VOC) emission signatures of nine typical building materials by using proton transfer reaction-mass spectrometry (PTR-MS) and to explore the correlation between the PTR-MS measurements and the measurements of acceptability by human subjects. VOC emissions from each material were measured in a 50-l small-scale chamber. Chamber air was sampled by PTR-MS to determine emission signatures. Sorbent tube sampling and TD-GC/MS analysis were also performed to identify the major VOCs emitted and to compare the resulting data with the PTR-MS emission signatures. The data on the acceptability of air quality assessed by human subjects were obtained from a previous experimental study in which the emissions from the same batch of materials were determined under the same area-specific ventilation rates as in the case of the measurements with PTR-MS. Results show that PTR-MS can be an effective tool for establishing VOC emission signatures of material types and that there were reasonable correlations between the PTR-MS measurements and the acceptability of air quality for the nine materials tested when the sum of selected major individual VOC odor indices was used to represent the emission level measured by PTR-MS. PRACTICAL IMPLICATIONS: The study shows that unique emission patterns may exist for different types of building materials. These patterns, or signatures, can be established by using PTR-MS, an online monitoring device. The sum of selected major individual VOC odor indices determined by PTR-MS correlates well with the acceptability of air quality assessed by human subjects, and hence provides a feasible approach to assessing perceived indoor air quality. This online assessment will open a new gate in understanding the role of VOC emissions from building materials on perceived air quality, forming a good foundation to develop real-time or near real-time methods for standard material emission testing and labeling, quality control of emissions from materials, and assessing the acceptability of air quality in buildings.

Availability of HIV-related health services in adolescent substance abuse treatment programs.

Given that alcohol and drug abuse heightens the risk of adolescents acquiring HIV, substance abuse treatment programs for youths may represent an important site of HIV prevention. In this research, we explored the adoption of three HIV-related health services: risk assessment during intake, HIV prevention programing, and HIV testing. Data were collection through telephone interviews with 149 managers of adolescent-only substance abuse treatment programs in the USA. About half of these programs had adopted HIV risk assessment and HIV prevention. On-site HIV testing was less widely adopted, with only one in four programs offering this service. At the bivariate level, the availability of on-site primary medical care and the availability of an overnight level of care were positively associated with these three types of services. The association for the measure of an overnight level of care was no longer significant once medical services were controlled. However, in a separate analysis, it was found that programs offering an overnight level of care were much more likely to offer on-site medical care than outpatient-only facilities. There was also evidence that publicly funded treatment programs were more likely to offer HIV prevention and on-site HIV testing, after controlling for other organizational characteristics. Much more research about the adoption of HIV-related services in adolescent substance abuse treatment is needed, particularly to offer greater insight into why certain types of organizations are more likely to adopt these health services.

Use of thermal desorption gas chromatography-olfactometry/mass spectrometry for the comparison of identified and unidentified odor active compounds emitted from building products containing linseed oil.

The emission of odor active volatile organic compounds (VOCs) from a floor oil based on linseed oil, the linseed oil itself and a low-odor linseed oil was investigated by thermal desorption gas chromatography combined with olfactometry and mass spectrometry (TD-GC-O/MS). The oils were applied to filters and conditioned in the micro emission cell, FLEC, for 1-3days at ambient temperature, an air exchange rate of 26.9h(-1) and a 30% relative humidity. These conditions resulted in dynamic headspace concentrations and composition of the odor active VOCs that may be similar to real indoor setting. Emission samples for TD-GC-O/MS analysis from the FLEC were on Tenax TA. Although many volatile VOCs were detected by MS, only the odor active VOCs are reported here. In total, 142 odor active VOCs were detected in the emissions from the oils. About 50 of the odor active VOCs were identified or tentatively identified by GC-MS. While 92 VOCs were detected from the oil used in the floor oil, only 13 were detected in the low-odor linseed oil. The major odor active VOCs were aldehydes and carboxylic acids. Spearmen rank correlation of the GC-O profiles showed that the odor profile of the linseed oil likely influenced the odor profile of the floor oil based on this linseed oil.

Tissue microarrays compared with whole sections and biochemical analyses. A subgroup analysis of DBCG 82 b&c.

INTRODUCTION: The tissue microarray (TMA) technique comprises the potential of significantly reducing time and tissue spent on slicing and performing immunohistochemical (IHC) stainings of paraffin-embedded tumor tissue. Tissue heterogeneity is an argument against using TMAs, which has been dealt with by increasing the size and number of cores punched from each tumor. No consensus exists on the most optimal size, number, and position of TMA cores in the donor paraffin block and no information exist regarding agreement between TMA cores from two different paraffin blocks from the same tumor or between TMA cores and biochemical analyses. PATIENTS AND METHODS: A central and a peripheral 1mm core and a whole section from each of 54 paraffin blocks from 27 breast cancers included in a one-institution cohort, and a single 1mm central TMA core, from each breast tumor from 1000 patients included in the DBCG82 b&c trials, were IHC stained for ER, PgR and HER2. In addition, ER and PgR were measured in the DBCG82 b&c trials by a biochemical analysis. Statistical analyses included Kappa statistics, Kaplan-Meier survival curves, Log-rank tests, and Cox regression hazards analyses. RESULTS AND CONCLUSION: IHC stainings for ER, PgR, and HER2 showed a substantial agreement between a single 1mm TMA core and the corresponding whole section, between central and peripheral cores, and between cores from two different paraffin blocks from the same tumor. In addition, a fine agreement was found for ER and PgR between IHC stainings of TMA cores and biochemical analyses. Divergence between IHC and biochemical analyses was predominantly due to the chosen thresholds. IHC staining of one 1mm core from each tumor revealed a significant independent prognostic value of PgR and HER2 on overall survival. In conclusion, IHC stainings for ER, PgR, and HER2 of just a single 1mm TMA core seems to be sufficient, as no significant heterogeneity was noticed.

