Evidence of use of toxic gas chemical weapons in the Syrian war has been reported by governmental and non-governmental international organizations since the war started in March 2011. To date, the profiles of victims of the largest chemical attacks in Syria remain unknown. In this study, we used descriptive epidemiological analysis to describe demographic characteristics of victims of the largest chemical weapons attacks in the Syrian war. We analysed conflict-related, direct deaths from chemical weapons recorded in non-government-controlled areas by the Violation Documentation Center, occurring from March 18, 2011 to April 10, 2017, with complete information on the victim's date and place of death, cause and demographic group. 'Major' chemical weapons events were defined as events causing ten or more direct deaths. As of April 10, 2017, a total of 1206 direct deaths meeting inclusion criteria were recorded in the dataset from all chemical weapons attacks regardless of size. Five major chemical weapons attacks caused 1084 of these documented deaths. Civilians comprised the majority (n = 1058, 97.6%) of direct deaths from major chemical weapons attacks in Syria and combatants comprised a minority of 2.4% (n = 26). In the first three major chemical weapons attacks, which occurred in 2013, children comprised 13%-14% of direct deaths, ranging in numbers from 2 deaths among 14 to 117 deaths among 923. Children comprised higher proportions of direct deaths in later major chemical weapons attacks, forming 21% (n = 7) of 33 deaths in the 2016 major attack and 34.8% (n = 32) of 92 deaths in the 2017 major attack. Our finding of an extreme disparity in direct deaths from major chemical weapons attacks in Syria, with 97.6% of victims being civilians and only 2.4% being combatants provides evidence that major chemical weapons attacks were indiscriminate or targeted civilians directly; both violations of International Humanitarian Law (IHL). Identifying and quantifying chemical weapons violations requires inter-disciplinary collaboration to inform international policy, humanitarian intervention and legal action.

BACKGROUND: Since March, 2011, the Syrian civil war has lowered life expectancy by as much as 20 years. We describe demographic, spatial, and temporal patterns of direct deaths of civilians and opposition combatants from conflict-related violence in 6 years of war. METHODS: We analysed conflict-related violent deaths with complete information on date, place, and cause of death and demographic group occurring from March 18, 2011, to Dec 31, 2016, recorded by the Violation Documentation Center (VDC). We included civilian and combatant deaths in all Syrian governorates, excluding government-controlled areas. We did not include detainees and missing persons, nor deaths from siege conditions or insufficient medical care. We categorised deaths based on VDC weapon type. We used chi(2) testing to compare deaths from different weapons in civilian men, women, boys, and girls and adult and child combatants. We analysed deaths by governorate and over time. FINDINGS: The VDC recorded 143 630 conflict-related violent deaths with complete information between March 18, 2011, and Dec 31, 2016. Syrian civilians constituted 101 453 (70.6%) of the deaths compared with 42 177 (29.4%) opposition combatants. Direct deaths were caused by wide-area weapons of shelling and air bombardments in 58 099 (57.3%) civilians, including 8285 (74.6%) civilian women and 13 810 (79.4%) civilian children, and in 4058 (9.6%) opposition combatants. Proportions of children among civilian deaths increased from 8.9% (388 of 4254 civilian deaths) in 2011 to 19.0% (4927 of 25 972) in 2013 and to 23.3% (2662 of 11 444) in 2016. Of 7566 deaths from barrel bombs, 7351 (97.2%) were civilians, of whom 2007 (27.3%) were children. Of 20 281 deaths by execution, 18 747 (92.4%) were civilians and 1534 (7.6%) were opposition combatants. Compared with opposition child soldiers who were male (n=333), deaths of civilian male children (n=11 730) were caused more often by air bombardments (39.2% vs 5.4%, p < 0.0001) and shelling (37.3% vs 13.2%, p < 0.0001) and less often by shooting (12.5% vs 76.0%, p < 0.0001). INTERPRETATION: Aerial bombing and shelling rapidly became primary causes of direct deaths of women and children and had disproportionate lethal effects on civilians, calling into question the use of wide-area explosive weapons in urban areas. Increased reliance on aerial bombing by the Syrian Government and international partners is likely to have contributed to findings that children were killed in increasing proportions over time, ultimately comprising a quarter of civilian deaths in 2016. The inordinate proportion of civilians among the executed is consistent with deliberate tactics to terrorise civilians. Deaths from barrel bombs were overwhelmingly civilian rather than opposition combatants, suggesting indiscriminate or targeted warfare contrary to international humanitarian law and possibly constituting a war crime. FUNDING: None.

Article introduction: What started as a peaceful uprising in Syria in March 2011 escalated quickly to an armed conflict. By 2012 conflict had become the leading cause of death of Syrians. Health systems have been reshaped, now being separated into areas controlled by the government, the opposition, or self proclaimed Islamic State factions—we group the last two as non-state armed groups (NSAG; fig 1). These areas differ vastly in terms of service delivery capacity, number of trained staff, and accessto essential medicines. Indirect conflict related deaths have arisen from poor sanitation and severe disruption to Syria’s healthcare system. In December 2014, 20% of Syria’s public hospitals were completely non-functional, and another 35% provided only partial services. Direct conflict related deaths are those that are caused by weapons and other violent methods used in warfare. In this article we assess the direct conflict related deaths (hereafter termed violent deaths) of women and children among civilians killed in the Syrian conflict, because they are identified as vulnerable populations in public health and under specific laws of war such as the Geneva Conventions.