Currently, marine algae are capturing the attention of both farmers and researchers eager to integrate sustainable methods to safeguard their crops. Instead of relying exclusively on synthetic pesticides, which often have negative environmental effects, some growers are now exploring algae-based products in hopes of reducing pest pressures. Various natural compounds sourced from algae—such as specific fatty acids and complex sugars—are believed to inhibit pest development, although their precise mechanisms are yet to be fully understood. Furthermore, there is some evidence suggesting that these compounds may bolster the plant’s own immune responses, thus enhancing crop resilience. Despite certain limitations on field applications, various techniques, including spraying, amending soil, or pre-treating seeds, are currently being evaluated. The results from the laboratory present a positive outlook, but implementing these discoveries to ensure consistent efficacy in practical settings is a major challenge. Variables such as climatic fluctuations, product durability, and formulation standards all elevate this complexity. In every instance, the approach of incorporating algae to lessen chemical dependence while securing uniform yields persists in being of interest, particularly in the area of organic or low-input farming.

After the outbreak of COVID-19 pandemic in Bulgaria, the government has declared “state of emergency” (from March 13th, 2020) and took instant and decisive measures, including suspension of all educational activities, ban on access to all public places, installation of checkpoints on entrance-exit roads of the regional centers, to prevent the spread of the infection. The aim of this article is to evaluate the effectiveness of the “state of emergency” on the air quality improvement. In particular, an interrupted time series modelling approach is employed to test if a significant change in the level and the trend of the pollutant time series has occurred after the “state of emergency” measure. The case study regards the city of Stara Zagora, Bulgaria and focuses on the comparison of the period before (January 1st – March 12th, 2020) and after (March 13th – December 15th, 2020) the state of emergency. After adjusting by meteorology and Sunday effect, the results confirm for negative and significant effect in the level for NO₂ and SO₂ immediately after the state of emergency and positive and significant trend only for NO₂. For the remaining PM₁₀ series of data, it is not possible to conclude that the intervention was helpful in improving air quality. These results are reasonable due to the stay-at-home order has certainly lowered road traffic on the one hand, thus reducing the main emission source connected to NO₂ concentrations and on the other hand increase PM₁₀ concentrations because in Stara Zagora city, solid fuel heating is the main source for PM.