All eight Air Quality Management Areas have achieved compliant nitrogen dioxide levels.
The milestone, reached in Wiltshire, marks a significant achievement in the county's efforts to improve public health and environmental standards.
The announcement was made by Wiltshire Council following the presentation of a report to the Environment Select Committee on September 9.
Councillor Paul Sample JP, cabinet member for environment and climate, said: "Air pollution contributes to the equivalent of 30,000 deaths in the UK this year - according to the Royal College of Physicians.
"No-one in Wiltshire wants to live in a County that has high levels of air pollution.
"This work is all about safeguarding and improving the health of residents - and future generations.
"I am delighted that the quality of air in our eight Air Quality Management Areas now meets the targets set.
"It is a big environmental and public health milestone.
"However, the hard work won't stop. Wiltshire Council are committed to gathering evidence to help us maintain and improve air quality."
The council's 2024 Annual Status Report, submitted to Defra in July, confirms that nitrogen dioxide levels have remained below the national objective across all eight AQMAs.
The areas include Bradford on Avon, Marlborough, Calne, Westbury, Devizes, and three locations in Salisbury.
These improvements are the result of long-term actions under the council's Air Quality Action Plan, ongoing monitoring, and community engagement.
Most AQMAs were declared due to long-term breaches of nitrogen dioxide limits, often in areas with high traffic volumes and poor airflow due to narrow road layouts.
The council now plans to consider revoking some of the AQMAs over the next 12 months, in line with Defra guidance.
Revocation requires either three consecutive years of data 10 per cent below the objective, or five years below the threshold.
Councillor Sample said: "Our Air Quality Annual Status Report has been sent to the Government.
"It summarises our efforts to reduce air pollution and improve air quality. It includes the launch of the Wiltshire Community Air Network.
"Our Air Quality Action Plan will make sure we stay on track in making Wiltshire a great place to breath!
"We have also launched an air quality Supplementary Planning Document.
"This is expected to go forward for adoption by the new administration in October."
The council's broader environmental strategy is set out in its Council Plan, which prioritises long-term environmental protection and public health.