In our complex, changing world, some environmental health problems are not straightforward to identify until a very serious health impact occurs. When health problems do emerge, we may only have a very short period of time and opportunity in which to react, identify and restore the damaged natural environment. As a result, we strongly assert the necessity to understand the environment and its relationship with pathogens in air before health hazards associated with the relevant pathogens can appear. In the present paper we have briefly reviewed and presented our views on various issues. Our next step is to encourage and support focused multidisciplinary research in order to fill the missing knowledge gaps and translate research into practice and policy. Combination strategies for pandemic influenza response - a systematic review of mathematical modeling studies BACKGROUND: Individual strategies in pandemic preparedness plans may not reduce the impact of an influenza pandemic. METHODS: We searched modeling publications through PubMed and associated references from 1990 to 30 September 2009. Inclusion criteria were modeling papers quantifying the effectiveness of combination strategies, both pharmaceutical and non-pharmaceutical. RESULTS: Nineteen modeling papers on combination strategies were selected. Four studies examined combination strategies on a global scale, 14 on single countries, and one on a small community. Stochastic individual-based modeling was used in nine studies, stochastic meta-population modeling in five, and deterministic compartmental modeling in another five. As part of combination strategies, vaccination was explored in eight studies, antiviral prophylaxis and/or treatment in 16, area or household quarantine in eight, case isolation in six, social distancing measures in 10 and air travel restriction in six studies. Two studies suggested a high probability of successful influenza epicenter containment with combination strategies under favorable conditions. During a pandemic, combination strategies delayed spread, reduced overall number of cases, and delayed and reduced peak attack rate more than individual strategies. Combination strategies remained effective at high reproductive numbers compared with single strategy. Global cooperative strategies, including redistribution of antiviral drugs, were effective in reducing the global impact and attack rates of pandemic influenza. CONCLUSION: Combination strategies increase the effectiveness of individual strategies. They include pharmaceutical (antiviral agents, antibiotics and vaccines) and non-pharmaceutical interventions (case isolation, quarantine, personal hygiene measures, social distancing and travel restriction). Local epidemiological and modeling studies are needed to validate efficacy and feasibility. Many countries have developed pandemic preparedness plans in response to the threat from pandemic influenza [1] , to attempt containment of the virus or to reduce the pandemic's impact. The influenza A (H1N1-2009) pandemic has underscored the importance of such plans, with the World Health Organization (WHO) calling for the activation of pandemic plans worldwide [2] . Although the WHO has made public guidelines for developing pandemic plans [3] , the comprehensiveness and standards of pandemic plans differ widely across different countries and continents [4] [5] [6] . To ensure the success of these plans, it is necessary to adopt a combination of different strategies.