Her research includes the impact of acid rain, nuclear accidents and fine particulates on human health and ecosystems.
[4][5] In the immediate aftermath, Russia issued a media blackout and ApSimon was one of few European scientists to detect rising radiation levels.
[9] ApSimon has also worked extensively for Task Forces under the UN ECE Convention on Long-Range Transboundary Air Pollution, undertaking modelling and assessment of cost-effective strategies to reduce acidification, eutrophication, excess tropospheric ozone and fine particulate concentrations.
[13] In 1998, the UK Department of Environment, Transport and the Regions commissioned ApSimon to study investigate the cost-effectiveness of controlling the shipping emissions in the North Sea.
[18] In the 2013 Queen's Birthday Honours, Helen ApSimon was appointed a Commander of the Order of the British Empire (CBE) for services to air pollution science.