Respiratory effects of non-tobacco cigarettes.

Data from the Tucson epidemiological study of airways obstructive disease on smoking of non-tobacco cigarettes such as marijuana were analysed to determine the effect of such smoking on respiratory symptoms and pulmonary function. Among adults aged under 40, 14% had smoked non-tobacco cigarettes at some time and 9% were current users. The prevalence of respiratory symptoms was increased in smokers of non-tobacco cigarettes. After tobacco smoking had been controlled for men who smoked non-tobacco cigarettes showed significant decreases in expiratory flow rates at low lung volumes and in the ratio of the forced expiratory volume in one second to the vital capacity. This effect on pulmonary function in male non-tobacco cigarette smokers was greater than the effect of tobacco cigarette smoking. These data suggest that non-tobacco cigarette smoking may be an important risk factor in young adults with respiratory symptoms or evidence of airways obstruction.     

Effect of inhaled corticosteroids on episodes of wheezing associated with viral infection in school age children: randomised double blind placebo controlled trial.

OBJECTIVES: To determine the effect of regular prophylactic inhaled corticosteroids on wheezing episodes associated with viral infection in school age children. DESIGN: Randomised, double blind, placebo controlled trial. SETTING: Community based study in Southampton. SUBJECTS: 104 children aged 7 to 9 years who had had wheezing in association with symptoms of upper and lower respiratory tract infection in the preceding 12 months. INTERVENTIONS: After a run in period of 2-6 weeks children were randomly allocated twice daily inhaled beclomethasone dipropionate 200 micrograms or placebo through a Diskhaler for 6 months with a wash out period of 2 months. Children were assessed monthly. MAIN OUTCOME MEASURES: Forced expiratory volume in 1 second (FEV1); bronchial responsiveness to methacholine (PD20); percentage of days with symptoms of upper and lower respiratory tract infection with frequency, severity, and duration of episodes of upper and lower respiratory symptoms and of reduced peak expiratory flow rate. RESULTS: During the treatment period there was a significant increase in mean FEV1 (1.63 v 1.53 1; adjusted difference 0.09 1 (95% confidence interval 0.04 to 0.14); P = 0.001) and methacholine PD20 12.8 v 7.2 mumol/l; adjusted ratio of means 1.7 (1.2 to 2.4); P = 0.007) in children receiving beclomethasone dipropionate compared with placebo. There were, however, no significant differences in the percentage of days with symptoms or in the frequency, severity, or duration of episodes of upper or lower respiratory symptoms or of reduced peak expiratory flow rate during the treatment period between the two groups. CONCLUSIONS: Although lung function is improved with regular beclomethasone dipropionate 400 micrograms/day, this treatment offers no clinically significant benefit in school age children with wheezing episodes associated with viral infection.     

Impact of a waste disposal site on adult respiratory health

Introduction. This study evaluated the impact of the presence of a dump on respiratory health in adults older than 50 years of age, living in its area of influence. Materials and methods. A cohort study was conducted with 313 adults older than 50 years of age living near the Navarro Dump (Cali, Colombia) and compared with 359 adults in an unexposed area. Each was examined monthly during a 6 month period to compare the incidence of respiratory symptoms and alterations in peak expiratory flow. Results. Exposure to the Navarro Dump was associated with occurrence of respiratory symptoms (odds ratio=1.25, 95% C.I. 1.01-1.56), in particular with mild respiratory symptoms (odds ratio=1.28, 95% C.I. 0.98-1.66). This result was obtained after adjusting for age, sex, education level, humidity, health insurance, comorbidity, smoking and previous occupational exposure. A higher recurrence of symptoms was found in adults in the area of exposure (correlation coefficient=0.29, 95% C.I. 0.23-0.33, p<0.001) and a significant reduction in the lung function defined by peak expiratory flow; the average decrease was15.2 L/min (95% C.I. -30.2 to +0.22). Conclusion. Independent of potential confounding factors, the respiratory health of adults exposed to the Navarro Dump was affected and exhibited an increased occurrence and recurrence of mild respiratory symptoms as well as decreased lung function.     

Long-term air pollution exposure and living close to busy roads are associated with COPD in women

Background

Lung function and exacerbations of chronic obstructive pulmonary disease (COPD) have been associated with short-term exposure to air pollution. However, the effect of long-term exposure to particulate matter from industry and traffic on COPD as defined by lung function has not been evaluated so far. Our study was designed to investigate the influence of long-term exposure to air pollution on respiratory symptoms and pulmonary function in 55-year-old women. We especially focused on COPD as defined by GOLD criteria and additionally compared the effects of air pollution on respiratory symptoms by questionnaire data and by lung function measurements.