Impact of BCL2 and p53 on postmastectomy radiotherapy response in high-risk breast cancer. A subgroup analysis of DBCG82 b&c.

PURPOSE: To examine p53 and BCL2 expression in high-risk breast cancer patients randomized to postmastectomy radiotherapy (PMRT). PATIENTS AND METHODS: The present analysis included 1 000 of 3 083 high-risk breast cancer patients randomly assigned to PMRT in the DBCG82 b&c studies. Tissue microarray sections were stained with immunohistochemistry for p53 and BCL2. Median potential follow-up was 17 years. Clinical endpoints were locoregional recurrence (LRR), distant metastases (DM), overall mortality, and overall survival (OS). Statistical analyses included Kappa statistics, chi(2) or exact tests, Kaplan-Meier probability plots, Log-rank test, and Cox univariate and multivariate regression analyses. RESULTS: p53 accumulation was not significantly associated with increased overall mortality, DM or LRR probability in univariate or multivariate Cox regression analyses. Kaplan-Meier probability plots showed reduced OS and improved DM and LRR probabilities after PMRT within subgroups of both p53 negative and p53 positive patients. Negative BCL2 expression was significantly associated with increased overall mortality, DM and LRR probability in multivariate Cox regression analyses. Kaplan-Meier probability plots showed a significantly improved overall survival after PMRT for the BCL2 positive subgroup, whereas practically no survival improvement was seen after PMRT for the BCL2 negative subgroup. In multivariate analysis of OS, however, no significant interaction was found between BCL2 and randomization status. Significant reductions in LRR probability after PMRT were recorded within both the BCL2 positive and BCL2 negative subgroups. CONCLUSION: p53 was not associated with survival after radiotherapy in high-risk breast cancer, but BCL2 might be.

The antiproton depth-dose curve in water.

We have measured the depth-dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge for ion recombination effects. The results are compared with Monte Carlo calculations and were found to be in good agreement. Based on this agreement we calculate the antiproton depth-dose curve for antiprotons and compare it with that for protons and find a doubling of the physical dose in the peak region for antiprotons.

CD34+ megakaryoblastic leukaemic cells are CD38-, but CD61+ and glycophorin A+: improved criteria for diagnosis of AML-M7?

The aim of this flow cytometry study in acute megakaryoblastic leukaemia (AML-M7) was to describe the membrane phenotype of CD34+ progenitor subsets and compare these with the phenotypes expressed by other AML FAB types. Following conventional histopathological diagnosis mononuclear cells from bone marrow and blood were examined in seven patients with AML-M7 and compared with results from 26 sequential patients with AML-M0 to AML-M6. The CD34+ subsets in AML-M7 patients differed from that of patients with AML-M0 to AML-M6 as the CD34+ CD61+ and the CD34+ Glycophorin A+ subsets were median 31% and 20%, respectively, compared to 4% and 2% in the AML-M0 to AML-M6 (P = 0.0005). Only 1% of the CD34+ progenitors were CD34+ CD38+ in AML-M7 compared to 72% in other AML subtypes (P < 0.000). These findings suggest that the CD34+ cell compartment in AML-M7 consists of early lineage-specific progenitors. In conclusion, flow cytometry analysis of CD34+ subsets may improve the diagnostic safety in AML-M7 and consequently the prognostic significance of immunophenotyping in acute leukaemia.

Expression of the intercellular adhesion molecule-3 (ICAM-3) in human renal tissue with relation to kidney transplants and various inflammatory diseases.

Adhesion molecules are important for immune regulatory mechanisms concerning antigen presentation, lymphocyte activation, localisation and migration as well as effector-target cell interactions in inflammatory processes. The immunohistochemical expression of ICAM-3, a recently cloned new member of the immunoglobulin family which also binds leucocyte function antigen 1 (LFA-1), was examined in 80 needle core biopsies from 35 renal allografts, 7 patients with mesangioproliferative glomerulonephritis, 5 patients with extracapillary glomerulonephritis, 4 patients with interstitial nephritis and 5 patients with diabetic nephropathy and 20 normal kidneys. In all types of lesions ICAM-3 was constitutively expressed on the majority of infiltrating leucocytes without detectable upregulation or presentation on possible target structures during inflammation indicating its possible role to be mainly in initiation of the inflammatory response.

