Restrictions

Reducing Ozone, PM10, and PM2.5

Please refer to the information below to find out what restrictions, if any, are prohibited based on the current air quality status. “High Pollution Advisory” (HPA), means the highest concentration of pollution may exceed the federal health standard. Active children, adults, and people with lung disease such as asthma should reduce prolonged or heavy outdoor exertion. Maricopa County employers participating in the Travel Reduction Program are asked to activate their HPA plans on high pollution advisory days.

Please note: Certain outdoor fires are prohibited in parts of Maricopa County from May 1 through September 30, including fires used to clear land, branding of animals and fires for recreational use. Other types of fires are allowed unless a restricted burn period has been declared.

HPA logoOzone High Pollution Advisory

Ground level ozone is formed by a chemical reaction that needs heat from sunlight, nitrogen oxides, and volatile organic compounds (VOCs) to form. The months of April through September make up Maricopa County’s “ozone season.”

  1. Employees and contractors of government entities are prohibited from operating leaf blowers. Residents are encouraged to avoid leaf blowing during HPAs.
  2. Open burning activity is restricted in Maricopa County. This includes individuals and businesses which have burn permits for open burning. Wood burning in residential fireplaces, chimineas, outdoor fire pits, and similar outdoor fires is prohibited.

HPA logoPM10 High Pollution Advisory

PM10 is coarse particulate matter less than 10 micrometers in diameter that are generally emitted from sources such as vehicles traveling on unpaved roads, materials handling, and crushing and grinding operations, as well as windblown dust.

  1. Employees and contractors of government entities are prohibited from operating leaf blowers. Residents are encouraged to avoid leaf blowing during HPAs.
  2. Wood burning in residential fireplaces, chimineas, outdoor fire pits, and similar outdoor fires is prohibited.
  3. Off-Highway Vehicles (OHVs) being used in Area A is prohibited.

HPA logoPM2.5 High Pollution Advisory

PM2.5 is fine particulate matter less than 2.5 micrometers in diameter that result from fuel combustion from motor vehicles, power generation, and industrial facilities, as well as from residential fireplaces and wood stoves.

  1. Employees and contractors of government entities are prohibited from operating leaf blowers. Residents are encouraged to avoid leaf blowing during HPAs.
  2. Wood burning in residential fireplaces, chimineas, outdoor fire pits, and similar outdoor fires is prohibited.
  3. Off-Highway Vehicles (OHVs) being used in Area A is prohibited.

No Burn Day

The Maricopa County Air Quality Department (MCAQD) declares No Burn Days according to values set by the P-26 Residential Wood Burning Restriction Ordinance. The Arizona Department of Environmental Quality (ADEQ) issues High Pollution Watches/Advisories based on the EPA federal health standard (>100 AQI).

ADEQ Air Quality 
Forecast AQI Value
No Burn Day issued 
by MCAQD?
High Pollution Advisory 
issued by ADEQ?
PM10 or PM2.5 : 101 AQI+
YesYes
PM10 : 83 – 100 AQI
YesNo
PM2.5 : 89 – 100 AQI
YesNo

Page reviewed 29 December 2023