Methods

In consecutive cross sectional studies conducted between 1985–1994, we investigated 4757 women living in the Rhine-Ruhr Basin of Germany. NO₂ and PM₁₀ exposure was assessed by measurements done in an 8 km grid, and traffic exposure by distance from the residential address to the nearest major road using Geographic Information System data. Lung function was determined and COPD was defined by using the GOLD criteria. Chronic respiratory symptoms and possible confounders were defined by questionnaire data. Linear and logistic regressions, including random effects were used to account for confounding and clustering on city level.

Results

The prevalence of COPD (GOLD stages 1–4) was 4.5%. COPD and pulmonary function were strongest affected by PM₁₀ and traffic related exposure. A 7 μg/m₃ increase in five year means of PM₁₀ (interquartile range) was associated with a 5.1% (95% CI 2.5%–7.7%) decrease in FEV₁, a 3.7% (95% CI 1.8%–5.5%) decrease in FVC and an odds ratio (OR) of 1.33 (95% CI 1.03–1.72) for COPD. Women living less than 100 m from a busy road also had a significantly decreased lung function and COPD was 1.79 times more likely (95% CI 1.06–3.02) than for those living farther away. Chronic symptoms as based on questionnaire information showed effects in the same direction, but less pronounced.

Conclusion

Chronic exposure to PM₁₀, NO₂ and living near a major road might increase the risk of developing COPD and can have a detrimental effect on lung function.     

Effects of prematurity and intrauterine growth on respiratory health and lung function in childhood.

OBJECTIVE--To determine whether birth weight and gestational age are associated with respiratory illness and lung function in children aged 5-11 years. DESIGN--Cross sectional analysis of parent reported birth weight, gestational age, and respiratory symptoms; parental smoking and social conditions; forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory rates between 25% and 75% and 75% and 85% (FEF25-75 and FEF75-85), and height. SETTING--Primary schools in England and Scotland in 1990. SUBJECTS--5573 children aged 5-11 (63.3% of eligible children) had respiratory symptoms analysed and 2036 children (67.1% of eligible children) had lung function measured. MAIN OUTCOME MEASURES--Symptoms of asthma, bronchitis, occasional and frequent wheeze, cough first thing in the morning, and cough at any other time and lung function. RESULTS--Birth weight adjusted for gestational age was significantly associated with all lung function measurements, except FEF25-75. The association remained for FVC (b = 0.475, 95% confidence interval 0.181 to 0.769) and FEV1 (b = 0.502, 0.204 to 0.800) after adjustment for gestational age, parental smoking, and social factors. FEF75-85 was the only lung function related to gestational age. Respiratory symptoms, especially wheeze most days (adjusted odds ratio 0.9, 0.84 to 0.97) were significantly associated with prematurity. Every extra week of gestation reduced the risk of severe wheeze by about 10%. CONCLUSIONS--Lung function is affected mainly by intrauterine environment while respiratory illness, especially wheezing, in childhood is related to prematurity.     

Community study of role of viral infections in exacerbations of asthma in 9-11 year old children.

OBJECTIVE--To study the association between upper and lower respiratory viral infections and acute exacerbations of asthma in schoolchildren in the community. DESIGN--Community based 13 month longitudinal study using diary card respiratory symptom and peak expiratory flow monitoring to allow early sampling for viruses. SUBJECTS--108 Children aged 9-11 years who had reported wheeze or cough, or both, in a questionnaire. SETTING--Southampton and surrounding community. MAIN OUTCOME MEASURES--Upper and lower respiratory viral infections detected by polymerase chain reaction or conventional methods, reported exacerbations of asthma, computer identified episodes of respiratory tract symptoms or peak flow reductions. RESULTS--Viruses were detected in 80% of reported episodes of reduced peak expiratory flow, 80% of reported episodes of wheeze, and in 85% of reported episodes of upper respiratory symptoms, cough, wheeze, and a fall in peak expiratory flow. The median duration of reported falls in peak expiratory flow was 14 days, and the median maximum fall in peak expiratory flow was 81 l/min. The most commonly identified virus type was rhinovirus. CONCLUSIONS--This study supports the hypothesis that upper respiratory viral infections are associated with 80-85% of asthma exacerbations in school age children.     

