Which of the following statements is true regarding soil fumigants and air quality?

The statement that all soil fumigants contribute to smog formation is accurate. This is because many soil fumigants release volatile organic compounds (VOCs) into the atmosphere during application and through soil volatilization. VOCs can react with nitrogen oxides in the presence of sunlight to form ground-level ozone, a key component of smog. This is an important consideration for environmental health, as smog can lead to respiratory problems and other health issues in the population.

Regarding the other options, it is not true that only methyl bromide affects air quality. Numerous soil fumigants can have an impact on air quality due to their chemical properties. Additionally, not all soil fumigants are considered safe for air quality; many have been shown to have harmful environmental effects. Lastly, air quality can be affected by fumigants in various forms, not just liquid, meaning that the claim about only liquid fumigants affecting air quality does not hold true. Therefore, the first statement accurately reflects the broader environmental impact of soil fumigants.