High exposure to NO2 in the week before the start of a respiratory viral infection, and at levels within current air quality standards, is associated with an increase in the severity of a resulting asthma exacerbation.

Shoulder pain is very common and causes substantial morbidity. Standardised classification systems based upon presumed patho-anatomical origins have proved poorly reproducible and hampered epidemiological research. Despite this, there is evidence that exposure to combinations of physical workplace strains such as overhead working, heavy lifting and forceful work as well as working in an awkward posture increase the risk of shoulder disorders. Psychosocial risk factors are also associated. There is currently little evidence to suggest that either primary prevention or treatment strategies in the workplace are very effective and more research is required, particularly around the cost-effectiveness of different strategies. KeywordsShoulder pain; impingement syndrome; frozen shoulder (adhesive capsulitis); rotator cuff Introduction and ScopeAccording to population surveys, shoulder pain affects 18-26% of adults at any point in time [1][2][3][4], making it one of the most common regional pain syndromes. Symptoms can be persistent and disabling in terms of an individual's ability to carry out daily activities both at home and in the workplace [5,6]. There are also substantial economic costs involved, with increased demands on health care, impaired work performance, substantial sickness absence, and early retirement or job loss [7][8][9][10].The shoulder has evolved to withstand heavy physical demands and to do so over an unusually wide range of motion. To achieve this, it is not a simple 'ball and socket' joint but rather a complex composed of four articulations and a supporting arrangement of bones, muscles and ligaments within and outside of the joint capsule. However, its complexity and the nature of the demands on it make it susceptible to a range of articular and peri-articular

Objectives We assessed the evidence relating pre-term delivery (PTD), low birthweight, small for gestational age (SGA), pre-eclampsia and gestational hypertension to five occupational exposures (working hours, shift work, lifting, standing and physical workload). We conducted a systematic search in MEDLINE and EMBASE (1966–2011), updating a previous search with a further six years of observations. Methods As before, combinations of keywords and MeSH terms were used. Each relevant paper was assessed for completeness of reporting and potential for important bias or confounding, and its effect estimates abstracted. Where similar definitions of exposure and outcome existed we calculated pooled estimates of relative risk in meta-analysis. Results Analysis was based on 86 reports (32 cohort investigations, 57 with usable data on PTD, 54 on birthweight and 11 on pre-eclampsia/gestational hypertension); 33 reports were new to this review. For PTD, findings across a substantial evidence base were generally consistent, effectively ruling out large effects (e.g. RR>1.2). Larger and higher quality studies were less positive, while meta-estimates of risk were smaller than previously and best estimates pointed to modest or null effects (RR 1.04 to 1.18). For SGA, the position was similar but meta-estimates were even closer to the null (eight of nine RRs ≤ 1.07). For pre-eclampsia/gestational hypertension the evidence base remains insufficient. Conclusions The balance of evidence is against large effects for the associations investigated. As the evidence base has grown, estimates of risk in relation to these outcomes have become smaller.