Damp housing and childhood asthma: validation of reporting of symptoms.

The relations among parental reports of respiratory symptoms, bronchospasm measured after exercise, and the presence of visible fungal mould in the home was assessed in a population sample of 7 year old children (n = 873). Wheeze in the past year was the symptom most closely associated with reported dampness and particularly with mould. The unadjusted odds ratio relating mould and wheeze was 3.70 (95% confidence interval 2.22 to 6.15), and after adjustment for housing tenure, number of people per room, number of smokers in the household, and gas cooking this remained highly significant (odds ratio 3.00 (1.72 to 5.25)). The reduction in forced expiratory volume in one second after six minutes of free running was used to validate reporting of wheeze. At all levels of measured bronchial lability wheeze was reported more commonly in the children from homes with mould. There was no significant difference in the degree of bronchospasm measured among children from homes with and without mould. Awareness of dampness or mould in the home may be a determinant of parental reporting of symptoms and may account for much of the observed association between mould and respiratory symptoms.     

Fatal Car Occupant Injuries after Car Lorry Collisions

All deaths from road accidents in certain areas and periods were studied. Analysis of 224 deaths to car occupants from collisions between cars and lorries showed that such accidents were the commonest cause of death for car occupants on motorways and link roads. The impacts were such that relatively poor protection could be given by occupant restraint systems. Collisions of cars into the rear of lorries caused the most severe injuries; most of these accidents occurred at night.The traffic characteristics of cars and lorries are largely incompatible and increase the likelihood of collisions and of extremely severe injuries to car occupants. Some reduction in deaths may be expected from making lorries more conspicuous and eliminating the rear overhang. More fundamental measures are segregation of lorries from cars and return of traffic to railways.     

Systemic and discoid lupus erythematosus: analysis of pulmonary function

To determine the prevalence of pulmonary dysfunction in lupus erythematosus, 24 patients with systemic lupus erythematosus (SLE) and 5 patients with discoid lupus erythematosus (DLE) were studied. Diffusing capacity for carbon monoxide was abnormal in 17 (71 percent) SLE patients. A restrictive ventilatory defect was present in 6 (25 percent) and arterial hypoxemia in 4 of 23 (17 percent). The mean ratio of forced expiratory volume in one second to forced vital capacity (FVC) was 83 percent. To test for the presence of small airways disease, maximum expiratory flow rate at 50 percent of FVC was measured on air and on an 80 percent helium-20 percent oxygen mixture. Ten patients (5 smokers and 5 nonsmokers) with SLE were nonresponders to helium suggesting small airways disease. Pulmonary dysfunction was present in 90 percent (9/10) of SLE patients with a previous history of pleuritis and/or pneumonitis, and in 71 percent (10/14) without respiratory symptoms or history of lung disease and with a normal chest radiograph. Pulmonary function tests were normal in DLE patients except for an abnormal response to helium and/or mild arterial hypoxemia in two patients, all of whom were smokers. These data indicate that there is a high prevalence of pulmonary function abnormalities in SLE including patients without clinically evident pleuropulmonary disease.     

Epidemiological study of wheeze,doctor diagnosed asthma,and cough in preschool children in Leicestershire.

OBJECTIVE--To determine the cumulative prevalences of wheeze and doctor diagnosed asthma and the point prevalences of recurrent cough and wheeze in children aged 5 years and under. DESIGN--Questionnaire survey of population based random sample of children registered on regional authority''s child health index for immunisation; questionnaire completed by parents. SETTING--Leicestershire. SUBJECTS--1650 white children born in 1985-9 who were surveyed in 1990. MAIN OUTCOME MEASURES--Cumulative prevalences of wheeze and doctor diagnosed asthma and point prevalences of recurrent cough and wheeze by age and sex. RESULTS--There were 1422 replies (86.2%; 726 for boys, 696 for girls). Overall, 11.0% (95% confidence interval 9.4% to 12.6%) of children had formally been diagnosed as having asthma, the cumulative prevalence in boys (12.7%) being somewhat higher than in girls (9.2%) (age adjusted odds ratio 1.47, p = 0.03). As expected, the cumulative prevalence of asthma increased significantly with age (7.5% (13/173) in children under 1 year, 15.9% (61/383) in children of 4 years and over; p < 0.001). The cumulative prevalence of wheeze overall was 15.6% (13.7% to 17.5%), being higher in boys (17.6%) than in girls (13.5%) (odds ratio 1.38, p = 0.03). The overall prevalence of recurrent cough without colds was 21.8% (19.6% to 23.9%), with a non-significant excess in boys (23.1% v 20.4%). The overall prevalence of wheezing attacks during the previous 12 months was 13.0% (11.3% to 14.8%) with a non-significant excess in boys (14.5% v 11.5%). CONCLUSIONS--These findings are baseline results and emphasise the importance of studying the age group of interest rather than relying on the recall of parents of school age children.     