Short-term in vivo priming of bone marrow haematopoiesis with rhG-CSF, rhGM-CSF or rhIL-3 before marrow harvest expands myelopoiesis but does not improve engraftment capability.

In an attempt to optimize bone marrow grafts for autologous transplantation 37 sequential patients suffering from various haematological diseases were treated with either recombinant human granulocyte colony-stimulating factor (rhG-CSF) (n = 23) or granulocyte-macrophage CSF (rhGM-CSF) (n = 8) for 5 days or interleukin 3 (rhIL-3) (n = 6) for 10 days before marrow harvest. All patients were in marrow remission at study entry. In contrast to rhIL-3, the administration of rhG-CSF or rhGM-CSF caused a significant (P < 0.01) increase in blood absolute neutrophil count. An increased marrow cellularity and a rise in the myeloid:-erythroid ratio was seen in the majority of patients during therapy, and in the rhIL-3 treated group a rise in the number of megakaryocytes and increased marrow fibrosis was seen in most patients. Moreover, a median of 2-, 5- and 10-fold increase in myeloid progenitors was the result of short-term administration of rhIL-3, rhGM-CSF and rhG-CSF, respectively. However, transplantation performed with primed expanded marrow grafts did not significantly reduce the time to myeloid regeneration when compared to historical controls. In conclusion, the results demonstrate that short-term priming with haematopoietic cytokines before autologous bone marrow stem cell harvest is a safe procedure which effectively expands marrow haematopoisis without enhanced engraftment capability.

Membrane ion-exchange chromatography for process-scale antibody purification.

The large-scale production of recombinant monoclonal antibodies demands economical purification processes with high throughputs. The potential for ion-exchange membrane adsorbers to replace traditional ion-exchange columns was evaluated. Breakthrough capacities of commercially available cation-exchange membranes were determined as a function of flow-rate and layer number. Due to economic and process restrictions, cation-exchange membranes may not currently be advantageous for process-scale antibody purification in a bind and elute mode. However, anion-exchange membranes in a flow-through mode may provide a reasonable alternative to columns for the removal of low levels of impurities such as DNA, host cell protein, and virus.

Histocompatibility antigen studies in women with recurrent miscarriages and Müllerian uterine anomalies.

OBJECTIVE: To determine whether the HLA alleles DR1, DR3, DR4 and DR10 which have been suggested to be risk markers for unexplained recurrent miscarriages also play a part in women with recurrent miscarriages with Müllerian uterine fusion anomalies. STUDY DESIGN: HLA-DR typing was undertaken in 28 women with recurrent miscarriage who had been surgically treated for Müllerian anomalies and in 360 controls. In the study group, outcome of pregnancies after surgery was correlated to the results of the HLA typing. RESULTS: In the study group, 61% were positive for HLA-DR1, -DR3, -DR4 or -DR10 compared with 65% of the controls (not significantly different). Among patients positive for these HLA risk markers, 64% of the pregnancies after surgery miscarried compared with 13% in those negative (P<0.005, RR for miscarriage=4.8, 95% CI= 1.3-18.0). CONCLUSION: The proposed risk HLA markers for unexplained recurrent miscarriage also seem to display a negative impact on pregnancy outcome in patients with recurrent miscarriages with Müllerian uterine anomalies.

The use of kriging to estimate monthly ozone exposure parameters for the Southeastern United States.

This paper explores the feasibility of (1) using kriging to predict the monthly mean of daily 7-h mean (0900-1559) O3 concentrations, (2) using kriging to estimate the per cent of hourly mean O3 concentrations equal to or greater than 0.07 ppm (137 microg m(-3)) for a specific month, and (3) developing a quantitative relationship between the monthly mean of the daily 7-h (0900-1559) average O3 concentration and the monthly number of hourly concentrations > or = 0.08p ppm (157 microg m(-3)). We found that kriging can be used to estimate the (1) monthly mean of daily 7-h mean O3 concentrations and (2) the percentage of hourly concentrations for a given month > or = 0.07 ppm when sufficient spatial coverage was available. However, the per cent > or = 0.07 ppm parameter exhibited much greater relative variability than the monthly 7-h exposure index. A strong statistical association was found between the monthly number of occurrences > or = 0.08 ppm and monthly 7-h mean concentrations above 0.05 ppm (98 microg m(-3)). Because of the variability that cumulative indices, such as the monthly percentage of hourly concentrations > or = 0.07 ppm , exhibit from site to site, it appears that whether kriging techniques or mathematical regressions are used to estimate the number of elevated O3 hourly concentrations above selected thresholds, large uncertainties associated with the predicted values will exist. These large uncertainties will make it difficult to accurately estimate vegetation effects caused by ambient levels of O3. However, if a generalized quantitative relationship between repeated occurrences of hourly mean concentrations > or = 0.07 ppm or > or = 0.08 and vegetation effects can be developed, it may be possible, using kriged monthly values accompanied with confidence intervals, to identify those areas where vegetation may be at risk. However, before it will be possible to implement such an approach, researchers will have to better quantify the relationship between realistic O3 exposures and vegetation effects.