Respiratory Health before and after the Opening of a Road Traffic Tunnel: A Planned Evaluation

Objective

The construction of a new road tunnel in Sydney, Australia, and concomitant reduction in traffic on a major road presented the opportunity to study the effects of this traffic intervention on respiratory health.

Methods

We made measurements in a cohort of residents in the year before the tunnel opened (2006) and in each of two years afterwards (2007–2008). Cohort members resided in one of four exposure zones, including a control zone. Each year, a respiratory questionnaire was administered (n = 2,978) and a panel sub-cohort (n = 380) performed spirometry once and recorded peak expiratory flow and symptoms twice daily for nine weeks.

Results

There was no consistent evidence of improvement in respiratory health in residents living along the bypassed main road, despite a reduction in traffic from 90,000 to 45,000 vpd. Residents living near tunnel feeder roads reported more upper respiratory symptoms in the survey but not in the panel sub-cohort. Residents living around the tunnel ventilation stack reported more upper and lower respiratory symptoms and had lower spirometric volumes after the tunnel opened. Air pollutant levels measured near the stack did not increase over the study period.

Conclusion

The finding of adverse health effects among residents living around the stack is unexpected and difficult to explain, but might be due to unmeasured pollutants or risk factors or an unrecognized pollutant source nearby. The lack of improvement in respiratory health among people living along the bypassed main road probably reflects a minimal change in exposure due to distance of residence from the road.     

Cooperation and Defection at the Crossroads

We study a simple traffic model with a non-signalized road intersection. In this model the car arriving from the right has precedence. The vehicle dynamics far from the crossing are governed by the rules introduced by Nagel and Paczuski, which define how drivers behave when braking or accelerating. We measure the average velocity of the ensemble of cars and its flow as a function of the density of cars on the roadway. An additional set of rules is defined to describe the dynamics at the intersection assuming a fraction of drivers that do not obey the rule of precedence. This problem is treated within a game-theory framework, where the drivers that obey the rule are cooperators and those who ignore it are defectors. We study the consequences of these behaviors as a function of the fraction of cooperators and defectors. The results show that cooperation is the best strategy because it maximizes the flow of vehicles and minimizes the number of accidents. A rather paradoxical effect is observed: for any percentage of defectors the number of accidents is larger when the density of cars is low because of the higher average velocity.     

Prevalence of tidal expiratory flow limitation in preschool children with and without respiratory symptoms: application of the negative expiratory pressure (NEP) method

Negative expiratory pressure (NEP) applied at the mouth during tidal expiration provides a non-invasive method for detecting expiratory flow limitation. Forty-two children were studied, i.e. 25 children with different respiratory symptoms (R) and 17 without any respiratory symptoms (NR). Children were examined without any sedation. A preset NEP of -5 cm H(2)O was applied; its duration did not exceed duration of tidal expiration. A significance of FL was judged by determining of a flow-limited range (in % of tidal volume). FL was found in 48 % children of R group. No patient of the NR group elicited FL (P<0.001 R vs. NR). The frequency of upper airway collapses was higher in R group (12 children) than in NR group (5 children). In conclusion, a high frequency of tidal FL in the R group was found, while it was not present in NR group. A relatively high frequency of expiratory upper airway collapses was found in both groups, but it did not differ significantly. NEP method represents a reasonable approach for tidal flow limitation testing in non-sedated preschool children.     

Are seat belt restraints as effective in school age children as in adults? A prospective crash study

ObjectiveTo study effectiveness of seat belts for protecting school age children in road vehicle crashes.DesignCrash examinations by trained investigators.SettingTen Canadian university based crash investigation centres.Subjects470 children aged 4-14 years, with 168 selected for detailed analysis, and 1301 adults.ResultsOverall, 40% (189/470) of children were unbelted. Of the 335 children in cars driven by belted adults, 73 (22%) were unbelted. The odds of sustaining fatal or moderately severe injury (injury severity score ⩾4) for children in the front passenger seat was more than nine times higher for unbelted children than for belted ones (odds ratio 9.8 (95% confidence interval 2.4 to 39.4)) and for those in the rear left seat was more than two times higher for unbelted than for belted children (2.6 (1.1 to 5.9)). The protection afforded by seat belts compared favourably with the results for adults in the same seat positions (odds ratios for unbelted v belted adults of 2.4 and 2.7 for front and rear seat passengers respectively).ConclusionsSeat belts helped to protect school age children from injury in road vehicle crashes. However, 40% of children were unbelted. Despite standard seat belts being designed for adults, school age children were at least as well protected as adults.

What is already known on this topic

Although child restraints protect young children in road vehicle crashes, it is not known whether standard seat belts used by school age children work as wellSchool age children are often unbelted in cars

What this study adds

Data from detailed crash assessments indicate that seat belts protected children at least as well as adultsAdults were more likely than children to be belted, and 22% of children travelling with belted drivers were unbelted     

Injuries to pedestrians in road traffic accidents.

Although there have been many reports on injuries to occupants of cars in road traffic accidents, there have been few prospective studies of injuries to pedestrians in such accidents. For this reason a two year prospective study of pedestrians in road traffic accidents in the Oxford region was carried out. The incidence of death in pedestrians was significantly higher than in car occupants or motorcyclists. The principal determinant of death was the weight of the vehicle concerned. The most common site of injury was the head because of a high incidence of brief concussion, but the most common site of serious injuries was the leg. Injuries to all regions of the body increased with age and with the weight of the vehicle in the collision. Accidents most often concerned young children or the elderly.     

Association of common health symptoms with bullying in primary school children.

OBJECTIVE--To estimate the prevalence of bullying in primary school children and to examine its association with common symptoms in childhood. DESIGN--Semistructured health interview conducted by school nurses as part of a school medical. SETTING--Newham, east London. SUBJECTS--All children in year 4 of school during the academic year 1992-93. MAIN OUTCOME MEASURES--Reported bullying and common health symptoms. RESULTS--2962 children (93.1% of those on the school roll) were interviewed (ages 7.6 to 10.0 years). Information about bullying was not recorded for 114 children, 22.4% (95% confidence interval 20.9 to 24.0) of children for whom information was available reported that they had been bullied. There was an association between children reporting being bullied sometimes or more often and reporting not sleeping well (odds ratio 3.6, 2.5 to 5.2), bed wetting (1.7, 1.3 to 2.4), feeling sad (3.6, 1.9 to 6.8), and experiencing more than occasional headaches (2.4, 1.8 to 3.4) and tummy aches (2.4, 1.8 to 3.3). A significant trend for increasing risk of symptoms with increased frequency of bullying was shown for all reported health symptoms (P < 0.001). CONCLUSIONS--Health professionals seeing primary schoolchildren who present with headaches, tummy ache, feeling sad or very sad, bed wetting, and sleeping difficulties should consider bullying as a possible contributory factor.     

Factors Influencing the Onset of Chronic Respiratory Disease

To investigate the effect of different environmental and personal factors on ventilatory function 10,971 children resident and going to school in four areas of Kent were examined. Details of past respiratory illnesses were obtained by a questionary completed by the parents; the examination included measurement of height, weight, and peak expiratory flow.Area of residence, social class, family size, and a past history of pneumonia, bronchitis, or asthma were found to be associated with differing levels of peak expiratory flow. These four factors acted independently, and the effects were additive. It is suggested that environment in the early years of life can produce adverse changes which may exist throughout life and contribute to the development of chronic respiratory disease.     

Effects of reduction mammaplasty on pulmonary function and symptoms of macromastia

A number of studies have documented subjective improvement in somatic and psychological symptoms following breast reduction surgery. Objective data demonstrating improved postoperative function have been more difficult to assess, and particularly with respect to pulmonary function, the results have been contradictory. In this prospective study, patients completed a comprehensive preoperative questionnaire modified from the American Thoracic Society Division of Lung Diseases Epidemiology Standardization Project (1978). This questionnaire noted subjective pulmonary symptoms and pulmonary medical history. In addition, subjective symptoms related to breast size, including back and neck pain and shoulder pain and grooving, and a subjective evaluation of body image, were evaluated. All subjects received preoperative pulmonary function testing, including spirometry, lung volume measurements, and measurement of peak inspiratory and expiratory flow rates and pressures. Eight weeks after breast reduction, a repeat questionnaire and pulmonary function testing were administered. Preoperative and postoperative pulmonary function values were compared using Cochran-Mantel-Haenszel tests, and correlations were tested between changes in pulmonary function test values and subjective symptom improvement. Forty-four patients underwent an average of 2228-g bilateral reduction. All of these patients had their surgical procedures preauthorized as medically necessary by their insurance carriers. All subjective parameters examined were statistically significantly improved following breast reduction (p < 0.001). Of the 17 patients with preoperative complaints of shortness of breath, all noted significant improvement following breast reduction surgery (p < 0.001). Of the objective pulmonary criteria evaluated, inspiratory capacity, peak expiratory flow rate, and maximal voluntary ventilation showed a statistically significant improvement following surgery (p < 0.05). These changes correlated with body mass index; the greater the index, the greater the change in maximal voluntary ventilation and peak expiratory flow rate. Smokers in this group had the largest change in maximal voluntary ventilation (p < 0.008). No correlation could be found between preoperative pulmonary symptoms, a single subjective symptom, or grams of breast weight reduction and changes in pulmonary function tests. The results show that pulmonary parameters, related primarily to work of breathing (inspiratory capacity, maximal voluntary ventilation, peak expiratory flow rate), were statistically improved following breast reduction surgery, and these changes correlated with body mass index.     

Stimulation of vagal C-fibers alters timing and distribution of respiratory motor output in cats

Pulmonary vascular congestion or pulmonary embolism in humans produces shallow tachypnea, and indirect experimental evidence suggests that this characteristic breathing pattern may result from activation of vagal unmyelinated afferents from the lung. We have investigated, in decerebrate cats, reflex changes in breathing pattern and in the activation of the diaphragm, posterior cricoarytenoid, and thyroarytenoid muscles caused by activating C-fiber afferents in the vagus nerve. The right vagus nerve was sectioned distal to the origin of the recurrent laryngeal nerve, eliminating vagal afferent traffic although preserving motor innervation of the larynx on that side. The left cervical vagus was stimulated electrically, and efferent activation of the laryngeal muscles was avoided by cutting the left recurrent laryngeal nerve. Transmission to the brain of vagal afferent traffic resulting from this stimulation was controlled by graded cold block of the nerve cranial to the site of application of the stimulus. Activation of C-fibers, when A-fibers were blocked, significantly decreased respiratory period and amplitude of diaphragm inspiratory burst. In addition, this selective activation of vagal C-fibers augmented postinspiratory activity of the diaphragm and recruited phasic expiratory bursts in the thyroarytenoid. We conclude that, in unanesthetized decerebrate cats, afferent traffic of vagal C-fibers initiates a pontomedullary reflex that increases respiratory frequency, decreases tidal volume, and augments braking of expiratory airflow.     

The Impact of the Thai Motorcycle Transition on Road Traffic Injury: Thai Cohort Study Results

Objectives

The aim of this study was to investigate the impact of motorcycle to car transitioning and urbanisation on traffic injury rates in Thailand.

Design

Analysis of two consecutive surveys of a large national cohort study.

Setting

Thailand.

Participants

The data derived from 57,154 Thai Cohort Study (TCS) participants who provided relevant data on both the 2005 and 2009 surveys.

Primary and secondary outcome measures

Motorcycle and car traffic crash injury self-reported in 2009, with twelve months’ recall.

Results

In 2009, 5608(10%) participants reported a traffic crash injury. Most crashes involved a motorcycle (74%). Car access increased and motorcycle use decreased between 2005 and 2009. Among those who used a motorcycle at both time points, traffic injury incidence was 2.8 times greater compared to those who did not use a motorcycle at either time point. Multivariable logistic regression models were used to test longitudinal and cross sectional factors associated with traffic crash injury: in the adjusted model, cars were negatively and motorcycles positively associated with injury. Living in an urban area was not injury protective in the adjusted model of traffic crash injury.

Conclusions

Ongoing urbanisation in Thailand can be expected to lead to further reductions in road traffic injuries based on transition from motorcycles to cars in urban areas. Cities, however, do not provide an intrinsically safer traffic environment. To accommodate a safe transition to car use in Thailand, traffic infrastructural changes anticipating the growing car density in urban areas is warranted.